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Neck pain in adolescence. A 4-year follow-up of pain-free preadolescents
Pain 110 (2004) 427–431 www.elsevier.com/locate/pain
Neck pain in adolescence. A 4-year follow-up of pain-free preadolescents Minna Sta˚hla, Marja Mikkelssonb,*, Hannu Kautiainenb, Arja Ha¨kkinena, Jari Ylinena, Jouko J. Salminenc a
Department of Physical and Rehabilitation Medicine, Jyva¨skyla¨ Central Hospital, Keskussairaalantie 19, 40620 Jyva¨skyla¨, Finland b The Rheumatism Foundation Hospital, Pikija¨rventie 1, 18120 Heinola, Finland c Department of Physical and Rehabilitation Medicine, University Hospital of Turku, P.O. Box 52, 20520 Turku, Finland Received 15 December 2003; received in revised form 9 April 2004; accepted 19 April 2004
Abstract The main aim of this study was to explore the occurrence and changes of neck pain in pain-free preadolescents. The evaluation was performed at 1- and 4-year follow-ups. Of the pain-free preadolescents, 366 (71.9%) completed structured pain questionnaires at 1 and 4 years. The occurrence of neck pain at least once a month was 21.3 and 43.4% and at least once a week was 6.3 and 19.4%. Sex difference was found only at the 4-year follow-up, when subjects were 13 – 16-year-old. Neck pain was then more common among girls than boys ðP , 0:001Þ: The intensity of pain increased with the frequency of pain ðP , 0:001Þ: Of those with neck pain, 28% had used painkillers. The proportion increased with the frequency of neck pain ðP ¼ 0:054Þ: Neck pain occurred more often with some other musculoskeletal pain than as a single pain. The frequency of neck pain correlated with the frequency of headache (r ¼ 0:39 [95% confidence interval (CI), 0.30 –0.47]) and with the disability (r ¼ 0:26 [95% CI, 0.16– 0.35]). This study strengthens the results of the previous cross-sectional studies that occurrence of neck pain increases with age, and that neck pain becomes more common among girls than boys in adolescence. Among preadolescents who were originally pain-free, there was only a small proportion who reported frequent neck pain at both 1 and 4 years. It also showed that the frequency of neck pain reflects the intensity of pain fairly well. q 2004 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved. Keywords: Neck pain; Children; Adolescent; Pain intensity; Musculoskeletal pain; Headache
1. Introduction Musculoskeletal pain disorders such as neck pain are common public health problems among today’s working population in industrialized countries (Picavet and Schouten, 2003). It not only has an economic impact (Meerding et al., 1998), but also produces a lot of pain and suffering to people (Badley et al., 1994). The lifetime prevalence of neck pain in adults has been reported to range from 26 to 71% (Coˆte´ et al., 1998; Guez et al., 2002; Lau et al., 1996; Ma¨kela¨ et al., 1991), increasing with age up to the age of 60 –70 (Bovim et al., 1994; Ma¨kela¨ et al., 1991). Neck pain is significantly more common among women than men (Bovim et al., 1994; Coˆte´ et al., 1998; Guez et al., * Corresponding author. Address: Department of Physical and Rehabilitation Medicine, The Rheumatism Foundation Hospital, Pikija¨rventie 1, 18120 Heinola, Finland. Tel.: þ 358-3-849-1532/50-5324202; fax: þ 358-3-849-1516. E-mail address: [email protected] (M. Mikkelsson).
2002; Ma¨kela¨ et al., 1991; Palmer et al., 2001). The 1-year cumulative incidence of neck pain is 18% (Croft, 2001). Chronic neck pain syndrome was suffered by 10 –16% of men and 13– 22% of women (Bovim et al., 1994; Guez et al. 2002; Ma¨kela¨ et al., 1991). In the last decade, neck pain has become a growing health problem among adolescents (Hakala et al., 2002). Reports of WHO Cross-National Study support these findings (King et al., 1996). The prevalence of neck pain increases with age and symptoms are more common among girls than boys analogously to adult population (Feldman et al., 2002; Niemi et al., 1996; Smedbra˚ten et al., 1998; Vikat et al., 2000). A Finnish survey had already showed that preadolescent children reported neck pain, and it was the second common pain symptom after lower limb pain (Mikkelsson et al., 1997). Neck pain was also the most persistent musculoskeletal pain symptom at the 1-year follow-up, especially among girls (Mikkelsson et al., 1997, 1999). Another Finnish study showed association between
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neck – shoulder symptoms and episodic tension-type headache in children (Anttila et al., 2002). It might be important to recognise and treat neck pain as early as possible to prevent chronic musculoskeletal pain problems (Hertzberg, 1983). There is a need for longitudinal epidemiological studies that extend to childhood and adolescence (Zitting, 1998). In order to create primary prevention programs for musculoskeletal pain disorders, we should know not only more about the risk factors, but also at what age these problems usually begin and possibly become chronic. The objective of this study was to investigate the occurrence and changes of neck pain and co-occurrence of other musculoskeletal pain in the group of initially pain-free (not any musculoskeletal pain at the baseline) preadolescents. The frequency and intensity of pain symptoms (Perquin et al., 2000), use of painkillers, and association of headache and subjective disability were also studied at the 4-year follow-up.
2. Subjects and methods 2.1. Baseline study The study took place in Lahti, a town of 94,827 inhabitants in southern Finland. At baseline, 19 primary schools took part in the study. In March 1995, total amount of 1756 third grade pupils, mean age 9.8 [standard deviation (SD) 0.3 (range 9 –10)] and fifth grade pupils, mean age 11.8 [SD 0.3 (range11 – 12)] completed a pre-tested pain questionnaire (Mikkelsson et al., 1997), which included site-spesific questions of pain in different areas of the body. This was linked with a five-level frequency classification (pain seldom or never, once a month, once a week, more than once a week, almost daily). Children were asked pain symptoms from the preceding Christmas until the day of study (period of 3 months). At baseline, 509 of the 1756 (29.0%) preadolescents seldom reported any musculoskeletal pain or never (pain-free subgroup). 2.2. Follow-up The follow-ups were conducted 1 and 4 years later in March 1996 and 1999 in the same way as in 1995. Again the pain symptoms asked concerned the period of the preceding 3 months. At the 4-year follow-up, the subjects were seventh (13 – 14-year-old) and ninth (15 – 16-year-old) grade students. There were 366 (71.9%) children who belonged to the pain-free subgroup at baseline and responded to the questionnaire both at the 1- and 4-year follow-ups. Of them, 189 (51.6%) were girls and 177 (48.4%) boys. The number of drop-outs was 143 (52 girls and 91 boys). At baseline, 83 (58%) of the drop-outs were in the third class and 60 (42%) in the fifth class. Non-participation in the follow-ups involved reasons like being absent on the day of testing, changing schools, moving away or refusing to participate.
At 4-year follow-up, the questionnaire included the same questions as at baseline. In addition, the intensity of pain in different areas of the body was elicited by site-spesific visual analogue scales (VAS) 0 – 100 mm. The frequency of headache was assessed by a five-level frequency classification (headache seldom or never, once a month, once a week, more than once a week, almost daily). The subjective pain-induced disability was calculated from answers to the following statements (maximum five points): (1) I have difficulty in falling asleep because of pain and aches and/or pain and aches disturb my sleep; (2) I have difficulty in sitting during a lesson due to pain; (3) Pain disturbs me if I walk more than 1 km; (4) Pain disturbs me during physical exercise class; and (5) Pain and aches disturb my hobbies. Use of painkillers was asked dichotomously (yes/no). 2.3. Statistical methods The descriptive variables are shown in frequencies, percentages, mean and SD. The 95% confidence intervals (CI) of probabilities were calculated with Clopper–Pearson method. The difference between groups among categorical variables was analysed by Pearson x2 test or Fisher – Freeman – Halton test. The linearity between pain and use of painkillers was calculated by the Cochrane –Armitage trend test. The association between pain frequency and intensity was analysed by analysis of variance. Spearman’s r was used for the nonparametric correlations. To apply the associations of neck pain and other variables, maximum-likelihood ordered logit estimation with forward stepwise procedure was used.
3. Results 3.1. Occurrence and changes of neck pain at the 1- and 4-year follow-ups At the 1-year follow-up, neck pain at least once a month was reported by 78 [21.3% (95% CI, 17.2– 25.9)] children, 45 [23.8% (18.3 –30.4)] girls and 33 [18.6% (13.6 –25.0)] boys ðP ¼ 0:23Þ: Neck pain at least once a week was reported by 23 [6.3% (95% CI, 4.0 –9.3]) children. At the 4-year follow-up, neck pain at least once a month was reported by 159 [43.4% (95% CI, 38.3 – 48.7)] children, 108 [57.1% (49.8 –64.3)] girls and 51 [28.8% (22.3 –36.1)] boys ðP , 0:001Þ: Neck pain at least once a week was reported by 71 [19.4% (95% CI, 15.5– 23.8)] adolescents. Fig. 1 shows the changes of neck pain from the baseline pain-free situation to the 1- and 4-year followups. Neck pain at least once a month was indicated in 115 (31.5%) earlier pain-free preadolescents at the 4-year follow-up. On the other hand, 34 out of 78 (43.6%) children who had neck pain at the 1-year follow-up became pain-free at the 4-year follow-up. Of those who
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3.2. Pain intensity and use of painkillers at the 4-year follow-up Mean (SD) intensity of pain was 36 (14) mm among those who reported neck pain once a week and 62 (27) mm among those who reported neck pain almost daily. The intensity of pain increased with the frequency of pain (P , 0:001 for linear trend). Of the adolescents with neck pain, 44 (28%) had used painkillers to relieve their pain. The proportion of painkiller users increased with the frequency of neck pain ðP ¼ 0:054Þ (Table 1).
Fig. 1. Occurrence and changes of neck pain among originally pain-free preadolescents at the 1- and 4-year follow-ups. Percentages in 1996 and 1999 refer to percentage of original 366 pain-free children. Open bar shows no neck pain, dotted neck pain once a month and black bar at least once a week.
Table 1 Intensity of pain and use of painkillers at the 4-year follow-up Descriptive variables
Neck pain frequency
P for linear trend
Once Once More than Almost a month a week once a week daily ðN ¼ 86Þ ðN ¼ 51Þ ðN ¼ 13Þ ðN ¼ 7Þ Pain intensity 25 (16) (VAS), mean (SD) Number of 19 (22) children having used pain killers (%) a b
36 (14)
55 (24)
62 (27)
17 (33)
5 (38)
3 (43)
3.3. Co-occurrence of other musculoskeletal pain with neck pain At the 1-year follow-up, neck pain at least once a month as a single musculoskeletal pain symptom had occurred in 28 children (7.6%), while the other 50 children (13.7%) reported neck pain combined with some other musculoskeletal pain (multiple pain). At the 4-year follow-up, neck pain at least once a month as a single pain had occurred in 35 (9.5%) children, while the other 124 (33.9%) reported multiple pain. Table 2 shows the co-occurrence of other musculoskeletal pain by neck pain frequency categories. In all neck pain frequency categories lower limb pain was the most common other musculoskeletal pain in both follow-ups.
,0.001a
3.4. Neck pain associated with headache and disability at the 4-year follow-up 0.054b
Analysis of variance (ANOVA). Cochran–Armitage trend test.
were pain-free at baseline, there were 44 (12.0%), who reported any neck pain at both follow-ups. Only seven (1.9%) children suffered from weekly neck pain at both follow-ups.
At the 4-year follow-up, headache at least once a month was reported by 238 (65.0%) and at least once a week by 91 (24.9%) adolescents. Only 14 (3.8%) adolescents had the highest subjective pain-induced disability index 3– 5/5 and 79 (21.6%) had disability index 1– 2/5. Most of the adolescents (74.6%) reported no disability. The frequency of neck pain correlated with the frequency of headache [r ¼ 0:39 (95% CI, 0.30 – 0.47)], and with disability [r ¼ 0:26 (95% CI, 0.16 – 0.35)].
Table 2 Co-occurrence of other musculoskeletal pain with neck pain in 1- and 4-year follow-ups
Upper limb Chest Lower limb Upper back Lower back Buttock
Neck pain frequency in 1-year follow-up, N (%)
Neck pain frequency in 4-year follow-up, N (%)
No pain ðN ¼ 280Þ
Once a month ðN ¼ 55Þ
At least once a week ðN ¼ 23Þ
No pain ðN ¼ 207Þ
Once a month ðN ¼ 88Þ
At least once a week ðN ¼ 71Þ
9 (3.1) 11 (3.8) 50 (17.4) 8 (2.8) 9 (3.1) 2 (0.7)
7 (12.7) 8 (14.5) 25 (45.6) 9 (16.4) 8 (14.5) 7 (12.7)
5 7 11 5 3 2
24 (11.6) 14 (6.8) 57 (27.5) 12 (5.8) 36 (17.4) 4 (1.9)
18 (20.5) 17 (19.3) 43 (48.9) 22 (25.0) 33 (37.5) 5 (5.7)
27 14 42 34 37 11
(21.7) (30.4) (47.8) (21.7) (13.0) (8.7)
(38.0) (19.7) (59.0) (47.9) (52.1) (15.5)
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3.5. The relationship between neck pain and other variables The relationship between neck pain and co-occurrence of other pains, age, gender, use of pain medication, headache and disability was explored by forward stepwise ordered logit estimation. The following variables entered into the model: upper back [OR ¼ 3.97 (95% CI, 2.72 –5.80)], headache [OR ¼ 1.75 (1.39 – 2.20)], girl [OR ¼ 2.76 (1.74 –4.37) and lower limb [OR ¼ 1.73 (1.33 – 2.26)].
4. Discussion To our knowledge the present study is the first prospective follow-up of pain-free preadolescents. We found that 21% of at the baseline pain-free preadolescents reported neck pain at the 1-year follow-up. Of those, who were still pain-free at the 1-year follow-up, 32% reported neck pain at the 4-year follow-up. In the recent adult study, 1-year cumulative incidence of neck pain was 18% (Croft et al., 2001). Feldman et al. (2002) found the cumulative annual incidence of neck pain at least once a week 10% among adolescents. In our study 6.3% had neck pain at least once a week at the 1-year follow-up. Of those, who were pain-free at the 1-year follow-up, 16% reported weekly neck pain at the 4-year follow-up. In our study the true annual cumulative incidence cannot be estimated, since we asked neck pain only during the preceding 3 months at the 1 and 4-year follow-up points, and it does not cover the whole follow-up time. Still our results are quite close to Feldman’s findings. The ‘1-year incidence’ was little less in our study, but can be explained by the difference in age group studied (our participants were preadolescents at the 1-year follow-up) and also by the fact that we asked symptoms during the preceeding 3 months not during the whole year. Hakala et al. (2002) published increasing prevalence rates in adolescents’ neck pain in the 1990s. Our study showed, however, that nearly half of the children with neck pain at the 1-year follow-up were pain-free at the 4-year follow-up. This indicates that neck pain symptoms fluctuate. Increasing prevalence rates in adolescence do not mean that symptoms persist among the same children. In this study, 12% reported neck pain at both follow-ups. Only 1.9% had symptoms at least once a week at both follow-ups. This is a group that probably would need a clinical attention already as preadolescents to prevent chronic pain and disability later in their lives. In preadolescence, no difference between genders was found in either the occurrence of neck pain, or in other musculoskeletal pain symptoms (Mikkelsson et al., 1997). In adolescence, however, neck pain was significantly more common among girls (13 – 16-year-olds). Similar results have been reported earlier in several studies of neck and low back pain (Balague´ et al., 1999; Hakala et al., 2002; Niemi et al., 1996; Smedbra˚ten et al., 1998; Vikat et al., 2000), further strengthening the evidence that girls are generally
more prone to any pain in adolescence. This suggests that some etiological factors might be related to sex-related hormonal changes and differences in musculoskeletal systems, while others might relate to differences in behavioural factors. The basic problem concerns, not only the underlying pathology and mechanism of pain, but factors influencing a subject’s response to symptoms. Boys might have a tendency to deny or girls to overestimate their symptoms at puberty. In order to determine frequency of pain episodes and severity of pain, a need for longitudinal studies has been noted (Bovim et al., 1994; McGrath, 1987). In this study, the intensity of pain was measured by VAS, and a linear association between the intensity and the frequency of neck pain was found. The pain intensity was low to moderate among those who reported neck pain once a week, but moderate to severe among those having symptoms more than once week. Thus, the frequency of pain reflected the intensity of pain fairly well. In this study, most adolescents with neck pain seemed to handle it without medication or significant disability, but a minority suffered from severe pain and used medication. The use of painkillers was associated with high pain frequency. We found that neck pain occurred more often with some other musculoskeletal pain than as a single pain. Co-occurrence of other musculoskeletal pain with neck pain indicates that some factors might be common to different musculoskeletal symptoms without specificity to neck pain. In fact, Mikkelsson et al. (1999) has earlier reported that 20% of children with neck pain at baseline reported widespread pain after 1-year follow-up. In our study, lower limb pain was the most common other pain with neck pain in both followups. Lower limb pain has earlier found to be the most common musculoskeletal pain among children and adolescents (Mikkelsson et al., 1997; Perquin et al., 2000; Roth-Isigkeit et al., 2003). Back pain co-occurred in half of the adolescents with neck pain at least once a week at the 4-year follow-up. The co-morbidity of neck and low back pain was found earlier in 12 –18-year-old Finnish school children (Vikat et al., 2000). Feldman et al. (2002) found that neck and upper back were the most common sites of pain in adolescents. In the 1990s, the new information and communication technology had a tremendous impact on adolescents’ everyday life. We may speculate that both static postures and static muscular activation patterns in computer using could explain partly this high co-occurrence between neck and back pain in adolescents. When we explored the relationship between neck pain and other variables in the study, we found that girls who have upper back pain, headache and limb pain are most likely to also have neck pain. The strength of this study is its fairly long follow-up. Also the fluctuation due to seasonal variation was precluded since the follow-ups were done at wintertime as at baseline (Feldman et al., 2002). Although the responding rate was quite good (71.9%), among the drop-outs, there were more
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boys than girls (91 vs. 52). We do not know the exact reasons for that and therefore, the impact on results is speculative. Another weakness of the study is that the disability questions were not specific for neck pain and may not describe the effects of neck pain on everyday life. In addition, we studied a defined subgroup of original sample and there are limitations in extrapolating the findings to the general literature. In summary, our results further strengthen the evidence that unspecific neck pain is common already in early adolescence, especially in girls, and even in subjects who had been asymptomatic in preadolescence. Factors contributing to this are unknown and further studies are needed to explore them. The co-occurrence of different musculoskeletal pain symptoms suggests that some determinants might be common to them. Although neck pain symptoms are common, they seem to fluctuate and minority represents chronic, persistent neck pain. However, good prognosis can be generalized only to this studied pain-free subgroup. Finally, our results indicate that in community studies the definition of neck pain by frequency also reflects the intensity of pain fairly well.
Acknowledgements We thank Mrs Tuija Sulonen, RN, for assistance in collecting the data at follow-up. Funding. This study was supported by Signe and Ane Gyllenberg’s Foundation, by the Medical Research Fund of the Rheumatism Foundation Hospital, the University Hospital of Turku and Jyva¨skyla¨ Central Hospital.
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Neck pain in adolescence. A 4-year follow-up of pain-free preadolescents Minna Sta˚hla, Marja Mikkelssonb,*, Hannu Kautiainenb, Arja Ha¨kkinena, Jari Ylinena, Jouko J. Salminenc a
Department of Physical and Rehabilitation Medicine, Jyva¨skyla¨ Central Hospital, Keskussairaalantie 19, 40620 Jyva¨skyla¨, Finland b The Rheumatism Foundation Hospital, Pikija¨rventie 1, 18120 Heinola, Finland c Department of Physical and Rehabilitation Medicine, University Hospital of Turku, P.O. Box 52, 20520 Turku, Finland Received 15 December 2003; received in revised form 9 April 2004; accepted 19 April 2004
Abstract The main aim of this study was to explore the occurrence and changes of neck pain in pain-free preadolescents. The evaluation was performed at 1- and 4-year follow-ups. Of the pain-free preadolescents, 366 (71.9%) completed structured pain questionnaires at 1 and 4 years. The occurrence of neck pain at least once a month was 21.3 and 43.4% and at least once a week was 6.3 and 19.4%. Sex difference was found only at the 4-year follow-up, when subjects were 13 – 16-year-old. Neck pain was then more common among girls than boys ðP , 0:001Þ: The intensity of pain increased with the frequency of pain ðP , 0:001Þ: Of those with neck pain, 28% had used painkillers. The proportion increased with the frequency of neck pain ðP ¼ 0:054Þ: Neck pain occurred more often with some other musculoskeletal pain than as a single pain. The frequency of neck pain correlated with the frequency of headache (r ¼ 0:39 [95% confidence interval (CI), 0.30 –0.47]) and with the disability (r ¼ 0:26 [95% CI, 0.16– 0.35]). This study strengthens the results of the previous cross-sectional studies that occurrence of neck pain increases with age, and that neck pain becomes more common among girls than boys in adolescence. Among preadolescents who were originally pain-free, there was only a small proportion who reported frequent neck pain at both 1 and 4 years. It also showed that the frequency of neck pain reflects the intensity of pain fairly well. q 2004 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved. Keywords: Neck pain; Children; Adolescent; Pain intensity; Musculoskeletal pain; Headache
1. Introduction Musculoskeletal pain disorders such as neck pain are common public health problems among today’s working population in industrialized countries (Picavet and Schouten, 2003). It not only has an economic impact (Meerding et al., 1998), but also produces a lot of pain and suffering to people (Badley et al., 1994). The lifetime prevalence of neck pain in adults has been reported to range from 26 to 71% (Coˆte´ et al., 1998; Guez et al., 2002; Lau et al., 1996; Ma¨kela¨ et al., 1991), increasing with age up to the age of 60 –70 (Bovim et al., 1994; Ma¨kela¨ et al., 1991). Neck pain is significantly more common among women than men (Bovim et al., 1994; Coˆte´ et al., 1998; Guez et al., * Corresponding author. Address: Department of Physical and Rehabilitation Medicine, The Rheumatism Foundation Hospital, Pikija¨rventie 1, 18120 Heinola, Finland. Tel.: þ 358-3-849-1532/50-5324202; fax: þ 358-3-849-1516. E-mail address: [email protected] (M. Mikkelsson).
2002; Ma¨kela¨ et al., 1991; Palmer et al., 2001). The 1-year cumulative incidence of neck pain is 18% (Croft, 2001). Chronic neck pain syndrome was suffered by 10 –16% of men and 13– 22% of women (Bovim et al., 1994; Guez et al. 2002; Ma¨kela¨ et al., 1991). In the last decade, neck pain has become a growing health problem among adolescents (Hakala et al., 2002). Reports of WHO Cross-National Study support these findings (King et al., 1996). The prevalence of neck pain increases with age and symptoms are more common among girls than boys analogously to adult population (Feldman et al., 2002; Niemi et al., 1996; Smedbra˚ten et al., 1998; Vikat et al., 2000). A Finnish survey had already showed that preadolescent children reported neck pain, and it was the second common pain symptom after lower limb pain (Mikkelsson et al., 1997). Neck pain was also the most persistent musculoskeletal pain symptom at the 1-year follow-up, especially among girls (Mikkelsson et al., 1997, 1999). Another Finnish study showed association between
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neck – shoulder symptoms and episodic tension-type headache in children (Anttila et al., 2002). It might be important to recognise and treat neck pain as early as possible to prevent chronic musculoskeletal pain problems (Hertzberg, 1983). There is a need for longitudinal epidemiological studies that extend to childhood and adolescence (Zitting, 1998). In order to create primary prevention programs for musculoskeletal pain disorders, we should know not only more about the risk factors, but also at what age these problems usually begin and possibly become chronic. The objective of this study was to investigate the occurrence and changes of neck pain and co-occurrence of other musculoskeletal pain in the group of initially pain-free (not any musculoskeletal pain at the baseline) preadolescents. The frequency and intensity of pain symptoms (Perquin et al., 2000), use of painkillers, and association of headache and subjective disability were also studied at the 4-year follow-up.
2. Subjects and methods 2.1. Baseline study The study took place in Lahti, a town of 94,827 inhabitants in southern Finland. At baseline, 19 primary schools took part in the study. In March 1995, total amount of 1756 third grade pupils, mean age 9.8 [standard deviation (SD) 0.3 (range 9 –10)] and fifth grade pupils, mean age 11.8 [SD 0.3 (range11 – 12)] completed a pre-tested pain questionnaire (Mikkelsson et al., 1997), which included site-spesific questions of pain in different areas of the body. This was linked with a five-level frequency classification (pain seldom or never, once a month, once a week, more than once a week, almost daily). Children were asked pain symptoms from the preceding Christmas until the day of study (period of 3 months). At baseline, 509 of the 1756 (29.0%) preadolescents seldom reported any musculoskeletal pain or never (pain-free subgroup). 2.2. Follow-up The follow-ups were conducted 1 and 4 years later in March 1996 and 1999 in the same way as in 1995. Again the pain symptoms asked concerned the period of the preceding 3 months. At the 4-year follow-up, the subjects were seventh (13 – 14-year-old) and ninth (15 – 16-year-old) grade students. There were 366 (71.9%) children who belonged to the pain-free subgroup at baseline and responded to the questionnaire both at the 1- and 4-year follow-ups. Of them, 189 (51.6%) were girls and 177 (48.4%) boys. The number of drop-outs was 143 (52 girls and 91 boys). At baseline, 83 (58%) of the drop-outs were in the third class and 60 (42%) in the fifth class. Non-participation in the follow-ups involved reasons like being absent on the day of testing, changing schools, moving away or refusing to participate.
At 4-year follow-up, the questionnaire included the same questions as at baseline. In addition, the intensity of pain in different areas of the body was elicited by site-spesific visual analogue scales (VAS) 0 – 100 mm. The frequency of headache was assessed by a five-level frequency classification (headache seldom or never, once a month, once a week, more than once a week, almost daily). The subjective pain-induced disability was calculated from answers to the following statements (maximum five points): (1) I have difficulty in falling asleep because of pain and aches and/or pain and aches disturb my sleep; (2) I have difficulty in sitting during a lesson due to pain; (3) Pain disturbs me if I walk more than 1 km; (4) Pain disturbs me during physical exercise class; and (5) Pain and aches disturb my hobbies. Use of painkillers was asked dichotomously (yes/no). 2.3. Statistical methods The descriptive variables are shown in frequencies, percentages, mean and SD. The 95% confidence intervals (CI) of probabilities were calculated with Clopper–Pearson method. The difference between groups among categorical variables was analysed by Pearson x2 test or Fisher – Freeman – Halton test. The linearity between pain and use of painkillers was calculated by the Cochrane –Armitage trend test. The association between pain frequency and intensity was analysed by analysis of variance. Spearman’s r was used for the nonparametric correlations. To apply the associations of neck pain and other variables, maximum-likelihood ordered logit estimation with forward stepwise procedure was used.
3. Results 3.1. Occurrence and changes of neck pain at the 1- and 4-year follow-ups At the 1-year follow-up, neck pain at least once a month was reported by 78 [21.3% (95% CI, 17.2– 25.9)] children, 45 [23.8% (18.3 –30.4)] girls and 33 [18.6% (13.6 –25.0)] boys ðP ¼ 0:23Þ: Neck pain at least once a week was reported by 23 [6.3% (95% CI, 4.0 –9.3]) children. At the 4-year follow-up, neck pain at least once a month was reported by 159 [43.4% (95% CI, 38.3 – 48.7)] children, 108 [57.1% (49.8 –64.3)] girls and 51 [28.8% (22.3 –36.1)] boys ðP , 0:001Þ: Neck pain at least once a week was reported by 71 [19.4% (95% CI, 15.5– 23.8)] adolescents. Fig. 1 shows the changes of neck pain from the baseline pain-free situation to the 1- and 4-year followups. Neck pain at least once a month was indicated in 115 (31.5%) earlier pain-free preadolescents at the 4-year follow-up. On the other hand, 34 out of 78 (43.6%) children who had neck pain at the 1-year follow-up became pain-free at the 4-year follow-up. Of those who
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3.2. Pain intensity and use of painkillers at the 4-year follow-up Mean (SD) intensity of pain was 36 (14) mm among those who reported neck pain once a week and 62 (27) mm among those who reported neck pain almost daily. The intensity of pain increased with the frequency of pain (P , 0:001 for linear trend). Of the adolescents with neck pain, 44 (28%) had used painkillers to relieve their pain. The proportion of painkiller users increased with the frequency of neck pain ðP ¼ 0:054Þ (Table 1).
Fig. 1. Occurrence and changes of neck pain among originally pain-free preadolescents at the 1- and 4-year follow-ups. Percentages in 1996 and 1999 refer to percentage of original 366 pain-free children. Open bar shows no neck pain, dotted neck pain once a month and black bar at least once a week.
Table 1 Intensity of pain and use of painkillers at the 4-year follow-up Descriptive variables
Neck pain frequency
P for linear trend
Once Once More than Almost a month a week once a week daily ðN ¼ 86Þ ðN ¼ 51Þ ðN ¼ 13Þ ðN ¼ 7Þ Pain intensity 25 (16) (VAS), mean (SD) Number of 19 (22) children having used pain killers (%) a b
36 (14)
55 (24)
62 (27)
17 (33)
5 (38)
3 (43)
3.3. Co-occurrence of other musculoskeletal pain with neck pain At the 1-year follow-up, neck pain at least once a month as a single musculoskeletal pain symptom had occurred in 28 children (7.6%), while the other 50 children (13.7%) reported neck pain combined with some other musculoskeletal pain (multiple pain). At the 4-year follow-up, neck pain at least once a month as a single pain had occurred in 35 (9.5%) children, while the other 124 (33.9%) reported multiple pain. Table 2 shows the co-occurrence of other musculoskeletal pain by neck pain frequency categories. In all neck pain frequency categories lower limb pain was the most common other musculoskeletal pain in both follow-ups.
,0.001a
3.4. Neck pain associated with headache and disability at the 4-year follow-up 0.054b
Analysis of variance (ANOVA). Cochran–Armitage trend test.
were pain-free at baseline, there were 44 (12.0%), who reported any neck pain at both follow-ups. Only seven (1.9%) children suffered from weekly neck pain at both follow-ups.
At the 4-year follow-up, headache at least once a month was reported by 238 (65.0%) and at least once a week by 91 (24.9%) adolescents. Only 14 (3.8%) adolescents had the highest subjective pain-induced disability index 3– 5/5 and 79 (21.6%) had disability index 1– 2/5. Most of the adolescents (74.6%) reported no disability. The frequency of neck pain correlated with the frequency of headache [r ¼ 0:39 (95% CI, 0.30 – 0.47)], and with disability [r ¼ 0:26 (95% CI, 0.16 – 0.35)].
Table 2 Co-occurrence of other musculoskeletal pain with neck pain in 1- and 4-year follow-ups
Upper limb Chest Lower limb Upper back Lower back Buttock
Neck pain frequency in 1-year follow-up, N (%)
Neck pain frequency in 4-year follow-up, N (%)
No pain ðN ¼ 280Þ
Once a month ðN ¼ 55Þ
At least once a week ðN ¼ 23Þ
No pain ðN ¼ 207Þ
Once a month ðN ¼ 88Þ
At least once a week ðN ¼ 71Þ
9 (3.1) 11 (3.8) 50 (17.4) 8 (2.8) 9 (3.1) 2 (0.7)
7 (12.7) 8 (14.5) 25 (45.6) 9 (16.4) 8 (14.5) 7 (12.7)
5 7 11 5 3 2
24 (11.6) 14 (6.8) 57 (27.5) 12 (5.8) 36 (17.4) 4 (1.9)
18 (20.5) 17 (19.3) 43 (48.9) 22 (25.0) 33 (37.5) 5 (5.7)
27 14 42 34 37 11
(21.7) (30.4) (47.8) (21.7) (13.0) (8.7)
(38.0) (19.7) (59.0) (47.9) (52.1) (15.5)
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3.5. The relationship between neck pain and other variables The relationship between neck pain and co-occurrence of other pains, age, gender, use of pain medication, headache and disability was explored by forward stepwise ordered logit estimation. The following variables entered into the model: upper back [OR ¼ 3.97 (95% CI, 2.72 –5.80)], headache [OR ¼ 1.75 (1.39 – 2.20)], girl [OR ¼ 2.76 (1.74 –4.37) and lower limb [OR ¼ 1.73 (1.33 – 2.26)].
4. Discussion To our knowledge the present study is the first prospective follow-up of pain-free preadolescents. We found that 21% of at the baseline pain-free preadolescents reported neck pain at the 1-year follow-up. Of those, who were still pain-free at the 1-year follow-up, 32% reported neck pain at the 4-year follow-up. In the recent adult study, 1-year cumulative incidence of neck pain was 18% (Croft et al., 2001). Feldman et al. (2002) found the cumulative annual incidence of neck pain at least once a week 10% among adolescents. In our study 6.3% had neck pain at least once a week at the 1-year follow-up. Of those, who were pain-free at the 1-year follow-up, 16% reported weekly neck pain at the 4-year follow-up. In our study the true annual cumulative incidence cannot be estimated, since we asked neck pain only during the preceding 3 months at the 1 and 4-year follow-up points, and it does not cover the whole follow-up time. Still our results are quite close to Feldman’s findings. The ‘1-year incidence’ was little less in our study, but can be explained by the difference in age group studied (our participants were preadolescents at the 1-year follow-up) and also by the fact that we asked symptoms during the preceeding 3 months not during the whole year. Hakala et al. (2002) published increasing prevalence rates in adolescents’ neck pain in the 1990s. Our study showed, however, that nearly half of the children with neck pain at the 1-year follow-up were pain-free at the 4-year follow-up. This indicates that neck pain symptoms fluctuate. Increasing prevalence rates in adolescence do not mean that symptoms persist among the same children. In this study, 12% reported neck pain at both follow-ups. Only 1.9% had symptoms at least once a week at both follow-ups. This is a group that probably would need a clinical attention already as preadolescents to prevent chronic pain and disability later in their lives. In preadolescence, no difference between genders was found in either the occurrence of neck pain, or in other musculoskeletal pain symptoms (Mikkelsson et al., 1997). In adolescence, however, neck pain was significantly more common among girls (13 – 16-year-olds). Similar results have been reported earlier in several studies of neck and low back pain (Balague´ et al., 1999; Hakala et al., 2002; Niemi et al., 1996; Smedbra˚ten et al., 1998; Vikat et al., 2000), further strengthening the evidence that girls are generally
more prone to any pain in adolescence. This suggests that some etiological factors might be related to sex-related hormonal changes and differences in musculoskeletal systems, while others might relate to differences in behavioural factors. The basic problem concerns, not only the underlying pathology and mechanism of pain, but factors influencing a subject’s response to symptoms. Boys might have a tendency to deny or girls to overestimate their symptoms at puberty. In order to determine frequency of pain episodes and severity of pain, a need for longitudinal studies has been noted (Bovim et al., 1994; McGrath, 1987). In this study, the intensity of pain was measured by VAS, and a linear association between the intensity and the frequency of neck pain was found. The pain intensity was low to moderate among those who reported neck pain once a week, but moderate to severe among those having symptoms more than once week. Thus, the frequency of pain reflected the intensity of pain fairly well. In this study, most adolescents with neck pain seemed to handle it without medication or significant disability, but a minority suffered from severe pain and used medication. The use of painkillers was associated with high pain frequency. We found that neck pain occurred more often with some other musculoskeletal pain than as a single pain. Co-occurrence of other musculoskeletal pain with neck pain indicates that some factors might be common to different musculoskeletal symptoms without specificity to neck pain. In fact, Mikkelsson et al. (1999) has earlier reported that 20% of children with neck pain at baseline reported widespread pain after 1-year follow-up. In our study, lower limb pain was the most common other pain with neck pain in both followups. Lower limb pain has earlier found to be the most common musculoskeletal pain among children and adolescents (Mikkelsson et al., 1997; Perquin et al., 2000; Roth-Isigkeit et al., 2003). Back pain co-occurred in half of the adolescents with neck pain at least once a week at the 4-year follow-up. The co-morbidity of neck and low back pain was found earlier in 12 –18-year-old Finnish school children (Vikat et al., 2000). Feldman et al. (2002) found that neck and upper back were the most common sites of pain in adolescents. In the 1990s, the new information and communication technology had a tremendous impact on adolescents’ everyday life. We may speculate that both static postures and static muscular activation patterns in computer using could explain partly this high co-occurrence between neck and back pain in adolescents. When we explored the relationship between neck pain and other variables in the study, we found that girls who have upper back pain, headache and limb pain are most likely to also have neck pain. The strength of this study is its fairly long follow-up. Also the fluctuation due to seasonal variation was precluded since the follow-ups were done at wintertime as at baseline (Feldman et al., 2002). Although the responding rate was quite good (71.9%), among the drop-outs, there were more
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boys than girls (91 vs. 52). We do not know the exact reasons for that and therefore, the impact on results is speculative. Another weakness of the study is that the disability questions were not specific for neck pain and may not describe the effects of neck pain on everyday life. In addition, we studied a defined subgroup of original sample and there are limitations in extrapolating the findings to the general literature. In summary, our results further strengthen the evidence that unspecific neck pain is common already in early adolescence, especially in girls, and even in subjects who had been asymptomatic in preadolescence. Factors contributing to this are unknown and further studies are needed to explore them. The co-occurrence of different musculoskeletal pain symptoms suggests that some determinants might be common to them. Although neck pain symptoms are common, they seem to fluctuate and minority represents chronic, persistent neck pain. However, good prognosis can be generalized only to this studied pain-free subgroup. Finally, our results indicate that in community studies the definition of neck pain by frequency also reflects the intensity of pain fairly well.
Acknowledgements We thank Mrs Tuija Sulonen, RN, for assistance in collecting the data at follow-up. Funding. This study was supported by Signe and Ane Gyllenberg’s Foundation, by the Medical Research Fund of the Rheumatism Foundation Hospital, the University Hospital of Turku and Jyva¨skyla¨ Central Hospital.
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