- Email: [email protected]
Impact of physical symptoms on perceived health in the community
Journal of Psychosomatic Research 64 (2008) 265 – 274
Impact of physical symptoms on perceived health in the community☆ Daniëlle A.W.M. van der Windt a,b,⁎, Kate M. Dunn a , Marinda N. Spies-Dorgelo b , Christian D. Mallen a , Antoinette H. Blankenstein b , Wim A.B. Stalman b a
Primary Care Musculoskeletal Research Centre, Primary Care Sciences, Keele University, Keele, Staffordshire, United Kingdom b EMGO Institute and Department of General Practice, VU University Medical Centre, Amsterdam, The Netherlands Received 6 March 2007; received in revised form 4 October 2007; accepted 9 October 2007
Abstract Objective: Physical symptoms, such as musculoskeletal pain, dizziness, or headache, are common. People with more symptoms are reported to use more healthcare and have higher sickness absenteeism. We studied the impact of the number of symptoms on perceived health in a community sample. Methods: Between June 2005 and March 2006, a random sample of 4741 adults was selected from the records of five general practices in The Netherlands. They were sent a questionnaire regarding the frequency and impact of physical symptoms, and other factors that may influence health (potential confounders or modifiers), including lifestyle factors, childhood illness experiences, and psychological factors. We studied the association between increasing number of physical symptoms and perceived health using the SF-36 as the outcome measure. Results: Response rate was 53.5% (n=2447). Fatigue was the most commonly reported
symptom with a prevalence of 57%, followed by headache (40%) and back pain (39%). More than half of responders reported three symptoms or more. Responders with multiple symptoms were more often female, had lower educational level, less often paid work, higher body mass index, more negative childhood health experiences, and higher scores for anxiety and depression. Multiple symptoms were strongly associated with perceived health, especially among responders with negative illness perceptions, more anxiety, or those reporting family members with a chronic illness during childhood. Conclusion: Physical symptoms are common and often seem to be mild. However, increasing number of symptoms is strongly associated with poorer physical, emotional, and social functioning. Different somatization processes may explain our findings. © 2008 Elsevier Inc. All rights reserved.
Keywords: Physical symptoms; Community survey; Health behavior; Anxiety; Depression; Health
Introduction Physical symptoms, such as fatigue, musculoskeletal pain, dizziness, or abdominal pain, are common and are among the top 10 reasons for consultation in primary care [1–7]. In many consulters there is no identifiable pathology ☆ Funding: The study was made possible by a grant from the Netherlands Organisation for Health Research and Development (ZonMw no. 4200.0007). ⁎ Corresponding author. Primary Care Musculoskeletal Research Centre, Primary Care Sciences, Keele University, Keele, ST5 5BG Staffordshire, United Kingdom. Tel.: +44 1782 583 927; fax: +44 1782 583 911. E-mail address: [email protected] (D.A.W.M. van der Windt). URL: http://www.keele.ac.uk/research/pchs (D.A.W.M. van der Windt).
0022-3999/08/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.jpsychores.2007.10.003
to explain the symptoms. It has been estimated that unexplained physical symptoms are responsible for 30% to 50% of all physician visits [8,9]. Research among primary care consulters has shown that when the number of physical symptoms increases, the number of psychological distress symptoms and functional impairment increases [10,11]. People with more symptoms are reported to use more healthcare and have higher sickness absenteeism [12–14]. Many studies on unexplained physical symptoms have been performed among patients with diagnosed chronic functional syndromes such as fibromyalgia, irritable bowel syndrome, or chronic fatigue syndrome [15–17]. However, these syndromes represent the far end of the spectrum of unexplained symptoms. The results from these populations may not be generalisable to the large number of people
266
D.A.W.M. van der Windt et al. / Journal of Psychosomatic Research 64 (2008) 265–274
who report multiple physical symptoms but do not necessarily meet the criteria for a chronic functional syndrome. We therefore set out to study such symptoms in a community sample of adults in order to estimate their impact on perceived health, and on physical, emotional, and social functioning. Several explanations have been offered for the occurrence and impact of unexplained physical symptoms. Although physiological processes, especially neurohormonal dysfunction, may be involved in the development of chronic fatigue and pain syndromes [18–20], there is evidence to suggest that increased attention to bodily sensations, poor illness perceptions, anxiety, and depressive disorders may play important roles in illness behavior and presence of unexplained physical symptoms [21–24]. Furthermore, adverse childhood experiences and parental modelling of illness behavior have been shown to be associated with increased adult vulnerability to somatization and the development of chronic pain or other functional syndromes [25–27]. We therefore investigated in a community sample whether the association between increasing number of physical symptoms and poor perceived health was explained or modified by other indicators of health, including body mass index, sleeping problems, anxiety and depression, illness perceptions, and childhood health experiences.
Methods
Data collection All eligible adults received a letter from their GP along with an information leaflet and questionnaire, inviting them to participate by returning the questionnaire and signed consent form. A reminder was sent after 2 weeks, along with a nonresponse card on which reasons for not wanting to participate could be indicated. After 4 weeks, a second, final reminder was sent to nonresponders who had not returned a nonresponse card, together with a second copy of the questionnaire. The questionnaire included questions regarding common physical symptoms (independent variable), perceived health (dependent variable), and other potential indicators of health (socio-demographic variables, lifestyle factors, childhood health experiences, anxiety, depression, and illness perceptions). Common physical symptoms Responders were asked to indicate the presence (lasting at least 24 h in the past month) [29–31] of the following symptoms: fatigue, headache, dizziness, abdominal pain, and musculoskeletal pain (seven locations). If present, for each symptom additional questions concerned the duration of symptoms (b1 month, 1–3 months, 3–6 months, N6 months); frequency and impact on daily activities (both scored as sometimes/about once a month, often/ about 5 days per month, or very often/more than half of all days); and whether or not the GP had been consulted. The internal consistency of the checklist was adequate (Cronbach alpha 0.75).
Design This study is part of a population-based cohort study on the course and impact of physical symptoms. For this study, a general questionnaire about health was distributed among a random sample of adults registered with five general practices in The Netherlands. Approval for the study was obtained from the Medical Ethics Committee of the VU University Medical Centre in Amsterdam.
Perceived health The Dutch version of the Short-Form 36 (SF-36) was used to measure perceived health [32,33]. The eight scales measured by the SF-36 are physical functioning, role limitations in physical functioning, role limitations in emotional functioning, social functioning, bodily pain, mental health, vitality, and general health perceptions. Scale scores range from 0 to 100 with higher scores representing better perceived health.
Study population As nearly all residents in the Netherlands are registered with a general practitioner (GP) [28], practice registers provide a convenient sampling frame for a population-based cohort. The five participating practices varied with respect to size (2730 to 6537 registered patients), number of GPs (2 to 5), and location (rural and urban, more and less deprived areas). We selected a random sample of approximately 20% of adults (≥18 years) per practice, sampling only one adult from each household to avoid contamination [13]. Prior to the mailing, samples were checked by the GPs. They used their knowledge of the patient to exclude those with a terminal disease, severe psychiatric illness, and those unable to complete written questionnaires due to language or cognitive problems.
Other health indicators Socio-demographic variables included age, sex, educational level, marital status, and work status (paid work or not). Lifestyle factors included alcohol consumption (number of units per week), previous or current smoking, and physical activity. Those who reported at least 30 min of moderate-intensity physical activity on at least 5 days of the week were coded as meeting the Norm for Healthy Activity [34,35]. Additionally, responders who performed heavy physical exercise or sports at least three times a week were coded as meeting the American College of Sports Medicine position stand [36]. Additionally, we asked participants for information on height and body weight, from which body mass index (BMI) was calculated. Obesity was defined as BMI of 30 or higher.
D.A.W.M. van der Windt et al. / Journal of Psychosomatic Research 64 (2008) 265–274
Health experiences during childhood (4 to 16 years of age) were assessed using questions regarding hospitalization during childhood (at least one episode lasting more than 3 days); whether the responder had been ill more often than other children; and whether the responders remembered having one or more chronically ill direct family members [27]. Anxiety and depressive symptoms were measured with the Hospital Anxiety and Depression Scale (HADS) [37], a well-validated measure that is particularly useful as a screening tool for anxiety and depression in the general population [38]. Total scores for anxiety and depression (seven items each) range between 0 and 21 points, with higher scores indicating more severe symptoms. Both continuous and categorical outcomes were used. For the categorical analysis, scores of 0 to 7 points indicated no anxiety or depression, scores of 8 to 10 points possible, and 11 or higher probable anxiety or depression [39]. Finally, one item of the Illness Perception Questionnaire [40] was used to assess whether responders felt they were able to influence their own health (5-point scale; fully agree to fully disagree). Statistical analysis Response rates were calculated and adjusted for incorrect addresses and persons who had died or moved out of the area. The prevalence of each physical symptom was computed. We subsequently computed a summated score, indicating the number of symptoms experienced by the responders over the past month. For further analyses this score was divided into four categories: no symptoms, 1 or 2 symptoms, 3 to 5 symptoms, or more than 5 symptoms [13]. For each of these four categories mean scores on the SF-36 were calculated. The association between increasing number of symptoms and health indicators was described and tested for significance using ANOVA for continuous variables and χ2 tests for categorical variables. In subsequent analyses of perceived health we included two dependent variables: the physical functioning subscale and the first item of the general health perceptions subscale (SF-1) of the SF-36. In the SF-1, the responder scores his/her general health on a scale ranging between 1 (excellent) and 5 (poor). We studied the association between increasing number of symptoms and perceived health using linear regression, adjusting associations for potential confounding by age and sex. Confounding by other health indicators was studied using a manual forward selection procedure. Sequentially, the confounder with the strongest influence on the association between symptoms and health was added to the model. Health indicators that changed the multivariable regression coefficient of the number of symptoms by more than 10% were retained in the model. Finally, in order to study to what extent health indicators modified the association between the number of symptoms and perceived health, we added interaction terms to the
267
model. The following variables were considered as potential modifiers: age; sex; sleeping problems; obesity; childhood experiences; anxiety and depressive symptoms; and illness perceptions. In case of a significant association of the interaction term with perceived health (Pb.10), stratified analyses were carried out. All analyses were performed using SPSS for Windows version 12.1 (SPSS Inc., Chicago, IL, USA).
Results Study population A total of 4741 questionnaires were distributed, of which 171 were returned because people had died, or addresses were incorrect. A total of 2447 responders completed the questionnaire, resulting in an adjusted response rate of 53.5%. Of the responders, 62.5% returned the questionnaire after the first mailing, 18.6% after the reminder, and 18.9% after the last mailing. Responders more often were female (58.4% compared to 53.8% in the total sample) and older (mean age 49.9 compared to 46.8 years). The proportion of responders with higher depression scores (N7 points) significantly increased with each mailing; from 22.1% in the first mailing to 27.9% of responders in the final mailing. The same was found for anxiety, with the proportion of higher scores increasing from 14.9% to 19.3%. However, late responders were similar to early responders in the prevalence of symptoms and perceived health. Of all nonresponders, 20% (n=579) provided reasons for not participating in the survey. The majority (52%) indicated that they had no interest or time to participate; 29% had no health problems; 6% indicated that they were too ill; 4% were too old or found the questionnaire too difficult; and 9% refused participation for other reasons. For the 2447 responders, Table 1 presents sociodemographic characteristics, self-reported chronic disease, lifestyle factors, and psychological factors. The results show that 50% of responders were overweight or obese, 25.8% were current smokers, and only a minority reported frequent physical activity. Increased scores for anxiety or depression (N7 points) were found among 23.5% and 16.1% of responders, respectively. Physical symptoms Eighty-six percent of all responders reported one or more physical symptoms. The most commonly reported symptom was fatigue with a prevalence of 57%. Headache or low back pain was reported by approximately 40% of all responders (Table 2). Table 2 shows that there was some variation between different symptoms in frequency, duration, or impact on daily activities. Musculoskeletal symptoms more often lasted for more than 6 months, occurred on more days, and more
268
D.A.W.M. van der Windt et al. / Journal of Psychosomatic Research 64 (2008) 265–274
Table 1 Characteristics of the community sample, Netherlands, 2005–2006 (n=2447) Demographic variables Age (years), mean (S.D.) Sex, n (% female) Educational level, n (%) Primary Secondary College/university Paid work, n (%) Marital status, n (%) Single or divorced Married/living with partner Widow(er) Chronic disease (self-reported), n (%) Asthma or chronic obstructive pulmonary disease Heart disease Diabetes Cancer Rheumatoid arthritis or osteoarthritis Fibromyalgia Lifestyle factors Body mass index, n (%) b18 (underweight) 18 to 25 (normal) 25 to 30 (overweight) N30 (obese) Physically active, n (%) At least three times a week At least 30 min on ≥5 days/week Smoking, n (%) No, never No, in the past Yes Alcohol consumption, n (%) ≤1 U/week 2 to 10 U/week N10 U/week Psychological factors Anxiety (HADS), n (%) No (score 0–7) Possible anxiety (score 8–10) Probable anxiety (score N10) Depressive symptoms (HADS), n (%) No (score 0–7) Possible depression (score 8–10) Probable depression (score N10) Illness perceptions, unable to influence health, n (%) Perceived health (SF-1), n (%) Excellent Very good Good Moderate Poor
49.9 (16.1) 1428 (58.4) 666 (27.3) 898 (36.8) 873 (35.9) 1582 (64.7) 602 (24.7) 1654 (67.6) 189 (7.7) 138 (5.7) 169 (6.9) 128 (5.2) 50 (2.0) 188 (7.7) 31 (1.3)
29 (1.2) 1180 (49.1) 857 (35.7) 335 (14.0) 399 (16.6) 820 (33.5)
combination with other physical symptoms; 90% of those reporting fatigue reported at least one other symptom. Symptoms that appeared to cluster were problems of the back, neck, shoulder, or elbow; problems of the hip, knee, or hand; and abdominal pain, fatigue, headache, or dizziness (data not reported). Physical symptoms and perceived health In the total population, scores on the SF-36 were largely similar to a Dutch reference population [33], although our responders scored lower (1 to 7 points on a scale of 0 to 100) on most of the subscales, indicating slightly poorer perceived health. Table 3 shows that increasing number of physical symptoms was strongly and significantly associated with lower scores on each subscale of the SF-36. The largest impact of symptoms was found for bodily pain and role limitations in physical functioning. The mean (S.D.) scores among responders not reporting any symptom were 96 (10) for bodily pain and 97 (14) for role limitations in physical functioning, whereas mean scores were 54 (21) and 47 (42), respectively, for responders reporting six symptoms or more. The mean (S.D.) scores for overall perceived health (single item, SF-1) varied from 2.4 (0.8) for responders without symptoms to 3.6 (0.7) for those reporting six symptoms or more (higher scores indicating poorer health). Physical symptoms and other health indicators
932 (38.2) 875 (36.0) 629 (25.8) 1094 (44.9) 974 (40.0) 367 (15.1)
1852 (76.5) 336 (13.9) 232 (9.6) 2032 (83.9) 228 (9.4) 161 (6.7) 194 (7.9) 124 (5.1) 375 (15.4) 1346 (55.2) 517 (21.2) 76 (3.1)
often influenced daily activities, compared with other physical symptoms. The proportion of responders who indicated that they had consulted their GP varied between 15.6% for fatigue and 32.0% for ankle or foot problems. The majority of responders reported more than one symptom, with fatigue most commonly occurring in
Nearly all health indicators were significantly associated with increasing number of symptoms, with the exception of physical activity and smoking. Table 3 shows that responders with multiple symptoms were more often female, had lower educational level, no paid work, a higher body mass index, more negative childhood health experiences, more difficulties sleeping, higher scores for anxiety and depression, and more often reported that they could not influence their health. Table 4 presents the mean differences for perceived health (SF-1) for increasing number of symptoms, adjusted for confounding. Only anxiety and depression influenced (weakened) the association between increasing number of symptoms and perceived health. After adjustment for confounding, responders with multiple (≥6) symptoms on average scored nearly 1 point worse on perceived health (scale 1 to 5) compared to those without symptoms. Two health indicators significantly modified the association between increasing symptoms and perceived health. Table 4 shows that among responders who felt that they were unable to influence their own health, and among responders who remembered at least one family member with chronic disease during their childhood, the association between multiple symptoms and perceived health was especially strong. Similar results were found for physical functioning, with an increasing number of symptoms showing a significant
D.A.W.M. van der Windt et al. / Journal of Psychosomatic Research 64 (2008) 265–274
269
Table 2 Frequency, duration, and impact of physical symptoms on daily activities, and physician consultation in a community sample (n=2447) Duration N6 months (%)
Frequency (very often) a (%)
Impact on daily activities (very often) a (%)
Consulted GP (%)
Symptom, n (% of total population) Fatigue, n=1395 (57.0%) Headache, n=991 (40.4%) Dizziness, n=469 (19.1%) Abdominal symptoms, n=574 (23.4%)
62.9 60.8 56.8 58.6
38.3 16.0 21.2 29.5
24.4 10.9 20.7 18.1
15.6 14.7 28.8 29.2
Musculoskeletal pain Hand/wrist, n=563 (23.0%) Elbow/arm, n=408 (16.6%) Shoulder, n=710 (29.0%) Neck, n=754 (30.8%) Back, n=960 (39.2%) Hip/knee, n=693 (28.3%) Ankle/foot, n=428 (17.4%)
68.5 68.0 67.8 71.7 74.2 77.3 70.8
52.2 56.3 50.9 46.6 45.0 54.7 61.0
37.3 37.3 33.1 31.5 32.4 39.8 42.3
18.1 21.6 20.6 19.6 22.4 25.1 32.0
a
On more than half of all days.
impact on functioning. Adjusted for confounding the mean score on physical functioning was 20 points lower in patients reporting ≥6 symptoms, compared to those without symptoms (Table 5). Illness perceptions modified the association also for this outcome measure. Additionally, the association between symptoms and physical functioning was modified by anxiety, with stronger associations found for responders with more anxiety (HADS ≥8). Discussion The results of this community survey show that many people regularly experience physical symptoms. In most responders, symptoms were mild in terms of impact on daily activities, and only a minority had consulted the GP for their symptoms. However, an increasing number of symptoms was strongly associated with decreasing levels of perceived health. The association between physical symptoms and health was particularly strong in responders with negative illness perceptions, in those who reported close family members with a chronic illness during their childhood, or in those reporting more symptoms of anxiety. Strengths and weaknesses Our study addressed a range of physical symptoms in a large population-based sample, whereas most studies have focussed on specific types of symptoms. The prevalence of fatigue, headache, dizziness, abdominal pain, or musculoskeletal pain in our study population was largely the same as reported in other surveys, if some variation in the definition of a symptom or episode is taken into account. For example, the prevalence of shoulder pain in our study was 30% compared to 29% and 31% in other studies [29,41]; 39% for back pain compared to 39% and 44% [30,41]; 23% for abdominal pain compared to 23%
and 18% [42]; and 19% for dizziness compared to 16–35% [7]. The response to our survey was similar compared with other symptom surveys in the general population [1,5,16,41], but the risk of selective nonresponse needs to be considered. In our study, responders were more often female, and a few years older than nonresponders. Additionally, nonresponders who provided a reason for not participating often indicated that they had no health problems. Analyses of response to subsequent mailings showed that there might be some selective nonresponse of persons with more anxiety or depression. However, the number of symptoms, and scores on perceived health were similar in early and late responders. Any selective nonresponse is unlikely to have affected the reported associations among health indicators, multiple symptoms, and perceived health, which are the main focus of this paper. We want to emphasize that we used cross-sectional data and cannot draw any conclusions regarding the direction or causality of the reported associations between health indicators, symptoms, and perceived health. For example, depressive symptoms may be a consequence of poor health and physical symptoms, but it is equally likely that depressive mood leads to more symptoms and poorer health perceptions. Longitudinal research is needed to look more closely at the temporal associations between multiple physical symptoms and health, and at the influence of other factors such as lifestyle, psychological factors, or childhood experiences on the development of such associations. Multiple symptoms and perceived health When investigating multiple symptoms, most researchers have studied consulters in primary or secondary care or have focused on patients diagnosed with chronic functional syndromes. Kroenke et al. [10] showed that among primary
270
D.A.W.M. van der Windt et al. / Journal of Psychosomatic Research 64 (2008) 265–274
Table 3 Association between characteristics of responders and number of physical symptoms in a community sample
Demographic variables Sex (% female) Age (years), mean (S.D.) Educational level (%) Primary Secondary College/university Paid work (%) Lifestyle factors Body mass index (%) b18 (underweight) 18 to 25 (normal weight) 25 to 30 (overweight) N30 (obese) Physically active, n (%) At least 3 times/week At least 30 min, ≥5 days/week Smoking (% yes) Alcohol consumption (%) b1 U/week 2–10 U/week N10 U/week Childhood experiences More often ill than other children (%) Admitted to hospital as a child (%) Family members with chronic illness (%) Psychological factors Anxiety (HADS, %) No (score 0–7) Possible anxiety (score 8–10) Probable anxiety (score N10) Depressive symptoms (HADS, %) No (score 0–7) Possible depression (score 8–10) Probable depression (N10) Sleeping problems (N50% of nights, %) Illness perceptions: not able to influence health (%) Perceived health (SF-36) Physical functioning (0–100) Role functioning, physical (0–100) Role functioning, emotional (0–100) Social functioning (0–100) Bodily pain (0–100) Mental health (0–100) Vitality (0–100) General health (0–100)
No symptoms (n=346)
1 or 2 (n=763)
3, 4, or 5 (n=889)
≥6 (n=449)
P value ⁎
42.5 52.6 (17.5)
52.0 50.0 (16.1)
63.0 48.9 (15.9)
72.2 49.8 (15.2)
b.001 .004
27.2 34.5 38.3 73.7
25.8 35.5 38.8 67.2
24.9 37.5 37.5 69.9
34.6 39.7 25.7 60.0
b.001
1.2 49.4 40.9 8.5
0.7 53.9 33.5 11.9
1.6 47.5 35.8 15.1
1.4 44.1 35.2 19.3
20.8 33.7 23.8
16.4 33.4 24.1
16.4 33.2 25.9
14.3 37.4 30.1
33.6 47.2 19.1
37.5 47.3 15.2
47.4 36.8 15.7
61.1 28.3 10.5
5.2 21.5 17.4
8.0 27.7 26.7
12.2 28.6 29.1
19.2 34.6 38.4
95.7 3.5 0.9
87.0 8.5 4.5
72.2 18.0 9.8
52.5 23.0 24.5
95.0 3.5 1.5 4.3 5.6
90.8 5.8 3.3 6.3 6.7
82.0 10.4 7.4 13.6 7.7
67.4 18.2 14.4 30.5 12.7
b.001 .001
93 97 95 93 96 83 77 77
86 82 89 86 80 79 68 71
80 (23) 69 (38) 78 (37) 77 (25) 69 (20) 71 (18) 58 (19) 62 (18)
67 47 61 65 54 63 47 50
b.001 b.001 b.001 b.001 b.001 b.001 b.001 b.001
.002
b.001
.115 .414 .097 b.001
b.001 .001 b.001 b.001
b.001
(14) (14) (18) (14) (10) (12) (14) (13)
(20) (32) (26) (19) (19) (14) (17) (16)
(26) (42) (44) (29) (21) (20) (19) (20)
⁎ ANOVA for continuous measures, or χ2 test for categorical measures.
care consulters the number of physical symptoms was highly predictive of functional impairment and psychiatric disorders. Studies among patients with functional bowel disorders, posttraumatic distress disorder, chronic widespread pain, and chronic fatigue syndrome have also shown that multiple physical symptoms are associated with psychological morbidity, poor illness perceptions, and childhood adversities [23,42–44]. We were particularly
interested to see whether the same correlations were of importance in a community-based sample, largely consisting of people reporting mild physical symptoms. Our results do confirm these findings: responders with multiple symptoms reported more negative childhood health experiences and more psychological distress. Additionally, with increasing number of symptoms we found more sleeping problems, higher BMI, and poorer scores for every dimension of health.
D.A.W.M. van der Windt et al. / Journal of Psychosomatic Research 64 (2008) 265–274
271
Table 4 Association between number of physical symptoms and perceived health (SF-1, score range 1–5, higher score indicating poorer health) No. of symptoms All responders (N=2438) 1 or 2 symptoms 3 to 5 symptoms ≥6 symptoms Health perceptions Able to influence health (n=1744) 1 or 2 symptoms 3 to 5 symptoms ≥6 symptoms Unable to influence health (n=193) 1 or 2 symptoms 3 to 5 symptoms ≥6 symptoms Family member with illness None (n=1739) 1 or 2 symptoms 3 to 5 symptoms ≥6 symptoms ≥1 family member (n=689) 1 or 2 symptoms 3 to 5 symptoms ≥6 symptoms
Mean difference (SF-1 ⁎ adjusted for age, sex)
95% CI
Mean difference (SF-1 ⁎ adjusted for age, sex, anxiety, depression)
95% CI
0.43 0.75 1.23
0.33–0.52 0.66–0.84 1.13–1.34
0.34 0.56 0.91
0.25–0.43 0.47–0.65 0.80–1.01
0.37 0.66 1.11
0.27–0.47 0.56–0.76 0.98–1.23
0.29 0.49 0.82
0.19–0.39 0.39–0.60 0.69–0.94
0.95 1.30 1.77
0.55–1.35 0.91–1.68 1.37–2.16
0.86 1.08 1.44
0.47–1.24 0.70–1.47 1.03–1.86
0.35 0.72 1.18
0.24–0.45 0.61–0.82 1.06–1.31
0.28 0.53 0.88
0.18–0.38 0.42–0.63 0.75–1.00
0.70 0.89 1.41
0.48–0.91 0.68–1.10 1.19–1.63
0.56 0.70 1.03
0.36–0.77 0.49–0.90 0.81–1.26
SF-1=first item Short-Form 36; CI=confidence interval. ⁎ Linear regression analysis; “no symptoms” is reference category.
Childhood health experiences We found that the association between multiple symptoms and perceived health was modified by childhood experiences with disease, but only when using overall health as the outcome measure. We asked our responders retrospectively about childhood health experiences and had no access to data that can be used to verify these reports. Recall bias is likely to be a larger problem in those with multiple symptoms. McBeth et al. [45] found that associations between chronic widespread pain and adverse childhood events were largely explained by differential recall. Mallen et al. [27] found that recalled childhood experiences of pain or illness were associated with current pain status in young adulthood. Young adults with pain remembered themselves as being comparatively ill as a child and aware of family members with pain. Families may have illnesses that are inherited, which may explain trends within family groups. However, the results could equally be related to learned behavior and modelling, which is particularly potent in childhood. In a prospective birth cohort, Hotopf et al. [25] showed a strong relationship between poor reported health of parents in 15-year-old children and symptoms later in adulthood. Unexplained symptoms during adulthood were also associated with abdominal pain in childhood but not with specific childhood disease. These results seemed to indicate that unexplained symptoms can be related to prior experience of family
illness and previous unexplained symptoms in the individual, reflecting a learned process whereby illness experience leads to more symptom awareness [25]. Anxiety The findings of other community and primary care studies support a close and linear relation between the number of bodily symptoms and measures of emotional distress. [10,46,47] In a prospective study among secondary care consulters, Jackson et al. [48] recently reported a significant association between the number of symptoms and poorer perceived health (SF-36), and that this association was independent of anxiety and depression. Our findings additionally show that anxiety modifies the relation between symptoms and health, with a stronger impact on physical functioning found in responders with more anxiety. People who are under stress may be quicker to ascribe physical symptoms to disease, rather than to normal physiology. Anxiety has also been reported to decrease pain threshold or pain tolerance [8,24,49]. Illness perceptions We found a stronger association between multiple symptoms and both physical functioning and perceived health among responders who felt they were unable to influence their own health. Poor perceptions about health
272
D.A.W.M. van der Windt et al. / Journal of Psychosomatic Research 64 (2008) 265–274
Table 5 Association between number of physical symptoms and physical functioning (SF-36, score range 0–100, higher scores indicating better functioning)
No. of symptoms All responders (n=2423) 1 or 2 symptoms 3 to 5 symptoms ≥6 symptoms Health perceptions Able to influence health (n=1744) 1 or 2 symptoms 3 to 5 symptoms ≥6 symptoms Unable to influence health (n=188) 1 or 2 symptoms 3 to 5 symptoms ≥6 symptoms Anxiety No anxiety (n=1837) 1 or 2 symptoms 3 to 5 symptoms ≥6 symptoms Possible/probable anxiety (n=559) 1 or 2 symptoms 3 to 5 symptoms ≥6 symptoms
Mean difference (physical functioning ⁎ adjusted for age, sex)
95% CI
Mean difference (physical functioning ⁎ adjusted for age, sex, anxiety, depression)
95% CI
−8.0 −14.3 −26.4
−10.4 to −5.5 −16.8 to −11.9 −29.1 to −23.6
−6.5 −10.7 −20.1
−9.0 to −4.1 −13.2 to −8.2 −23.1 to −17.2
−6.2 −11.0 −22.6
−8.6 to −3.7 −13.5 to −8.6 −25.5 to −19.6
−4.9 −8.4 −18.0
−7.3 to −2.4 −10.9 to −5.9 −21.1 to −14.9
−21.8 −29.0 −42.0
−35.1 to −8.5 −42.0 to −16,0 −55.4 to −28,7
−18.5 −21.3 −31.3
−31.2 to −5.7 −34.1 to −8.5 −45.0 to −17.5
−7.2 −12.9 −21.6
−9.6 to −4.8 −15.4 to −10.5 −24.7 to −18.5
−5.9 −10.2 −17.8
−8.2 to −3.6 −12.6 to −7.8 −20.8 to −14.8
−16.8 −21.1 −35.3
−29.0 to −4.6 −32.8 to −9.4 −47.1 to −23.5
−17.6 −20.5 −33.0
−29.4 to −5.8 −31.8 to −9.2 −44.4 to −21.6
⁎ Linear regression analysis; “no symptoms” is reference category.
and illness may increase attention to bodily symptoms and strengthen the attribution of such sensations to physical illness. These processes are a normal response to signs of illness in many people, but can reach disabling proportions in some, resulting in (undifferentiated) somatization disorder [24,50,51]. Although we did not measure increased attention to bodily symptoms, processes of somatization may partly explain our findings. Kirmayer and Robbins [52] described different forms of somatization: physical symptoms can be physiological components of anxiety or depression; normal bodily sensations or pathological events can be misinterpreted as signs of serious illness; or subjective physical symptoms may be present without underlying somatic or psychiatric illness. In our population, anxiety and depressive symptoms only partly explained the association between physical symptoms and health, which may indicate that— next to the presence of somatic disease—different forms of somatization can be of importance. Specific somatoform disorders (according to DSM criteria) are not common (prevalence about 1%), but undifferentiated somatization may affect as many as 20% of the population [53,54]. Conclusions The results of our community-based survey show that physical symptoms are common, although their impact on daily activities is limited in most people. However,
increasing number of symptoms—even if mild—are associated with increasing limitations in physical, emotional and social functioning, and poor perceived health. Acknowledgments We gratefully acknowledge Prof. Peter R. Croft, PhD, for his critical review of our manuscript and his useful suggestions. References [1] Pawlikowska T, Chalder T, Hirsch SR, Wallace P, Wright DJ, Wessely SC. Population based study of fatigue and general distress. BMJ 1994; 308:763–6. [2] Gallagher AM, Thomas JM, Hamilton WT, White PD. Incidence of fatigue symptoms and diagnoses presenting in UK primary care from 1990 to 2001. J R Soc Med 2004;97:571–5. [3] Reyes-Gibby CC, Mendoza TR, Wang S, Anderson KO, Cleeland CS. Pain and fatigue in community-dwelling adults. Pain Med 2003;4: 231–7. [4] Papageorgiou AC, Silman AJ, Macfarlane GJ. Chronic widespread pain in the population: a 7-year follow-up study. Ann Rheum Dis 2003; 61:1071–4. [5] Boardman HF, Thomas E, Croft PR, Millson DS. Epidemiology of headache in an English district. Cephalalgia 2003;23:129–37. [6] Hillila MT, Farkkila MA. Prevalence of irritable bowel syndrome according to different diagnostic criteria in a non-selected adult population. Aliment Pharmacol Ther 2004;20:339–45. [7] Sloane PD, Coeytaux RR, Beck RS, Dallara J. Dizziness: state of the science. Ann Intern Med 2001;134:823–32.
D.A.W.M. van der Windt et al. / Journal of Psychosomatic Research 64 (2008) 265–274 [8] Barski AJ, Borus JF. Somatization and medicalization in the era of managed care. JAMA 1995;274:1931–4. [9] Kroenke K, Price RK. Symptoms in the community. Prevalence, classification, and psychiatric comorbidity. Arch Intern Med 1993;153: 2474–80. [10] Kroenke K, Spitzer RL, Williams JB, Linzer M, Hahn SR, deGruy FV, Brody D. Physical symptoms in primary care. Predictors of psychiatric disorders and functional impairment. Am Fam Med 1994;3:774–9. [11] Katon W, Sullivan M, Walker E. Medical symptoms without identified pathology: relationship to psychiatric disorders, childhood and adult trauma, and personality traits. Ann Intern Med 2001;134:917–25. [12] Macfarlane GJ, Hunt IM, McBeth J, Papageorgiou AC, Silman AJ. Chronic widespread pain in the community: influences on health care seeking behaviour. J Rheumatol 1999;26:413–9. [13] Little P, Somerville J, Williamson I, Warner G, Moore M, Wiles R, George S, Smith A, Peveler R. Psychosocial, lifestyle, and health status variables in predicting high attendance among adults. Br J Gen Pract 2001;51:987–94. [14] Reid S, Wessely S, Crayford T, Hotopf M. Frequent attenders with medically unexplained symptoms: service use and costs in secondary care. Br J Psychiatry 2002;180:248–53. [15] White KP, Speechley M, Harth M, Ostbye T. The London Fibromyalgia Study: the prevalence of fibromyalgia syndrome in London, Ontario. J Rheumatol 1999;26:1570–6. [16] Huibers MJ, Kant IJ, Swaen GM, Kasl SV. Prevalence of chronic fatigue syndrome-like caseness in the working population: results from the Maastricht cohort study. Occup Environ Med 2004;61:464–6. [17] Boyce PM, Talley NJ, Burke C, Koloski NA. Epidemiology of the functional gastrointestinal disorders diagnosed according to Rome II criteria: an Australian population-based study. Intern Med J 2006;36: 28–36. [18] Buskila D, Press J. Neuroendocrine mechanisms in fibromyalgiachronic fatigue. Best Pract Res Clin Rheumatol 2001;15:747–58. [19] McBeth J, Chiu YH, Silman AJ, Ray D, Morriss R, Dickens C, Gupta A, Macfarlane GJ. Hypothalamic-pituitary-adrenal stress axis function and the relationship with chronic widespread pain and its antecedents. Arthritis Res Ther 2005;7:R992–R1000. [20] Griep EN, Boersma JW, Lentjes EG, Prins AP, van der Korst JK, de Kloet ER. Function of the hypothalamic-pituitary-adrenal axis in patients with fibromyalgia and low back pain. J Rheumatol 1998;25: 1374–81. [21] Aaron LA, Bichwald D. A review of the evidence for overlap among unexplained clinical conditions. Ann Intern Med 2001;134:868–81. [22] Nimnuan C, Hotopf M, Wessely S. Medically unexplained symptoms: an epidemiological study in seven specialities. J Psychosom Res 2001; 51:361–7. [23] Henningsen P, Zimmermann T, Sattel H. Medically unexplained physical symptoms, anxiety, and depression: a meta-analytic review. Psychosom Med 2003;65:528–33. [24] Kirmayer LJ, Looper KJ. Abnormal illness behaviour: physiological, psychological and social dimensions of coping with distress. Curr Opin Psychiatry 2006;19:54–60. [25] Hotopf M, Mayou R, Wadsworth M, Wessely S. Childhood risk factors for adults with medically unexplained symptoms: results from a national birth cohort study. Am J Psychiatry 1999;156:1796–800. [26] Little P, Somerville J, Williamson I, Warner G, Moore M, Wiles R, George S, Smith A, Peveler R. Family influences in a cross-sectional survey of higher child attendance. Br J Gen Pract 2001;51:977–81, 84. [27] Mallen C, Peat G, Thomas E, Croft P. Is chronic pain in adulthood related to childhood factors? A population-based case-control study of young adults. J Rheumatol 2006;33:2286–90. [28] van der Linden MW, Westert GP, de Bakker DH, Schellevis FG. 2nd National Study of Health and Illness (in Dutch). Utrecht: NIVEL/ RIVM; 2004. [29] Pope DP, Croft PR, Pritchard CM, Silman AJ. Prevalence of shoulder pain in the community: the influence of case definition. Ann Rheum Dis 1997;56:308–12.
273
[30] Papageorgiou AC, Croft PR, Ferry S, Jayson MI, Silman AJ. Estimating the prevalence of low back pain in the general population: evidence from the South Manchester Back Pain Survey. Spine 1995; 20:1889–94. [31] Thomas E, Wilkie R, Peat G, Hill S, Dziedzic K, Croft P. The North Staffordshire Osteoarthritis Project-NorStOP: prospective, 3-year study of the epidemiology and management of clinical osteoarthritis in a general population of older adults. BMC Musculoskelet Disord 2004;5:2. [32] Ware JE, Sherbourne CD. The MOS 36-item short-form health survey (SF-36): I. Conceptual framework and item selection. Med Care 1992; 30:473–83. [33] Aaronson NK, Muller M, Cohen PD, Essink-Bot ML, Fekkes M, Sanderman R, Sprangers MA, Te Velde VA, Verrips E. Translation, validation, and norming of the Dutch language version of the SF-36 Health Survey in community and chronic disease populations. J Clin Epidemiol 1998;51:1055–68. [34] Kemper H, Ooijendijk W, Stiggelbout M. Consensus about the Dutch recommendation for physical activity to promote health (in Dutch). Tijdschr Gezondheidswet 2000;78:180–3. [35] Pate RR, Pratt M, Blair SN, Haskell WL, Macera CA, Bouchard C, Buchner D, Ettinger W, Heath GW, King AC. Physical activity and public health. A recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine. JAMA 1995;273:402–7. [36] American College of Sports Medicine Position Stand. The recommended quantity and quality of exercise for developing and maintaining cardiorespiratory and muscular fitness in healthy adults. Med Sci Sports Exerc 1990;22:265–74. [37] Zigmund AS, Snaith RP. The Hospital Anxiety and Depression Scale. Acta Psychiatr Scand 1983;67:361–70. [38] Spinhoven P, Ormel J, Sloekers PP, Kempen GI, Speckens AE, Van Hemert AM. A validation study of the Hospital Anxiety and Depression Scale (HADS) in different groups of Dutch subjects. Psychol Med 1997;27:363–70. [39] Bjelland I, Dahl AA, Haug TT, Neckelmann D. The validity of the Hospital Anxiety and Depression Scale. An updated literature review. J Psychosom Res 2002;52:69–77. [40] Moss-Morris R, Weinman J, Petrie KJ, Horne R, Cameron LD, Buick D. The Revised Illness Perception Questionnaire (IPQ-R). Psychol Health 2002;7:1–16. [41] Picavet HSJ, Schouten JSAG. Musculoskeletal pain in the Netherlands: prevalences, consequences, and risk groups, the DMC3 study. Pain 2003;102:167–78. [42] Koloski NA, Talley NJ, Boyce PM. Epidemiology and health care seeking in the functional GI disorders: a population-based study. Am J Gastroenterol 2002;97:2290–9. [43] Engel CC, Liu X, McCarthy BD, Miller RF, Ursano R. Relationship of physical symptoms to post traumatic stress disorder among veterans seeking care for gulf war-related health concerns. Psychosom Med 2000;62:739–45. [44] Imbierowitz K, Egle UT. Childhood adversities in patients with fibromyalgia and somatoform pain disorder. Eur J Pain 2003;7: 113–9. [45] McBeth J, Morris S, Benjamin S, Silman AJ, Macfarlane GJ. Associations between adverse events in childhood and chronic widespread pain in adulthood: are they explained by differential recall? J Rheumatol 2001;28:2305–9. [46] Wessely S, Chalder T, Hirsch S, Wallace P, Wright D. Psychological symptoms, somatic symptoms, and psychiatric disorder in chronic fatigue and chronic fatigue syndrome: a prospective study in the primary care setting. Am J Psychiatry 1996;153:1050–9. [47] Simon G, Gater R, Kisely S, Pccinelli M. Somatic symptoms of distress: an international primary care study. Psychosom Med 1996;58: 481–8. [48] Jackson J, Fiddler M, Kapur N, Wells A, Tomenson B, Creed F. Number of bodily symptoms predicts outcome more accurately than
274
D.A.W.M. van der Windt et al. / Journal of Psychosomatic Research 64 (2008) 265–274
health anxiety in patients attending neurology, cardiology, and gastroenterology clinics. J Psychosom Res 2006;60:357–63. [49] Jones A, Zachariae R. Gender, anxiety, and experimental pain sensitivity: an overview. J Am Med Womens Assoc 2002;57:91–4. [50] Brown RJ. Psychological mechanisms of medically unexplained symptoms. Psychol Bull 2004;130:793–812. [51] Escobar JI, Hoyos-Nervi C, Gara M. Medically unexplained symptoms in medical practice. Environ Health Perspect 2002;110(suppl 4): 631–6.
[52] Kirmayer LJ, Robbins JM. Three forms of somatization in primary care: prevalence, co-occurrence, and sociodemographic characteristics. J Nerv Ment Dis 1991;179:647–55. [53] Grabe HJ, Meyer C, Hapke U, Rumpf HJ, Freyberger HJ, Dilling H, John U. Specific somatoform disorders in the general population. Psychosomatic 2003;44:304–11. [54] Karvonen JT, Veijola J, Jokelainen J, Laksy K, Jarvelin MR, Joukamaa M. Somatization disorder in young adult population. Gen Hosp Psych 2004;26:9–12.
Impact of physical symptoms on perceived health in the community☆ Daniëlle A.W.M. van der Windt a,b,⁎, Kate M. Dunn a , Marinda N. Spies-Dorgelo b , Christian D. Mallen a , Antoinette H. Blankenstein b , Wim A.B. Stalman b a
Primary Care Musculoskeletal Research Centre, Primary Care Sciences, Keele University, Keele, Staffordshire, United Kingdom b EMGO Institute and Department of General Practice, VU University Medical Centre, Amsterdam, The Netherlands Received 6 March 2007; received in revised form 4 October 2007; accepted 9 October 2007
Abstract Objective: Physical symptoms, such as musculoskeletal pain, dizziness, or headache, are common. People with more symptoms are reported to use more healthcare and have higher sickness absenteeism. We studied the impact of the number of symptoms on perceived health in a community sample. Methods: Between June 2005 and March 2006, a random sample of 4741 adults was selected from the records of five general practices in The Netherlands. They were sent a questionnaire regarding the frequency and impact of physical symptoms, and other factors that may influence health (potential confounders or modifiers), including lifestyle factors, childhood illness experiences, and psychological factors. We studied the association between increasing number of physical symptoms and perceived health using the SF-36 as the outcome measure. Results: Response rate was 53.5% (n=2447). Fatigue was the most commonly reported
symptom with a prevalence of 57%, followed by headache (40%) and back pain (39%). More than half of responders reported three symptoms or more. Responders with multiple symptoms were more often female, had lower educational level, less often paid work, higher body mass index, more negative childhood health experiences, and higher scores for anxiety and depression. Multiple symptoms were strongly associated with perceived health, especially among responders with negative illness perceptions, more anxiety, or those reporting family members with a chronic illness during childhood. Conclusion: Physical symptoms are common and often seem to be mild. However, increasing number of symptoms is strongly associated with poorer physical, emotional, and social functioning. Different somatization processes may explain our findings. © 2008 Elsevier Inc. All rights reserved.
Keywords: Physical symptoms; Community survey; Health behavior; Anxiety; Depression; Health
Introduction Physical symptoms, such as fatigue, musculoskeletal pain, dizziness, or abdominal pain, are common and are among the top 10 reasons for consultation in primary care [1–7]. In many consulters there is no identifiable pathology ☆ Funding: The study was made possible by a grant from the Netherlands Organisation for Health Research and Development (ZonMw no. 4200.0007). ⁎ Corresponding author. Primary Care Musculoskeletal Research Centre, Primary Care Sciences, Keele University, Keele, ST5 5BG Staffordshire, United Kingdom. Tel.: +44 1782 583 927; fax: +44 1782 583 911. E-mail address: [email protected] (D.A.W.M. van der Windt). URL: http://www.keele.ac.uk/research/pchs (D.A.W.M. van der Windt).
0022-3999/08/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.jpsychores.2007.10.003
to explain the symptoms. It has been estimated that unexplained physical symptoms are responsible for 30% to 50% of all physician visits [8,9]. Research among primary care consulters has shown that when the number of physical symptoms increases, the number of psychological distress symptoms and functional impairment increases [10,11]. People with more symptoms are reported to use more healthcare and have higher sickness absenteeism [12–14]. Many studies on unexplained physical symptoms have been performed among patients with diagnosed chronic functional syndromes such as fibromyalgia, irritable bowel syndrome, or chronic fatigue syndrome [15–17]. However, these syndromes represent the far end of the spectrum of unexplained symptoms. The results from these populations may not be generalisable to the large number of people
266
D.A.W.M. van der Windt et al. / Journal of Psychosomatic Research 64 (2008) 265–274
who report multiple physical symptoms but do not necessarily meet the criteria for a chronic functional syndrome. We therefore set out to study such symptoms in a community sample of adults in order to estimate their impact on perceived health, and on physical, emotional, and social functioning. Several explanations have been offered for the occurrence and impact of unexplained physical symptoms. Although physiological processes, especially neurohormonal dysfunction, may be involved in the development of chronic fatigue and pain syndromes [18–20], there is evidence to suggest that increased attention to bodily sensations, poor illness perceptions, anxiety, and depressive disorders may play important roles in illness behavior and presence of unexplained physical symptoms [21–24]. Furthermore, adverse childhood experiences and parental modelling of illness behavior have been shown to be associated with increased adult vulnerability to somatization and the development of chronic pain or other functional syndromes [25–27]. We therefore investigated in a community sample whether the association between increasing number of physical symptoms and poor perceived health was explained or modified by other indicators of health, including body mass index, sleeping problems, anxiety and depression, illness perceptions, and childhood health experiences.
Methods
Data collection All eligible adults received a letter from their GP along with an information leaflet and questionnaire, inviting them to participate by returning the questionnaire and signed consent form. A reminder was sent after 2 weeks, along with a nonresponse card on which reasons for not wanting to participate could be indicated. After 4 weeks, a second, final reminder was sent to nonresponders who had not returned a nonresponse card, together with a second copy of the questionnaire. The questionnaire included questions regarding common physical symptoms (independent variable), perceived health (dependent variable), and other potential indicators of health (socio-demographic variables, lifestyle factors, childhood health experiences, anxiety, depression, and illness perceptions). Common physical symptoms Responders were asked to indicate the presence (lasting at least 24 h in the past month) [29–31] of the following symptoms: fatigue, headache, dizziness, abdominal pain, and musculoskeletal pain (seven locations). If present, for each symptom additional questions concerned the duration of symptoms (b1 month, 1–3 months, 3–6 months, N6 months); frequency and impact on daily activities (both scored as sometimes/about once a month, often/ about 5 days per month, or very often/more than half of all days); and whether or not the GP had been consulted. The internal consistency of the checklist was adequate (Cronbach alpha 0.75).
Design This study is part of a population-based cohort study on the course and impact of physical symptoms. For this study, a general questionnaire about health was distributed among a random sample of adults registered with five general practices in The Netherlands. Approval for the study was obtained from the Medical Ethics Committee of the VU University Medical Centre in Amsterdam.
Perceived health The Dutch version of the Short-Form 36 (SF-36) was used to measure perceived health [32,33]. The eight scales measured by the SF-36 are physical functioning, role limitations in physical functioning, role limitations in emotional functioning, social functioning, bodily pain, mental health, vitality, and general health perceptions. Scale scores range from 0 to 100 with higher scores representing better perceived health.
Study population As nearly all residents in the Netherlands are registered with a general practitioner (GP) [28], practice registers provide a convenient sampling frame for a population-based cohort. The five participating practices varied with respect to size (2730 to 6537 registered patients), number of GPs (2 to 5), and location (rural and urban, more and less deprived areas). We selected a random sample of approximately 20% of adults (≥18 years) per practice, sampling only one adult from each household to avoid contamination [13]. Prior to the mailing, samples were checked by the GPs. They used their knowledge of the patient to exclude those with a terminal disease, severe psychiatric illness, and those unable to complete written questionnaires due to language or cognitive problems.
Other health indicators Socio-demographic variables included age, sex, educational level, marital status, and work status (paid work or not). Lifestyle factors included alcohol consumption (number of units per week), previous or current smoking, and physical activity. Those who reported at least 30 min of moderate-intensity physical activity on at least 5 days of the week were coded as meeting the Norm for Healthy Activity [34,35]. Additionally, responders who performed heavy physical exercise or sports at least three times a week were coded as meeting the American College of Sports Medicine position stand [36]. Additionally, we asked participants for information on height and body weight, from which body mass index (BMI) was calculated. Obesity was defined as BMI of 30 or higher.
D.A.W.M. van der Windt et al. / Journal of Psychosomatic Research 64 (2008) 265–274
Health experiences during childhood (4 to 16 years of age) were assessed using questions regarding hospitalization during childhood (at least one episode lasting more than 3 days); whether the responder had been ill more often than other children; and whether the responders remembered having one or more chronically ill direct family members [27]. Anxiety and depressive symptoms were measured with the Hospital Anxiety and Depression Scale (HADS) [37], a well-validated measure that is particularly useful as a screening tool for anxiety and depression in the general population [38]. Total scores for anxiety and depression (seven items each) range between 0 and 21 points, with higher scores indicating more severe symptoms. Both continuous and categorical outcomes were used. For the categorical analysis, scores of 0 to 7 points indicated no anxiety or depression, scores of 8 to 10 points possible, and 11 or higher probable anxiety or depression [39]. Finally, one item of the Illness Perception Questionnaire [40] was used to assess whether responders felt they were able to influence their own health (5-point scale; fully agree to fully disagree). Statistical analysis Response rates were calculated and adjusted for incorrect addresses and persons who had died or moved out of the area. The prevalence of each physical symptom was computed. We subsequently computed a summated score, indicating the number of symptoms experienced by the responders over the past month. For further analyses this score was divided into four categories: no symptoms, 1 or 2 symptoms, 3 to 5 symptoms, or more than 5 symptoms [13]. For each of these four categories mean scores on the SF-36 were calculated. The association between increasing number of symptoms and health indicators was described and tested for significance using ANOVA for continuous variables and χ2 tests for categorical variables. In subsequent analyses of perceived health we included two dependent variables: the physical functioning subscale and the first item of the general health perceptions subscale (SF-1) of the SF-36. In the SF-1, the responder scores his/her general health on a scale ranging between 1 (excellent) and 5 (poor). We studied the association between increasing number of symptoms and perceived health using linear regression, adjusting associations for potential confounding by age and sex. Confounding by other health indicators was studied using a manual forward selection procedure. Sequentially, the confounder with the strongest influence on the association between symptoms and health was added to the model. Health indicators that changed the multivariable regression coefficient of the number of symptoms by more than 10% were retained in the model. Finally, in order to study to what extent health indicators modified the association between the number of symptoms and perceived health, we added interaction terms to the
267
model. The following variables were considered as potential modifiers: age; sex; sleeping problems; obesity; childhood experiences; anxiety and depressive symptoms; and illness perceptions. In case of a significant association of the interaction term with perceived health (Pb.10), stratified analyses were carried out. All analyses were performed using SPSS for Windows version 12.1 (SPSS Inc., Chicago, IL, USA).
Results Study population A total of 4741 questionnaires were distributed, of which 171 were returned because people had died, or addresses were incorrect. A total of 2447 responders completed the questionnaire, resulting in an adjusted response rate of 53.5%. Of the responders, 62.5% returned the questionnaire after the first mailing, 18.6% after the reminder, and 18.9% after the last mailing. Responders more often were female (58.4% compared to 53.8% in the total sample) and older (mean age 49.9 compared to 46.8 years). The proportion of responders with higher depression scores (N7 points) significantly increased with each mailing; from 22.1% in the first mailing to 27.9% of responders in the final mailing. The same was found for anxiety, with the proportion of higher scores increasing from 14.9% to 19.3%. However, late responders were similar to early responders in the prevalence of symptoms and perceived health. Of all nonresponders, 20% (n=579) provided reasons for not participating in the survey. The majority (52%) indicated that they had no interest or time to participate; 29% had no health problems; 6% indicated that they were too ill; 4% were too old or found the questionnaire too difficult; and 9% refused participation for other reasons. For the 2447 responders, Table 1 presents sociodemographic characteristics, self-reported chronic disease, lifestyle factors, and psychological factors. The results show that 50% of responders were overweight or obese, 25.8% were current smokers, and only a minority reported frequent physical activity. Increased scores for anxiety or depression (N7 points) were found among 23.5% and 16.1% of responders, respectively. Physical symptoms Eighty-six percent of all responders reported one or more physical symptoms. The most commonly reported symptom was fatigue with a prevalence of 57%. Headache or low back pain was reported by approximately 40% of all responders (Table 2). Table 2 shows that there was some variation between different symptoms in frequency, duration, or impact on daily activities. Musculoskeletal symptoms more often lasted for more than 6 months, occurred on more days, and more
268
D.A.W.M. van der Windt et al. / Journal of Psychosomatic Research 64 (2008) 265–274
Table 1 Characteristics of the community sample, Netherlands, 2005–2006 (n=2447) Demographic variables Age (years), mean (S.D.) Sex, n (% female) Educational level, n (%) Primary Secondary College/university Paid work, n (%) Marital status, n (%) Single or divorced Married/living with partner Widow(er) Chronic disease (self-reported), n (%) Asthma or chronic obstructive pulmonary disease Heart disease Diabetes Cancer Rheumatoid arthritis or osteoarthritis Fibromyalgia Lifestyle factors Body mass index, n (%) b18 (underweight) 18 to 25 (normal) 25 to 30 (overweight) N30 (obese) Physically active, n (%) At least three times a week At least 30 min on ≥5 days/week Smoking, n (%) No, never No, in the past Yes Alcohol consumption, n (%) ≤1 U/week 2 to 10 U/week N10 U/week Psychological factors Anxiety (HADS), n (%) No (score 0–7) Possible anxiety (score 8–10) Probable anxiety (score N10) Depressive symptoms (HADS), n (%) No (score 0–7) Possible depression (score 8–10) Probable depression (score N10) Illness perceptions, unable to influence health, n (%) Perceived health (SF-1), n (%) Excellent Very good Good Moderate Poor
49.9 (16.1) 1428 (58.4) 666 (27.3) 898 (36.8) 873 (35.9) 1582 (64.7) 602 (24.7) 1654 (67.6) 189 (7.7) 138 (5.7) 169 (6.9) 128 (5.2) 50 (2.0) 188 (7.7) 31 (1.3)
29 (1.2) 1180 (49.1) 857 (35.7) 335 (14.0) 399 (16.6) 820 (33.5)
combination with other physical symptoms; 90% of those reporting fatigue reported at least one other symptom. Symptoms that appeared to cluster were problems of the back, neck, shoulder, or elbow; problems of the hip, knee, or hand; and abdominal pain, fatigue, headache, or dizziness (data not reported). Physical symptoms and perceived health In the total population, scores on the SF-36 were largely similar to a Dutch reference population [33], although our responders scored lower (1 to 7 points on a scale of 0 to 100) on most of the subscales, indicating slightly poorer perceived health. Table 3 shows that increasing number of physical symptoms was strongly and significantly associated with lower scores on each subscale of the SF-36. The largest impact of symptoms was found for bodily pain and role limitations in physical functioning. The mean (S.D.) scores among responders not reporting any symptom were 96 (10) for bodily pain and 97 (14) for role limitations in physical functioning, whereas mean scores were 54 (21) and 47 (42), respectively, for responders reporting six symptoms or more. The mean (S.D.) scores for overall perceived health (single item, SF-1) varied from 2.4 (0.8) for responders without symptoms to 3.6 (0.7) for those reporting six symptoms or more (higher scores indicating poorer health). Physical symptoms and other health indicators
932 (38.2) 875 (36.0) 629 (25.8) 1094 (44.9) 974 (40.0) 367 (15.1)
1852 (76.5) 336 (13.9) 232 (9.6) 2032 (83.9) 228 (9.4) 161 (6.7) 194 (7.9) 124 (5.1) 375 (15.4) 1346 (55.2) 517 (21.2) 76 (3.1)
often influenced daily activities, compared with other physical symptoms. The proportion of responders who indicated that they had consulted their GP varied between 15.6% for fatigue and 32.0% for ankle or foot problems. The majority of responders reported more than one symptom, with fatigue most commonly occurring in
Nearly all health indicators were significantly associated with increasing number of symptoms, with the exception of physical activity and smoking. Table 3 shows that responders with multiple symptoms were more often female, had lower educational level, no paid work, a higher body mass index, more negative childhood health experiences, more difficulties sleeping, higher scores for anxiety and depression, and more often reported that they could not influence their health. Table 4 presents the mean differences for perceived health (SF-1) for increasing number of symptoms, adjusted for confounding. Only anxiety and depression influenced (weakened) the association between increasing number of symptoms and perceived health. After adjustment for confounding, responders with multiple (≥6) symptoms on average scored nearly 1 point worse on perceived health (scale 1 to 5) compared to those without symptoms. Two health indicators significantly modified the association between increasing symptoms and perceived health. Table 4 shows that among responders who felt that they were unable to influence their own health, and among responders who remembered at least one family member with chronic disease during their childhood, the association between multiple symptoms and perceived health was especially strong. Similar results were found for physical functioning, with an increasing number of symptoms showing a significant
D.A.W.M. van der Windt et al. / Journal of Psychosomatic Research 64 (2008) 265–274
269
Table 2 Frequency, duration, and impact of physical symptoms on daily activities, and physician consultation in a community sample (n=2447) Duration N6 months (%)
Frequency (very often) a (%)
Impact on daily activities (very often) a (%)
Consulted GP (%)
Symptom, n (% of total population) Fatigue, n=1395 (57.0%) Headache, n=991 (40.4%) Dizziness, n=469 (19.1%) Abdominal symptoms, n=574 (23.4%)
62.9 60.8 56.8 58.6
38.3 16.0 21.2 29.5
24.4 10.9 20.7 18.1
15.6 14.7 28.8 29.2
Musculoskeletal pain Hand/wrist, n=563 (23.0%) Elbow/arm, n=408 (16.6%) Shoulder, n=710 (29.0%) Neck, n=754 (30.8%) Back, n=960 (39.2%) Hip/knee, n=693 (28.3%) Ankle/foot, n=428 (17.4%)
68.5 68.0 67.8 71.7 74.2 77.3 70.8
52.2 56.3 50.9 46.6 45.0 54.7 61.0
37.3 37.3 33.1 31.5 32.4 39.8 42.3
18.1 21.6 20.6 19.6 22.4 25.1 32.0
a
On more than half of all days.
impact on functioning. Adjusted for confounding the mean score on physical functioning was 20 points lower in patients reporting ≥6 symptoms, compared to those without symptoms (Table 5). Illness perceptions modified the association also for this outcome measure. Additionally, the association between symptoms and physical functioning was modified by anxiety, with stronger associations found for responders with more anxiety (HADS ≥8). Discussion The results of this community survey show that many people regularly experience physical symptoms. In most responders, symptoms were mild in terms of impact on daily activities, and only a minority had consulted the GP for their symptoms. However, an increasing number of symptoms was strongly associated with decreasing levels of perceived health. The association between physical symptoms and health was particularly strong in responders with negative illness perceptions, in those who reported close family members with a chronic illness during their childhood, or in those reporting more symptoms of anxiety. Strengths and weaknesses Our study addressed a range of physical symptoms in a large population-based sample, whereas most studies have focussed on specific types of symptoms. The prevalence of fatigue, headache, dizziness, abdominal pain, or musculoskeletal pain in our study population was largely the same as reported in other surveys, if some variation in the definition of a symptom or episode is taken into account. For example, the prevalence of shoulder pain in our study was 30% compared to 29% and 31% in other studies [29,41]; 39% for back pain compared to 39% and 44% [30,41]; 23% for abdominal pain compared to 23%
and 18% [42]; and 19% for dizziness compared to 16–35% [7]. The response to our survey was similar compared with other symptom surveys in the general population [1,5,16,41], but the risk of selective nonresponse needs to be considered. In our study, responders were more often female, and a few years older than nonresponders. Additionally, nonresponders who provided a reason for not participating often indicated that they had no health problems. Analyses of response to subsequent mailings showed that there might be some selective nonresponse of persons with more anxiety or depression. However, the number of symptoms, and scores on perceived health were similar in early and late responders. Any selective nonresponse is unlikely to have affected the reported associations among health indicators, multiple symptoms, and perceived health, which are the main focus of this paper. We want to emphasize that we used cross-sectional data and cannot draw any conclusions regarding the direction or causality of the reported associations between health indicators, symptoms, and perceived health. For example, depressive symptoms may be a consequence of poor health and physical symptoms, but it is equally likely that depressive mood leads to more symptoms and poorer health perceptions. Longitudinal research is needed to look more closely at the temporal associations between multiple physical symptoms and health, and at the influence of other factors such as lifestyle, psychological factors, or childhood experiences on the development of such associations. Multiple symptoms and perceived health When investigating multiple symptoms, most researchers have studied consulters in primary or secondary care or have focused on patients diagnosed with chronic functional syndromes. Kroenke et al. [10] showed that among primary
270
D.A.W.M. van der Windt et al. / Journal of Psychosomatic Research 64 (2008) 265–274
Table 3 Association between characteristics of responders and number of physical symptoms in a community sample
Demographic variables Sex (% female) Age (years), mean (S.D.) Educational level (%) Primary Secondary College/university Paid work (%) Lifestyle factors Body mass index (%) b18 (underweight) 18 to 25 (normal weight) 25 to 30 (overweight) N30 (obese) Physically active, n (%) At least 3 times/week At least 30 min, ≥5 days/week Smoking (% yes) Alcohol consumption (%) b1 U/week 2–10 U/week N10 U/week Childhood experiences More often ill than other children (%) Admitted to hospital as a child (%) Family members with chronic illness (%) Psychological factors Anxiety (HADS, %) No (score 0–7) Possible anxiety (score 8–10) Probable anxiety (score N10) Depressive symptoms (HADS, %) No (score 0–7) Possible depression (score 8–10) Probable depression (N10) Sleeping problems (N50% of nights, %) Illness perceptions: not able to influence health (%) Perceived health (SF-36) Physical functioning (0–100) Role functioning, physical (0–100) Role functioning, emotional (0–100) Social functioning (0–100) Bodily pain (0–100) Mental health (0–100) Vitality (0–100) General health (0–100)
No symptoms (n=346)
1 or 2 (n=763)
3, 4, or 5 (n=889)
≥6 (n=449)
P value ⁎
42.5 52.6 (17.5)
52.0 50.0 (16.1)
63.0 48.9 (15.9)
72.2 49.8 (15.2)
b.001 .004
27.2 34.5 38.3 73.7
25.8 35.5 38.8 67.2
24.9 37.5 37.5 69.9
34.6 39.7 25.7 60.0
b.001
1.2 49.4 40.9 8.5
0.7 53.9 33.5 11.9
1.6 47.5 35.8 15.1
1.4 44.1 35.2 19.3
20.8 33.7 23.8
16.4 33.4 24.1
16.4 33.2 25.9
14.3 37.4 30.1
33.6 47.2 19.1
37.5 47.3 15.2
47.4 36.8 15.7
61.1 28.3 10.5
5.2 21.5 17.4
8.0 27.7 26.7
12.2 28.6 29.1
19.2 34.6 38.4
95.7 3.5 0.9
87.0 8.5 4.5
72.2 18.0 9.8
52.5 23.0 24.5
95.0 3.5 1.5 4.3 5.6
90.8 5.8 3.3 6.3 6.7
82.0 10.4 7.4 13.6 7.7
67.4 18.2 14.4 30.5 12.7
b.001 .001
93 97 95 93 96 83 77 77
86 82 89 86 80 79 68 71
80 (23) 69 (38) 78 (37) 77 (25) 69 (20) 71 (18) 58 (19) 62 (18)
67 47 61 65 54 63 47 50
b.001 b.001 b.001 b.001 b.001 b.001 b.001 b.001
.002
b.001
.115 .414 .097 b.001
b.001 .001 b.001 b.001
b.001
(14) (14) (18) (14) (10) (12) (14) (13)
(20) (32) (26) (19) (19) (14) (17) (16)
(26) (42) (44) (29) (21) (20) (19) (20)
⁎ ANOVA for continuous measures, or χ2 test for categorical measures.
care consulters the number of physical symptoms was highly predictive of functional impairment and psychiatric disorders. Studies among patients with functional bowel disorders, posttraumatic distress disorder, chronic widespread pain, and chronic fatigue syndrome have also shown that multiple physical symptoms are associated with psychological morbidity, poor illness perceptions, and childhood adversities [23,42–44]. We were particularly
interested to see whether the same correlations were of importance in a community-based sample, largely consisting of people reporting mild physical symptoms. Our results do confirm these findings: responders with multiple symptoms reported more negative childhood health experiences and more psychological distress. Additionally, with increasing number of symptoms we found more sleeping problems, higher BMI, and poorer scores for every dimension of health.
D.A.W.M. van der Windt et al. / Journal of Psychosomatic Research 64 (2008) 265–274
271
Table 4 Association between number of physical symptoms and perceived health (SF-1, score range 1–5, higher score indicating poorer health) No. of symptoms All responders (N=2438) 1 or 2 symptoms 3 to 5 symptoms ≥6 symptoms Health perceptions Able to influence health (n=1744) 1 or 2 symptoms 3 to 5 symptoms ≥6 symptoms Unable to influence health (n=193) 1 or 2 symptoms 3 to 5 symptoms ≥6 symptoms Family member with illness None (n=1739) 1 or 2 symptoms 3 to 5 symptoms ≥6 symptoms ≥1 family member (n=689) 1 or 2 symptoms 3 to 5 symptoms ≥6 symptoms
Mean difference (SF-1 ⁎ adjusted for age, sex)
95% CI
Mean difference (SF-1 ⁎ adjusted for age, sex, anxiety, depression)
95% CI
0.43 0.75 1.23
0.33–0.52 0.66–0.84 1.13–1.34
0.34 0.56 0.91
0.25–0.43 0.47–0.65 0.80–1.01
0.37 0.66 1.11
0.27–0.47 0.56–0.76 0.98–1.23
0.29 0.49 0.82
0.19–0.39 0.39–0.60 0.69–0.94
0.95 1.30 1.77
0.55–1.35 0.91–1.68 1.37–2.16
0.86 1.08 1.44
0.47–1.24 0.70–1.47 1.03–1.86
0.35 0.72 1.18
0.24–0.45 0.61–0.82 1.06–1.31
0.28 0.53 0.88
0.18–0.38 0.42–0.63 0.75–1.00
0.70 0.89 1.41
0.48–0.91 0.68–1.10 1.19–1.63
0.56 0.70 1.03
0.36–0.77 0.49–0.90 0.81–1.26
SF-1=first item Short-Form 36; CI=confidence interval. ⁎ Linear regression analysis; “no symptoms” is reference category.
Childhood health experiences We found that the association between multiple symptoms and perceived health was modified by childhood experiences with disease, but only when using overall health as the outcome measure. We asked our responders retrospectively about childhood health experiences and had no access to data that can be used to verify these reports. Recall bias is likely to be a larger problem in those with multiple symptoms. McBeth et al. [45] found that associations between chronic widespread pain and adverse childhood events were largely explained by differential recall. Mallen et al. [27] found that recalled childhood experiences of pain or illness were associated with current pain status in young adulthood. Young adults with pain remembered themselves as being comparatively ill as a child and aware of family members with pain. Families may have illnesses that are inherited, which may explain trends within family groups. However, the results could equally be related to learned behavior and modelling, which is particularly potent in childhood. In a prospective birth cohort, Hotopf et al. [25] showed a strong relationship between poor reported health of parents in 15-year-old children and symptoms later in adulthood. Unexplained symptoms during adulthood were also associated with abdominal pain in childhood but not with specific childhood disease. These results seemed to indicate that unexplained symptoms can be related to prior experience of family
illness and previous unexplained symptoms in the individual, reflecting a learned process whereby illness experience leads to more symptom awareness [25]. Anxiety The findings of other community and primary care studies support a close and linear relation between the number of bodily symptoms and measures of emotional distress. [10,46,47] In a prospective study among secondary care consulters, Jackson et al. [48] recently reported a significant association between the number of symptoms and poorer perceived health (SF-36), and that this association was independent of anxiety and depression. Our findings additionally show that anxiety modifies the relation between symptoms and health, with a stronger impact on physical functioning found in responders with more anxiety. People who are under stress may be quicker to ascribe physical symptoms to disease, rather than to normal physiology. Anxiety has also been reported to decrease pain threshold or pain tolerance [8,24,49]. Illness perceptions We found a stronger association between multiple symptoms and both physical functioning and perceived health among responders who felt they were unable to influence their own health. Poor perceptions about health
272
D.A.W.M. van der Windt et al. / Journal of Psychosomatic Research 64 (2008) 265–274
Table 5 Association between number of physical symptoms and physical functioning (SF-36, score range 0–100, higher scores indicating better functioning)
No. of symptoms All responders (n=2423) 1 or 2 symptoms 3 to 5 symptoms ≥6 symptoms Health perceptions Able to influence health (n=1744) 1 or 2 symptoms 3 to 5 symptoms ≥6 symptoms Unable to influence health (n=188) 1 or 2 symptoms 3 to 5 symptoms ≥6 symptoms Anxiety No anxiety (n=1837) 1 or 2 symptoms 3 to 5 symptoms ≥6 symptoms Possible/probable anxiety (n=559) 1 or 2 symptoms 3 to 5 symptoms ≥6 symptoms
Mean difference (physical functioning ⁎ adjusted for age, sex)
95% CI
Mean difference (physical functioning ⁎ adjusted for age, sex, anxiety, depression)
95% CI
−8.0 −14.3 −26.4
−10.4 to −5.5 −16.8 to −11.9 −29.1 to −23.6
−6.5 −10.7 −20.1
−9.0 to −4.1 −13.2 to −8.2 −23.1 to −17.2
−6.2 −11.0 −22.6
−8.6 to −3.7 −13.5 to −8.6 −25.5 to −19.6
−4.9 −8.4 −18.0
−7.3 to −2.4 −10.9 to −5.9 −21.1 to −14.9
−21.8 −29.0 −42.0
−35.1 to −8.5 −42.0 to −16,0 −55.4 to −28,7
−18.5 −21.3 −31.3
−31.2 to −5.7 −34.1 to −8.5 −45.0 to −17.5
−7.2 −12.9 −21.6
−9.6 to −4.8 −15.4 to −10.5 −24.7 to −18.5
−5.9 −10.2 −17.8
−8.2 to −3.6 −12.6 to −7.8 −20.8 to −14.8
−16.8 −21.1 −35.3
−29.0 to −4.6 −32.8 to −9.4 −47.1 to −23.5
−17.6 −20.5 −33.0
−29.4 to −5.8 −31.8 to −9.2 −44.4 to −21.6
⁎ Linear regression analysis; “no symptoms” is reference category.
and illness may increase attention to bodily symptoms and strengthen the attribution of such sensations to physical illness. These processes are a normal response to signs of illness in many people, but can reach disabling proportions in some, resulting in (undifferentiated) somatization disorder [24,50,51]. Although we did not measure increased attention to bodily symptoms, processes of somatization may partly explain our findings. Kirmayer and Robbins [52] described different forms of somatization: physical symptoms can be physiological components of anxiety or depression; normal bodily sensations or pathological events can be misinterpreted as signs of serious illness; or subjective physical symptoms may be present without underlying somatic or psychiatric illness. In our population, anxiety and depressive symptoms only partly explained the association between physical symptoms and health, which may indicate that— next to the presence of somatic disease—different forms of somatization can be of importance. Specific somatoform disorders (according to DSM criteria) are not common (prevalence about 1%), but undifferentiated somatization may affect as many as 20% of the population [53,54]. Conclusions The results of our community-based survey show that physical symptoms are common, although their impact on daily activities is limited in most people. However,
increasing number of symptoms—even if mild—are associated with increasing limitations in physical, emotional and social functioning, and poor perceived health. Acknowledgments We gratefully acknowledge Prof. Peter R. Croft, PhD, for his critical review of our manuscript and his useful suggestions. References [1] Pawlikowska T, Chalder T, Hirsch SR, Wallace P, Wright DJ, Wessely SC. Population based study of fatigue and general distress. BMJ 1994; 308:763–6. [2] Gallagher AM, Thomas JM, Hamilton WT, White PD. Incidence of fatigue symptoms and diagnoses presenting in UK primary care from 1990 to 2001. J R Soc Med 2004;97:571–5. [3] Reyes-Gibby CC, Mendoza TR, Wang S, Anderson KO, Cleeland CS. Pain and fatigue in community-dwelling adults. Pain Med 2003;4: 231–7. [4] Papageorgiou AC, Silman AJ, Macfarlane GJ. Chronic widespread pain in the population: a 7-year follow-up study. Ann Rheum Dis 2003; 61:1071–4. [5] Boardman HF, Thomas E, Croft PR, Millson DS. Epidemiology of headache in an English district. Cephalalgia 2003;23:129–37. [6] Hillila MT, Farkkila MA. Prevalence of irritable bowel syndrome according to different diagnostic criteria in a non-selected adult population. Aliment Pharmacol Ther 2004;20:339–45. [7] Sloane PD, Coeytaux RR, Beck RS, Dallara J. Dizziness: state of the science. Ann Intern Med 2001;134:823–32.
D.A.W.M. van der Windt et al. / Journal of Psychosomatic Research 64 (2008) 265–274 [8] Barski AJ, Borus JF. Somatization and medicalization in the era of managed care. JAMA 1995;274:1931–4. [9] Kroenke K, Price RK. Symptoms in the community. Prevalence, classification, and psychiatric comorbidity. Arch Intern Med 1993;153: 2474–80. [10] Kroenke K, Spitzer RL, Williams JB, Linzer M, Hahn SR, deGruy FV, Brody D. Physical symptoms in primary care. Predictors of psychiatric disorders and functional impairment. Am Fam Med 1994;3:774–9. [11] Katon W, Sullivan M, Walker E. Medical symptoms without identified pathology: relationship to psychiatric disorders, childhood and adult trauma, and personality traits. Ann Intern Med 2001;134:917–25. [12] Macfarlane GJ, Hunt IM, McBeth J, Papageorgiou AC, Silman AJ. Chronic widespread pain in the community: influences on health care seeking behaviour. J Rheumatol 1999;26:413–9. [13] Little P, Somerville J, Williamson I, Warner G, Moore M, Wiles R, George S, Smith A, Peveler R. Psychosocial, lifestyle, and health status variables in predicting high attendance among adults. Br J Gen Pract 2001;51:987–94. [14] Reid S, Wessely S, Crayford T, Hotopf M. Frequent attenders with medically unexplained symptoms: service use and costs in secondary care. Br J Psychiatry 2002;180:248–53. [15] White KP, Speechley M, Harth M, Ostbye T. The London Fibromyalgia Study: the prevalence of fibromyalgia syndrome in London, Ontario. J Rheumatol 1999;26:1570–6. [16] Huibers MJ, Kant IJ, Swaen GM, Kasl SV. Prevalence of chronic fatigue syndrome-like caseness in the working population: results from the Maastricht cohort study. Occup Environ Med 2004;61:464–6. [17] Boyce PM, Talley NJ, Burke C, Koloski NA. Epidemiology of the functional gastrointestinal disorders diagnosed according to Rome II criteria: an Australian population-based study. Intern Med J 2006;36: 28–36. [18] Buskila D, Press J. Neuroendocrine mechanisms in fibromyalgiachronic fatigue. Best Pract Res Clin Rheumatol 2001;15:747–58. [19] McBeth J, Chiu YH, Silman AJ, Ray D, Morriss R, Dickens C, Gupta A, Macfarlane GJ. Hypothalamic-pituitary-adrenal stress axis function and the relationship with chronic widespread pain and its antecedents. Arthritis Res Ther 2005;7:R992–R1000. [20] Griep EN, Boersma JW, Lentjes EG, Prins AP, van der Korst JK, de Kloet ER. Function of the hypothalamic-pituitary-adrenal axis in patients with fibromyalgia and low back pain. J Rheumatol 1998;25: 1374–81. [21] Aaron LA, Bichwald D. A review of the evidence for overlap among unexplained clinical conditions. Ann Intern Med 2001;134:868–81. [22] Nimnuan C, Hotopf M, Wessely S. Medically unexplained symptoms: an epidemiological study in seven specialities. J Psychosom Res 2001; 51:361–7. [23] Henningsen P, Zimmermann T, Sattel H. Medically unexplained physical symptoms, anxiety, and depression: a meta-analytic review. Psychosom Med 2003;65:528–33. [24] Kirmayer LJ, Looper KJ. Abnormal illness behaviour: physiological, psychological and social dimensions of coping with distress. Curr Opin Psychiatry 2006;19:54–60. [25] Hotopf M, Mayou R, Wadsworth M, Wessely S. Childhood risk factors for adults with medically unexplained symptoms: results from a national birth cohort study. Am J Psychiatry 1999;156:1796–800. [26] Little P, Somerville J, Williamson I, Warner G, Moore M, Wiles R, George S, Smith A, Peveler R. Family influences in a cross-sectional survey of higher child attendance. Br J Gen Pract 2001;51:977–81, 84. [27] Mallen C, Peat G, Thomas E, Croft P. Is chronic pain in adulthood related to childhood factors? A population-based case-control study of young adults. J Rheumatol 2006;33:2286–90. [28] van der Linden MW, Westert GP, de Bakker DH, Schellevis FG. 2nd National Study of Health and Illness (in Dutch). Utrecht: NIVEL/ RIVM; 2004. [29] Pope DP, Croft PR, Pritchard CM, Silman AJ. Prevalence of shoulder pain in the community: the influence of case definition. Ann Rheum Dis 1997;56:308–12.
273
[30] Papageorgiou AC, Croft PR, Ferry S, Jayson MI, Silman AJ. Estimating the prevalence of low back pain in the general population: evidence from the South Manchester Back Pain Survey. Spine 1995; 20:1889–94. [31] Thomas E, Wilkie R, Peat G, Hill S, Dziedzic K, Croft P. The North Staffordshire Osteoarthritis Project-NorStOP: prospective, 3-year study of the epidemiology and management of clinical osteoarthritis in a general population of older adults. BMC Musculoskelet Disord 2004;5:2. [32] Ware JE, Sherbourne CD. The MOS 36-item short-form health survey (SF-36): I. Conceptual framework and item selection. Med Care 1992; 30:473–83. [33] Aaronson NK, Muller M, Cohen PD, Essink-Bot ML, Fekkes M, Sanderman R, Sprangers MA, Te Velde VA, Verrips E. Translation, validation, and norming of the Dutch language version of the SF-36 Health Survey in community and chronic disease populations. J Clin Epidemiol 1998;51:1055–68. [34] Kemper H, Ooijendijk W, Stiggelbout M. Consensus about the Dutch recommendation for physical activity to promote health (in Dutch). Tijdschr Gezondheidswet 2000;78:180–3. [35] Pate RR, Pratt M, Blair SN, Haskell WL, Macera CA, Bouchard C, Buchner D, Ettinger W, Heath GW, King AC. Physical activity and public health. A recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine. JAMA 1995;273:402–7. [36] American College of Sports Medicine Position Stand. The recommended quantity and quality of exercise for developing and maintaining cardiorespiratory and muscular fitness in healthy adults. Med Sci Sports Exerc 1990;22:265–74. [37] Zigmund AS, Snaith RP. The Hospital Anxiety and Depression Scale. Acta Psychiatr Scand 1983;67:361–70. [38] Spinhoven P, Ormel J, Sloekers PP, Kempen GI, Speckens AE, Van Hemert AM. A validation study of the Hospital Anxiety and Depression Scale (HADS) in different groups of Dutch subjects. Psychol Med 1997;27:363–70. [39] Bjelland I, Dahl AA, Haug TT, Neckelmann D. The validity of the Hospital Anxiety and Depression Scale. An updated literature review. J Psychosom Res 2002;52:69–77. [40] Moss-Morris R, Weinman J, Petrie KJ, Horne R, Cameron LD, Buick D. The Revised Illness Perception Questionnaire (IPQ-R). Psychol Health 2002;7:1–16. [41] Picavet HSJ, Schouten JSAG. Musculoskeletal pain in the Netherlands: prevalences, consequences, and risk groups, the DMC3 study. Pain 2003;102:167–78. [42] Koloski NA, Talley NJ, Boyce PM. Epidemiology and health care seeking in the functional GI disorders: a population-based study. Am J Gastroenterol 2002;97:2290–9. [43] Engel CC, Liu X, McCarthy BD, Miller RF, Ursano R. Relationship of physical symptoms to post traumatic stress disorder among veterans seeking care for gulf war-related health concerns. Psychosom Med 2000;62:739–45. [44] Imbierowitz K, Egle UT. Childhood adversities in patients with fibromyalgia and somatoform pain disorder. Eur J Pain 2003;7: 113–9. [45] McBeth J, Morris S, Benjamin S, Silman AJ, Macfarlane GJ. Associations between adverse events in childhood and chronic widespread pain in adulthood: are they explained by differential recall? J Rheumatol 2001;28:2305–9. [46] Wessely S, Chalder T, Hirsch S, Wallace P, Wright D. Psychological symptoms, somatic symptoms, and psychiatric disorder in chronic fatigue and chronic fatigue syndrome: a prospective study in the primary care setting. Am J Psychiatry 1996;153:1050–9. [47] Simon G, Gater R, Kisely S, Pccinelli M. Somatic symptoms of distress: an international primary care study. Psychosom Med 1996;58: 481–8. [48] Jackson J, Fiddler M, Kapur N, Wells A, Tomenson B, Creed F. Number of bodily symptoms predicts outcome more accurately than
274
D.A.W.M. van der Windt et al. / Journal of Psychosomatic Research 64 (2008) 265–274
health anxiety in patients attending neurology, cardiology, and gastroenterology clinics. J Psychosom Res 2006;60:357–63. [49] Jones A, Zachariae R. Gender, anxiety, and experimental pain sensitivity: an overview. J Am Med Womens Assoc 2002;57:91–4. [50] Brown RJ. Psychological mechanisms of medically unexplained symptoms. Psychol Bull 2004;130:793–812. [51] Escobar JI, Hoyos-Nervi C, Gara M. Medically unexplained symptoms in medical practice. Environ Health Perspect 2002;110(suppl 4): 631–6.
[52] Kirmayer LJ, Robbins JM. Three forms of somatization in primary care: prevalence, co-occurrence, and sociodemographic characteristics. J Nerv Ment Dis 1991;179:647–55. [53] Grabe HJ, Meyer C, Hapke U, Rumpf HJ, Freyberger HJ, Dilling H, John U. Specific somatoform disorders in the general population. Psychosomatic 2003;44:304–11. [54] Karvonen JT, Veijola J, Jokelainen J, Laksy K, Jarvelin MR, Joukamaa M. Somatization disorder in young adult population. Gen Hosp Psych 2004;26:9–12.