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Association of age and physical job demands with musculoskeletal disorders in nurses
Applied Ergonomics 44 (2013) 652e658
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Association of age and physical job demands with musculoskeletal disorders in nurses Barbara Heiden a, *, Matthias Weigl a, Peter Angerer b, Andreas Müller b a b
Institute and Outpatient Clinic for Occupational, Social and Environmental Medicine, Ludwig-Maximilians-University Munich, Ziemssenstr. 1, 80336 Munich, Germany Institute for Occupational Medicine and Social Medicine, Medical Faculty, Düsseldorf University, Universitätsstr. 1, 40225 Düsseldorf, Germany
a r t i c l e i n f o
a b s t r a c t
Article history: Received 27 May 2011 Accepted 2 January 2013
A cross-sectional study design was applied on 273 nurses to investigate associations of physical job demands, age, and musculoskeletal disorders (MSDs) in nursing. Concurrently, participants reported on various physical job demands with a standardized questionnaire for Hospital Work. As a special contribution, this investigation illustrates findings on MSDs provided by a standardized physical examination to questionnaire data. MSD located in the lower back (8.7%) had the highest frequency, followed by the neck (7.3%), the shoulders (6.9%), and the knees (2.2%). There were significant differences in the frequencies of MSD between the young/middle age-group and the old age-group in most locations, while the only significant difference between the young and the middle age-group was found for shoulderMSD. Furthermore high levels of physical job demands increased the risk of MSD significantly (OR ¼ 5.7, 1.55e20.96) in all age-groups. The study provides further indication for development of ageadapted preventive measures. Ó 2013 Elsevier Ltd and The Ergonomics Society. All rights reserved.
Keywords: Musculoskeletal disorders Physical job demands Nursing
1. Introduction To tackle the contemporary issues brought by an aging health care workforce in Western countries and in order to master the expected increasing demand in delivery of care (Giannakouris, 2010; Simeons et al., 2005), health care organizations face the distinctive challenge to maintain the well-being of nurses over a whole working life (Camerino et al., 2006; Simon et al., 2008, 2010). In consequence, age-appropriate work design will be of special interest over the coming years. It seems generally acknowledged that nurses have an increased risk of musculoskeletal disorders (MSDs). Most frequently reported MSDs are low back pain, followed by neck and shoulder problems, and knee pain (Ando et al., 2000; Chiou et al., 1994; Engels et al., 1996; Lagerstrom et al., 1995; Lusted et al., 1996; Maul et al., 2003; Menzel et al., 2004; Smedley et al., 2003; Smith et al., 2003b; Trinkoff et al., 2002). Furthermore, MSDs are an important factor in the nurses’ consideration to change jobs or even to leave the nursing profession (Blekesaune and Solem, 2005; Fochsen et al., 2006). Physical capabilities (such as muscle mass and therefore muscular strength) that enable people to cope with physical job demands naturally undergo an age-related decline over time (Voorbij and Steenbekkers, 2001). Thus, an increased risk of MSD for elderly * Corresponding author. Tel.: þ49 89 5160 5302; fax: þ49 89 5160 5306. E-mail address: [email protected] (B. Heiden).
nurses seems plausible, because throughout a working life there could be a growing discrepancy between individual’s physical capabilities and physical job demands. Some studies confirm such an association between the age of nurses and MSDs (predominantly neck, arms, lower back) (Alexopoulos et al., 2003; Engels et al., 1996; Lagerstrom et al., 1995; Larusso et al., 2007; Leighton and Reilly, 1995; Trinkoff et al., 2003); nevertheless, others disagree with those findings (Ando et al., 2000; Daraiseh et al., 2003, 2010; Menzel, 2004). Da Costa and Vieira (2010) published a review about longitudinal and cohortstudies which investigated risk factors for work-related musculoskeletal disorders e including age. Only two of those studies were related to nursing (Venning et al., 1987; Smedley et al., 2003): Smedely et al. demonstrated a weak but not significant association of neck and shoulder pain with the increasing age of nurses. Venning et al. did not find any association between back pain and age of nurses. A potential “healthy worker effect” might interfere with most age-related results (Li and Sung, 1999), such as severely ill and disabled nurses might have left the profession prematurely or changed to jobs with less exposure to physical demands. This might be an explanation for the absence of a (expected) positive age effect. Thus, findings from existing studies illustrating the relation between the age of nurses and MSDs are inconsistent. Considering these results, it must be taken into account that those studies usually have a cross-sectional design, and therefore no causal
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B. Heiden et al. / Applied Ergonomics 44 (2013) 652e658
relation can be drawn. Moreover, age is often removed or adjusted in the analysis when MSDs are studied. Thus, more research might be helpful to clarify the relation of nurses’ age and MSDs, especially concerning different age-groups as such differences could be relevant for preventive measures. Studies also indicate that physical job demands common in nursing are associated with an increased risk of MSD: frequent lifting of heavy loads, patient transfers, extreme flexion, bending, twisting and sudden movements in non-neutral positions increase the risk of back complaints and back injuries (Engkvist et al., 1998; Hoogendoorn et al., 2000; Lipscomb et al., 2011; Long et al., 2012; Punnett and Wegman, 2004; Trinkoff et al., 2001). Lifting and bending were shown to be associated with arm and neck complaints (Engels et al., 1996). Working with arms and hands in awkward positions and repetitive motions with hands/wrists are associated with pain in hands, arms and shoulder (Punnett et al., 2000; Trinkoff et al., 2003). However, study results about MSDs and the association with physical job demands in nursing are almost exclusively based on self-reports. Therefore, observed relationship might be over- or underestimated due to common method bias (Podsakoff et al., 2003). A systematic bias of study results consequently can lead to suboptimal conclusions for effective measures to prevent MSDs (Trinkoff et al., 2003). Research efforts using more objective measures to assess MSDs in nursing, e.g. a physical examination for health effect and/or workplace observations for health risks, are rare. Knibbe and Friele (1999) and Warming et al. (2009) tried to overcome the shortcomings of questionnaire data to assess health risks (physical job demands) by logbooks-registration. They showed an association of nursing tasks and MSDs. The present study aims to overcome some shortcomings of selfreporting questionnaires in the documentation of health effects. We applied an expert-based, standardized physical examination to assess MSDs. Drawing on a sample of nurses in inpatient care, we sought to address the following questions: - Are there differences between three age-groups (<35, 35e44, 45 years) concerning the frequency of MSDs? - Are there age-dependent differences in the location of MSDs? - Are physical job demands in nursing related to MSDs? - Does the strength of the relation between physical job demands and MSDs differ between three age-groups?
2. Methods and material 2.1. Design Data were gathered in a cross-sectional study design among hospital nurses working in a University Hospital in Southern Germany by means of a physical examination and a self-reporting questionnaire. To allow matching of the questionnaire data with the data of the physical examination, pseudonymisation was carried out by assigning a five-digit code. Participation in any part of the investigation was voluntary and the voluntary time counted as working time. The study was approved by the Ethics Committee of the Faculty of Medicine, Munich University. 2.2. Sample 952 nursing professionals were invited in writing to take part in the survey and the physical examination. The nursing units were selected by the nursing management: all intensive care units, all operation units, all anesthesia units, three general inpatient wards and the unit for patient transfers were selected; leading to an
653
overrepresentation of critical care nurses and an underrepresentation of nurses from general inpatient wards in the sample. 2.3. Procedure The nursing professionals were informed in advance about the objective and the procedure of the project. The questionnaire and the consent forms (survey and physical examination) were sent together with the invitation. Those who decided to take part in the survey and/or the physical examination had to send back the written informed consent. Participation in any part of the investigation was independent from one another (Table 1). The deadline for returning the questionnaire was two weeks after the invitation date. The return was anonymous. An appointment with the physician was made with those participants who had sent back their written informed consent to the physical examination. The examination was divided into a detailed structured interview and a systematic orthopedic screening examination of all body sites. 2.4. Measures Musculoskeletal disorders (MSD) were assessed with a screening examination suggested by Spallek et al. (fokusÓ) which was based on widely accepted clinical tests summarized in Table 2 (Spallek et al., 2007). The examination focuses on musculoskeletal impairment, restriction of mobility, and pain, which are the most relevant symptoms of MSD in occupational contexts. It is recommended by the German Federal Institute for Occupational Safety and Health (FIOSH, BAuA) as a systematic orthopedic examination under occupational conditions. This recommendation is given associated with the national implementation of the EU manual handling directive (90/269/EEC) for the public services in Germany (Steinberg et al., 2006). Results were documented on the basis of the neutral-zeromethod and comparing both corporal sides. The neutral-zeromethod assesses the mobility of joints in angular degrees as the maximum deflection from a defined, neutral starting position (0 ). All examinations were carried out by one specially trained physician applying uniform diagnostic criteria. Further, data about prevention of activity in the preceding 12 months due to musculoskeletal problems at the neck, shoulders, elbows, hands, lower back, knees and feet/ankles were obtained via questionnaire, measured as a yes/no item for each body site [“During the last 12 months have you been prevented from carrying out normal activities (e.g. job, housework, hobbies) because of this trouble?”]. Work- and not-work-related accidents were assessed for each of the examined body site by the doctor during the interview, e.g.: “Did you ever have an accident that caused a shoulder injury?” (0 ¼ “no”, 1 ¼ “yes”). If “yes”: “Was it an occupational injury?” (0 ¼ “no”, 1 ¼ “yes”).
Table 1 Consent to the participation in the survey and/or the physical examination (N ¼ 953). Survey
Physical examination
Yes No
Yes
No
264 (27.7%) 165 (17.3%)
9 (0.9%) 515 (54.0%)
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B. Heiden et al. / Applied Ergonomics 44 (2013) 652e658
Table 2 Orthopedic screening examination by Spallek et al. e criteria for positive findings. Body site and test
Cervical spine Rotation in neutral position Lateral bending Extension/flexion Thoracic/Lumbar spine Flexion: distance of fingers from floor Lateral flexion Lateral rotation Pain on percussion /pressure Standing/Walking on toes and heels
Balancing on one leg
Standing up from squat
Shoulder/Arm Abduction, external rotation: thumb on the back of the neck, pointing downwards Adduction, internal rotation: hand behind the back (like tying an apron), thumb upwards Abduction: place the hand on the opposite shoulder Arm/Hand Actively gripping and lifting a chair in pronation and supination
Criteria for positive finding Right
Left
<70
<70
<45 <45
<45 <45
>15 cm <30 <30 Yes
<30 <30
Impossibility Weakness Difference to left side >6 s Impossibility Weakness Impossibility Weakness of the hip/thigh Difference to left side
Impossibility Weakness Difference to right side >6 s Impossibility Weakness Impossibility Weakness of the hip/thigh Difference to right side
tool (Büssing and Glaser, 2000; Weigl et al., 2010). Participants were asked to rate the degree, to which their work requires them to lift heavy loads with two items (“In this job one consistently has to lift heavy patients” and “. to lift heavy objects.”). Uncomfortable body postures were evaluated with four items (“In this job one consistently has to lift objects far from the body.”, “. to work in standing position for several hours a day.”, “. to bend several times every hour.“, “.to maintain uncomfortable working positions.”). Items used a 5-point Likert scale ranging from 1 ¼ “not at all” to 5 ¼ “to a very great extent”. Internal consistency (Cronbach’s alpha) of the scale was 0.83. The overall scale was categorised as low (scale mean <2.5), moderate (2.5e3.5), and high (>3.5) physical job demands. The lowest category served as a reference category in the regression analyses. Demographic variables were age, gender (0 ¼ male, 1 ¼ female), and years in nursing, which were collected via questionnaire. Confounding variables were exercise, smoking and body mass index (BMI). Exercise was measured as a single item: “How often are you doing physical activities for at least 20 min that make you at least sweat a little bit or be short of breath (e.g., sports, hiking, dancing)?” The Item used a 5-point scale ranging from 1 ¼ “daily” to 5 ¼ ”never”. Smoking was assessed with one question: “Do you smoke?” (0 ¼ “no”, 1 ¼ “yes”). BMI was calculated according to the formula BMI ¼ m/l2 (m ¼ body weight in kg, l ¼ body height in m). Exercise and BMI were included as continuous variables into the analysis.
>0 cm difference between right and left side
2.5. Data analyses >2 cm difference between right and left side
Difference between right and left side
Impossibility Impossibility Weakness Weakness Difference to left side Difference to right side
Knee/Ankle Squatting as low as possible with heels on the floor and subsequently standing up slowly Balancing on one leg
Weakness of the foot Weakness of Difference to left side the foot Difference to right side <6 s <6 s Difference to left side Difference to right side Hopping on one leg Impossibility Impossibility Weakness of the foot Weakness of the Difference to left side foot Difference to right side Walking on toes and heels Impossibility Impossibility Weakness of the foot Weakness of the foot Difference to left side Difference to right side Standing on feet’s outer edges Impossibility Impossibility Difference to left side Difference to right side
Accordingly, the operational case definition of an MSD at a specific body site in this study was based on the following criteria: (i) a positive result in one of the relevant tests for this body site (Table 2) or manifestation of pain during the examination maneuvers, and (ii) prevention of activities (work, household, leisure) by musculoskeletal problems at the same body site in the preceding 12 months, and (iii) no not-work-related accident at the relevant body site in the past. Physical job demands and uncomfortable body postures were assessed with a total of 10 items. Physical job demands were assessed with a German six-item scale of the hospital work analysis
Data was entered twice in a common spreadsheet program. Consistency, logic and range checks of the data were carried out. SPSS 19.0 was used for statistical analyses. To perform further analyses, age was categorized into three groups: <35, 35e44 and 45 years. To investigate the differences between the three age-groups regarding the prevalence of MSDs, Chi-square-tests were used. The odds of observed MSDs were analyzed in respect to the overall physical job demands scale with multivariate hierarchical logistic regressions. In the first step of the regression, analysis the sociodemographic (age, gender, years in nursing) and confounding variables (exercise, smoking, BMI) were included in the model. In the second step incremental effects of physical job demands were tested. Beside an analysis of the total sample, we computed separate regression models of three agegroups to test for age-specific effects of physical job demands in nursing on MSDs. To account for multi-collinearity, all continuous predictor variables were mean centered (Aiken and West, 1991). 3. Results 3.1. Demographic, employment, and health behaviour characteristics The 273 nursing professionals who took part in the physical examination did not differ from the total sample of participating nurses (Table 3) regarding gender, but were older: 39.3 years (standard deviation, SD ¼ 11.7) in the physical examination group, 38.5 years (SD ¼ 11.3) in the total sample (T ¼ 1.94, p ¼ 0.053). Participants’ age ranged from 21 to 63 in both groups. Additionally, nurses who took part in the physical examination had more years in the nursing profession (19.1 years/SD ¼ 11.7; total sample: 18.2 years/SD ¼ 11.0; T ¼ 2.4, p ¼ 0.015). 136 (49.8%) nurses were from intensive care units (pediatric and adult), 58 (21.2%) from the operating theatre (pediatric and adult), 41 (15.0%) from anesthesia wards or units (pediatric and adult) and 34 (12.5%) from general inpatient wards. 4 (1.5%) male nurses were from the unit responsible for patient transfers in the operating
B. Heiden et al. / Applied Ergonomics 44 (2013) 652e658 Table 3 Descriptive statistics of the participants in the physical examination.
Age Stature Weight BMI Years in nursing Years in this hospital Years in current job position Fitness
Mean (SD)
Range
39.31 (11.65) years 1.69 (0.08) m 70.77 (14.65) kg 24.85 (4.6) kg/m2 19.11 (11.66) 12.69 (9.46) 10.07 (8.68) 1e2 per week
21e63 years 1.50e1.92 m 45e137 kg 16e46 kg/m2 2e45 0e42 0e35 Never to daily
655
shoulders (6.9%), and knees (2.2%). Feet/ankles and elbows/hands were least affected (1.5%; 1.1%). In 21 (7.7%) of the participants MSDs were detected at more than one body site, in 5 (1.8%) at more than two, and in 3 (1.1%) at more than three body sites. 22 (8.1%) participants had an accident with an injury of the neck in the past, 16 (5.9%) of the shoulders and 9 (3.3%) of the lower back e none of them was work-related. 68 (25%) participants reported an accident with an injury of the feet/ankles, 60 (22%) of the elbows/ hands and 49 (18%) of the knees e one of each was work-related.
Number (%)
3.3. Age and MSD
Gender Female Male Age-groups <35 years 35e44 years 45 years Unit/Ward Intensive care Anesthesiology Operating room General ward Patient positioning Full-time Part-time Smoker Non-smoker
232 (85.0%) 41 (15.0%) 112 (41.0%) 63 (23.1%) 98 (35.9%) 136 41 58 34 4 201 66 69 204
(49.8%) (15.0%) (21.2%) (12.5%) (1.5%) (75.3%) (24.7%) (25.1%) (74.2%)
rooms. 232 (85.0%) nurses were female and 41 male (15.0%). Considering three age-groups, 112 nurses were <35 years (41.0%), 63 between 35 and 44 years (23.1%) and 98 45 years (35.9%). The nurses had an average BMI of 24.85 kg/m2 (SD ¼ 4.6). Most of them reported exercising once or twice a week (corresponding to a mode of 3). 69 (25.1%) nurses were smokers. 3.2. Prevalence of MSDs, based on results of a physical examination 47 (17.2%) participants showed MSDs according to our case definition at one body site at least. Women were more often affected than men (17.7% vs. 14.6%), but the difference was not significant [c2 (df ¼ 1, N ¼ 273) ¼ 0.226, p ¼ 0.635]. Participants with a positive result at a specific body site in the physical examination also reported prevention of activity because of complaints at that body site in 32.3% (neck) to 75.0% (feet). In contrast 77.6% (lower back) to 93.9% (feet/ankles) of those participants with a negative physical examination result also did not report any complaints at that body site. In general, self-reported complaints and results of the physical examination at a specific body site were in accordance, but varying from 67.5% (lower back) to 93.3% (feet/ankles). According to the operational case definition (Table 4), MSDs of the lower back (8.7%) were most frequent, followed by neck (7.3%),
The frequency of having at least one MSD significantly increased with age, c2 (df ¼ 2, N ¼ 273) ¼ 28.27, p ¼ 0.000. There is no significant increase of MSDs from the young (<35 years) to the middle (35e44 years) age-group, but from the young to the old age-group (45 years), [c2 (df ¼ 1, N ¼ 208) ¼ 25.68, p ¼ 0.000], and also from the middle to the old age-group [c2 (df ¼ 1, N ¼ 161) ¼ 8.18, p ¼ 0.004]. The three age-groups also differ significantly regarding the frequency of MSD at different body sites, showing a significant increase from the young to the old age-group for neck, shoulders and lower back (Table 5). Comparing the young and the middle agegroup, there is only a significant higher frequency of shoulder-MSD in the middle age-group. Comparing the middle and old age-group, there is a significant higher frequency of neck- and lower back-MSD in the older nurses. Although there are more knee-MSD-cases in the old age-group than in the young and middle age-group, this difference is not significant. 3.4. Physical job demands and MSDs The levels of reported physical job demands were comparable in all age-groups [c2 (df ¼ 2, N ¼ 273) ¼ 1.72, p ¼ 0.422]. High levels of reported physical job demands are significantly related with the risk of MSDs (indicated by odds, Table 6). The risk increases for high levels, but not for moderate levels of physical job demands relative to the reference category of low physical job demands. The effects of high levels of physical job demands exist over and above the effects of sociodemographic variables, health related behaviour (exercise, smoking) and body mass. Physical job demands are related with the increased risk of MSDs in nurses of the middle age-group, but not in the young and the old age-group (Table 7). 4. Discussion Objectivity in diagnosing MSDs is difficult to achieve as complaints may arise without any physical findings and physical findings may remain without complaints. So neither physical examination nor self-reporting questionnaires are reliable
Table 4 Number of participants per criterion of case definition, number of accidents and final number of cases.
Positive result in the physical examinationa Prevention of activities in the preceding 12 monthb Positive result in the physical examination plus prevention of activities in the preceding 12 month Accidents in the past Work-related Not-work-related a b
Neck (n ¼ 260)
Shoulders (n ¼ 256)
Elbows/Forearms/ Hands (n ¼ 255)
Lower back (n ¼ 259)
Knees (n ¼ 254)
Feet/Ankles (n ¼ 252)
65 (25.0%) 44 (16.9%) 21 (8.1%)
44 (17.2%) 35 (13.7%) 17 (6.6%)
11 (4.3%) 27 (10.7%) 6 (2.4%)
67 (25.9%) 69 (26.6%) 26 (10.0%)
28 (11.0%) 32 (12.6%) 12 (4.7%)
8 (3.2%) 21 (8.3%) 6 (2.4%)
0 22
0 16
1 60
0 9
1 49
1 68
Positive result in one of the relevant tests for the body site or manifestation of pain during the examination maneuvers. Prevention of activities (work, household, leisure) by musculoskeletal problems at the body site in the preceding 12 months.
656
B. Heiden et al. / Applied Ergonomics 44 (2013) 652e658
Table 5 Frequency of musculoskeletal disorders (MSD) by location and age-group. MSD
Age-groups (in years) 35 (a)
35e44 (b)
45 (c)
c2 (df)
p-value
Compared age-groups
Neck Yes No
0.9% (n ¼ 1) 99.1% (n ¼ 109)
4.8% (n ¼ 3) 95.2% (n ¼ 60)
15.3% (n ¼ 15) 84.7% (n ¼ 83)
2.633 4.294 15.129
0.105 0.038 0.000
ab bc ac
Shoulder Yes No
0.9% (n ¼ 1) 99.1% (n ¼ 110)
7.9% (n ¼ 5) 92.1% (n ¼ 58)
12.2% (n ¼ 12) 87.8% (n ¼ 86)
5.975 0.754 11.482
0.015 0.385 0.001
ab bc ac
Elbows/Forearms/Hands Yes 0.0% (n ¼ 0) No 100% (n ¼ 110)
1.6% (n ¼ 1) 98.4% (n ¼ 61)
2.0% (n ¼ 2) 98.0% (n ¼ 96)
1.785 0.38 2.267
0.182 0.846 0.132
ab bc ac
Lower back Yes No
2.7% (n ¼ 3) 97.3% (n ¼ 109)
3.2% (n ¼ 2) 96.8% (n ¼ 61)
19.4% (n ¼ 19) 80.6% (n ¼ 79)
0.036 8.888 15.559
0.850 0.003 0.000
ab bc ac
Knees Yes No
0.9% (n ¼ 1) 99.1% (n ¼ 109)
0.0% (n ¼ 0) 100% (n ¼ 63)
5.2% (n ¼ 5) 94.8% (n ¼ 92)
0.576 3.352 3.301
0.448 0.067 0.069
ab bc ac
Feet/Ankles Yes No
0.0% (n ¼ 0) 100% (n ¼ 112)
1.6% (n ¼ 1) 98.4% (n ¼ 62)
3.1% (n ¼ 3) 96.9% (n ¼ 95)
1.788 0.344 3.478
0.181 0.558 0.062
ab bc ac
Total Yes No
5.5% (n ¼ 6) 94.5% (n ¼ 104)
12.7% (n ¼ 8) 87.3% (n ¼ 55)
32.7% (n ¼ 32) 67.3% (n ¼ 66)
2.826 8.178 25.677
0.093 0.004 0.000
ab bc ac
instruments by themselves. This cross-sectional study addresses the effects of physical job demands and age in terms of MSDs in nurses by assessing both, physical findings and complaints. Studies that assess MSDs in nursing by integrating a physical examination are rare. Most studies are exclusively based on self-reporting questionnaires to assess both e exposures and health effects. So this investigation tries to overcome an important shortcoming in the field of health effects. The MSD most frequently observed was located in the lower back, followed by neck/shoulders, and knees. This ranking of location matches with existing study results assessed by selfreports, but relative frequencies in our study were much lower (Ando et al., 2000; Daraiseh et al., 2010; Engels et al., 1996; Smith et al., 2003a; Trinkoff et al., 2003). One reason for this rather low frequency may be due to the restrictive case definition and Table 6 Adjusted odds ratio of musculoskeletal disorders in nurses by level of reported physical job demands, sociodemographic variables, health related behaviour, and body mass (N ¼ 273). Variable
Musculoskeletal disorders (MSD) OR (95% CI)
Age (continued) Gender Male Female Years in profession (continued) Exercise (continued) Smoking No Yes Body mass index (continued) Physical job demands Low (mean <2.5) (n ¼ 42) Moderate (mean 2.5e3.5) (n ¼ 123) High (mean >3.5) (n ¼ 98)
3.68 (1.11e12.18)
Notes. OR: odds ratio; CI: confidence interval.
1.00 1.77 (0.55e5.75) 0.87 (0.30e2.57) 1.11 (0.74e1.67) 1.00 0.84 (0.33e2.17) 0.92 (0.68e1.23) 1.00 2.63 (0.71e9.67) 5.70 (1.55e20.96)
multi-method assessment of MSDs. It is possible that especially the criterion “prevention of activities” resulted in a selection of rather serious cases and therefore smaller numbers. However, comparisons between studies must be handled with care as the methods used to assess MSDs as well as the case definitions do not completely correspond (Punnett and Wegman, 2004). Our study provides further information to the evidence base of age effects on MSDs in nursing professionals (Ando et al., 2000; Da Costa and Vieira, 2010; Engels et al., 1996; Lagerstrom et al., 1995; Leighton and Reilly, 1995; Menzel, 2004; Venning et al., 1987). Our data support an association of age and MSDs in nursing professionals, with a general increase up to the oldest age-group (45 years). MSDs in this age-group were mainly located in the back, neck and shoulders. A noticeable result is significant increase of most MSDs from the middle to the old age-group, but only one significant difference e in shoulder-MSDs e between the young and the middle age-group. There seems to be an earlier onset of shoulder-MSDs. Considering the most frequent locations of MSDs in the three age-groups e middle and old age-group: shoulder; Table 7 Age specific adjusted odds ratios of musculoskeletal disorders (MSD) by level of reported physical job demands in nurses. Physical job demands by age-groups Nurses <35 years (n ¼ 106) Low and moderate (mean 1e3.5) (n ¼ 63, 59%) High (mean >3.5) (n ¼ 43, 41%) Nurses 35e44 years (n ¼ 62) Low and moderate (mean 1e3.5) (n ¼ 43, 69%) High (mean >3.5) (n ¼ 19, 31%) Nurses 45 years (n ¼ 95) Low and moderate (mean 1e3.5) (n ¼ 59, 62%) High (mean >3.5) (n ¼ 36, 38%)
Musculoskeletal disorders (MSD) OR (95% CI) 1.00 1.23 (0.18e8.49) 1.00 10.31 (1.46e72.81) 1.00 2.09 (0.81e5.42)
Notes. Models are adjusted by gender, years in profession, exercise, smoking behaviour, body mass index, OR: odds ratio; CI: confidence interval.
B. Heiden et al. / Applied Ergonomics 44 (2013) 652e658
young age-group: lower back e our results agree with the review of Da Costa and Vieira (2010). It showed some evidence for older age nurses being exposed to a risk factor for neck- and shoulder-MSDs. For MSDs of the lower back, younger age nurses appear to be exposed to a risk factor. It is remarkable that the steep increase in MSDs that we found in older nurses exists despite a potential “healthy worker effect”. One might speculate that nurses who are severely affected by MSDs change their job or take early retirement. In consequence, the actual number of nurses with MSDs and therefore the risk of older nurses to suffer MSD may be greatly underestimated in our study. More alarmingly are our findings in nurses >45 years, which show a higher prevalence of MSDs in comparison to both other agegroups. Furthermore, our study provides evidence that high physical job demands in nursing are related to MSDs. As expected, and documented by other studies (Harcombe et al., 2010, 2009; Josephson et al., 1997; Trinkoff et al., 2003), a general association between MSDs and physical job demands was evident, but some details were contradicting. Trinkoff et al. (2002) for example observed an increased risk of MSD for moderate and high physical job demands. In the present study, only physical job demands at high levels were associated with an increased risk of MSDs. This discrepancy may be explained by common method variance as Trinkoff et al. (2003) assessed data exclusively by self-report (Podsakoff et al., 2003). But also differences in the methods, e.g. grading of physical job demands, wording of the questions and/or differences in case definitions for MSDs must be taken into account (Punnett and Wegman, 2004). Considering the three age-groups there was only a significant association between physical job demands and MSDs in the middle age-group, but not in the youngest nor the oldest age-group. These differences between the age-groups may indicate that the years between the age of 35 and 44 are a special vulnerable phase for nurses to develop MSDs due to physical job demands in nursing, corresponding to the theory of “premature physiological aging“ of the muscular skeletal system (Barbini and Squadroni, 2003.). High physical demands in nursing, e.g. physical patient handling, may cause overload to the musculoskeletal system, with the effect of a “cumulative trauma”, and thus may result in a premature degenerative process (Kumar, 2001; Menzel et al., 2004). Nevertheless, it is important to keep in mind that the number of cases was quite low. Also it was a cross-sectional study and therefore no causal relation can be drawn. Our study has several limitations: even though this study aimed to overcome the predominance of questionnaire data in research on MSD in nursing, data on physical job demands are still based on self-reports. Thus, objectivity of this information might be questioned. However, a validation study on the used instrument demonstrated a high convergence between job incumbents’ ratings and external observations (Büssing and Glaser, 2002). Nevertheless, efforts should be made in future studies to obtain further information on physical job demands with additional instruments, e.g. structured observations. Because of non-probability, the low participation rate and the small sub-group consent to the physical examination potential sample selection bias may affect the external validity, and thus representativeness of our findings. However, we expect only minor effects of sample selection bias on our study results for the following reasons: we performed a post hoc analysis which revealed that our study sample and nurses who decided not to participate in the physical examination did not differ in physical health status as measured with the SF-12 questionnaire (Ware et al., 1996). Moreover, despite the underrepresentation of nurses working in general inpatient wards, our study sample is similar to the typical
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German workforce in nursing regarding age, gender structure and years in nursing (Isfort and Weidner, 2010). Therefore, it seems plausible that our findings may be replicable in other nursing settings. Information bias cannot completely be ruled out, especially as the nurses had to be informed in advance about the study objectives. We used the following measures to minimize information bias in our study: we avoided the main cause of information bias by gathering the information from all participants in the same way (Grimes and Schulz, 2002). As the physician did not know the survey results on physical stressors at the time of the examination we could also exclude diagnostic suspicion bias, i.e. caused by a more intensive search for MSDs due to positive results about exposure in the questionnaire (Grimes and Schulz, 2002). Moreover, it is impossible that the results of the physical examination influenced nurses’ response behaviour on physical work stressors as the survey took place before the physical examination. Finally, the representativeness of the observed age effects may be restricted to the three age-groups of our study. We used this specific definition of age-groups for the following reasons: nurses remain on average a rather short time in their profession (10- to 15year), so the group <35 years was considered separately as nurses may have already left the nursing profession around this time period. Nurses 45 years were chosen as the third group because there is evidence that they report considerable reduced work ability at this age (Camerino et al., 2006; Hasselhorn et al., 2003). However, further research may replicate our findings using a different definition of age-groups. 5. Conclusions The interaction between the age of nurses, their physical work demands, and the risk and location of MSD seems to be complex and multifaceted. Our study shows that older nurses have to suffer an increased risk of MSD. At the same time, the study indicates that even the youngest age-group suffers from MSD. Finally, we observed that physical job demands in nursing are a risk factor for MSD especially in the middle age-group. Thus, in terms of the design of adequate interventions for health promotion, our study’s results emphasize the importance of an early onset of prevention activities regarding MSDs and their extension over the whole working life. According to our results, age-specific priorities in prevention activities should be reconsidered. As the causes for MSDs are multi-factorial a wide range of detrimental working conditions should be optimized and redesigned. Ethics Approval to conduct the research study related to this paper was obtained from the Ethics Committee of the Faculty of Medicine, Munich University (No 256-09). Funding This study was supported by a grant from the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG): MU 3079/11 and the Munich Center of Health Sciences. The project is part of the DFG priority program 1184 “Age-differentiated work systems”. Competing interests None.
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Applied Ergonomics journal homepage: www.elsevier.com/locate/apergo
Association of age and physical job demands with musculoskeletal disorders in nurses Barbara Heiden a, *, Matthias Weigl a, Peter Angerer b, Andreas Müller b a b
Institute and Outpatient Clinic for Occupational, Social and Environmental Medicine, Ludwig-Maximilians-University Munich, Ziemssenstr. 1, 80336 Munich, Germany Institute for Occupational Medicine and Social Medicine, Medical Faculty, Düsseldorf University, Universitätsstr. 1, 40225 Düsseldorf, Germany
a r t i c l e i n f o
a b s t r a c t
Article history: Received 27 May 2011 Accepted 2 January 2013
A cross-sectional study design was applied on 273 nurses to investigate associations of physical job demands, age, and musculoskeletal disorders (MSDs) in nursing. Concurrently, participants reported on various physical job demands with a standardized questionnaire for Hospital Work. As a special contribution, this investigation illustrates findings on MSDs provided by a standardized physical examination to questionnaire data. MSD located in the lower back (8.7%) had the highest frequency, followed by the neck (7.3%), the shoulders (6.9%), and the knees (2.2%). There were significant differences in the frequencies of MSD between the young/middle age-group and the old age-group in most locations, while the only significant difference between the young and the middle age-group was found for shoulderMSD. Furthermore high levels of physical job demands increased the risk of MSD significantly (OR ¼ 5.7, 1.55e20.96) in all age-groups. The study provides further indication for development of ageadapted preventive measures. Ó 2013 Elsevier Ltd and The Ergonomics Society. All rights reserved.
Keywords: Musculoskeletal disorders Physical job demands Nursing
1. Introduction To tackle the contemporary issues brought by an aging health care workforce in Western countries and in order to master the expected increasing demand in delivery of care (Giannakouris, 2010; Simeons et al., 2005), health care organizations face the distinctive challenge to maintain the well-being of nurses over a whole working life (Camerino et al., 2006; Simon et al., 2008, 2010). In consequence, age-appropriate work design will be of special interest over the coming years. It seems generally acknowledged that nurses have an increased risk of musculoskeletal disorders (MSDs). Most frequently reported MSDs are low back pain, followed by neck and shoulder problems, and knee pain (Ando et al., 2000; Chiou et al., 1994; Engels et al., 1996; Lagerstrom et al., 1995; Lusted et al., 1996; Maul et al., 2003; Menzel et al., 2004; Smedley et al., 2003; Smith et al., 2003b; Trinkoff et al., 2002). Furthermore, MSDs are an important factor in the nurses’ consideration to change jobs or even to leave the nursing profession (Blekesaune and Solem, 2005; Fochsen et al., 2006). Physical capabilities (such as muscle mass and therefore muscular strength) that enable people to cope with physical job demands naturally undergo an age-related decline over time (Voorbij and Steenbekkers, 2001). Thus, an increased risk of MSD for elderly * Corresponding author. Tel.: þ49 89 5160 5302; fax: þ49 89 5160 5306. E-mail address: [email protected] (B. Heiden).
nurses seems plausible, because throughout a working life there could be a growing discrepancy between individual’s physical capabilities and physical job demands. Some studies confirm such an association between the age of nurses and MSDs (predominantly neck, arms, lower back) (Alexopoulos et al., 2003; Engels et al., 1996; Lagerstrom et al., 1995; Larusso et al., 2007; Leighton and Reilly, 1995; Trinkoff et al., 2003); nevertheless, others disagree with those findings (Ando et al., 2000; Daraiseh et al., 2003, 2010; Menzel, 2004). Da Costa and Vieira (2010) published a review about longitudinal and cohortstudies which investigated risk factors for work-related musculoskeletal disorders e including age. Only two of those studies were related to nursing (Venning et al., 1987; Smedley et al., 2003): Smedely et al. demonstrated a weak but not significant association of neck and shoulder pain with the increasing age of nurses. Venning et al. did not find any association between back pain and age of nurses. A potential “healthy worker effect” might interfere with most age-related results (Li and Sung, 1999), such as severely ill and disabled nurses might have left the profession prematurely or changed to jobs with less exposure to physical demands. This might be an explanation for the absence of a (expected) positive age effect. Thus, findings from existing studies illustrating the relation between the age of nurses and MSDs are inconsistent. Considering these results, it must be taken into account that those studies usually have a cross-sectional design, and therefore no causal
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B. Heiden et al. / Applied Ergonomics 44 (2013) 652e658
relation can be drawn. Moreover, age is often removed or adjusted in the analysis when MSDs are studied. Thus, more research might be helpful to clarify the relation of nurses’ age and MSDs, especially concerning different age-groups as such differences could be relevant for preventive measures. Studies also indicate that physical job demands common in nursing are associated with an increased risk of MSD: frequent lifting of heavy loads, patient transfers, extreme flexion, bending, twisting and sudden movements in non-neutral positions increase the risk of back complaints and back injuries (Engkvist et al., 1998; Hoogendoorn et al., 2000; Lipscomb et al., 2011; Long et al., 2012; Punnett and Wegman, 2004; Trinkoff et al., 2001). Lifting and bending were shown to be associated with arm and neck complaints (Engels et al., 1996). Working with arms and hands in awkward positions and repetitive motions with hands/wrists are associated with pain in hands, arms and shoulder (Punnett et al., 2000; Trinkoff et al., 2003). However, study results about MSDs and the association with physical job demands in nursing are almost exclusively based on self-reports. Therefore, observed relationship might be over- or underestimated due to common method bias (Podsakoff et al., 2003). A systematic bias of study results consequently can lead to suboptimal conclusions for effective measures to prevent MSDs (Trinkoff et al., 2003). Research efforts using more objective measures to assess MSDs in nursing, e.g. a physical examination for health effect and/or workplace observations for health risks, are rare. Knibbe and Friele (1999) and Warming et al. (2009) tried to overcome the shortcomings of questionnaire data to assess health risks (physical job demands) by logbooks-registration. They showed an association of nursing tasks and MSDs. The present study aims to overcome some shortcomings of selfreporting questionnaires in the documentation of health effects. We applied an expert-based, standardized physical examination to assess MSDs. Drawing on a sample of nurses in inpatient care, we sought to address the following questions: - Are there differences between three age-groups (<35, 35e44, 45 years) concerning the frequency of MSDs? - Are there age-dependent differences in the location of MSDs? - Are physical job demands in nursing related to MSDs? - Does the strength of the relation between physical job demands and MSDs differ between three age-groups?
2. Methods and material 2.1. Design Data were gathered in a cross-sectional study design among hospital nurses working in a University Hospital in Southern Germany by means of a physical examination and a self-reporting questionnaire. To allow matching of the questionnaire data with the data of the physical examination, pseudonymisation was carried out by assigning a five-digit code. Participation in any part of the investigation was voluntary and the voluntary time counted as working time. The study was approved by the Ethics Committee of the Faculty of Medicine, Munich University. 2.2. Sample 952 nursing professionals were invited in writing to take part in the survey and the physical examination. The nursing units were selected by the nursing management: all intensive care units, all operation units, all anesthesia units, three general inpatient wards and the unit for patient transfers were selected; leading to an
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overrepresentation of critical care nurses and an underrepresentation of nurses from general inpatient wards in the sample. 2.3. Procedure The nursing professionals were informed in advance about the objective and the procedure of the project. The questionnaire and the consent forms (survey and physical examination) were sent together with the invitation. Those who decided to take part in the survey and/or the physical examination had to send back the written informed consent. Participation in any part of the investigation was independent from one another (Table 1). The deadline for returning the questionnaire was two weeks after the invitation date. The return was anonymous. An appointment with the physician was made with those participants who had sent back their written informed consent to the physical examination. The examination was divided into a detailed structured interview and a systematic orthopedic screening examination of all body sites. 2.4. Measures Musculoskeletal disorders (MSD) were assessed with a screening examination suggested by Spallek et al. (fokusÓ) which was based on widely accepted clinical tests summarized in Table 2 (Spallek et al., 2007). The examination focuses on musculoskeletal impairment, restriction of mobility, and pain, which are the most relevant symptoms of MSD in occupational contexts. It is recommended by the German Federal Institute for Occupational Safety and Health (FIOSH, BAuA) as a systematic orthopedic examination under occupational conditions. This recommendation is given associated with the national implementation of the EU manual handling directive (90/269/EEC) for the public services in Germany (Steinberg et al., 2006). Results were documented on the basis of the neutral-zeromethod and comparing both corporal sides. The neutral-zeromethod assesses the mobility of joints in angular degrees as the maximum deflection from a defined, neutral starting position (0 ). All examinations were carried out by one specially trained physician applying uniform diagnostic criteria. Further, data about prevention of activity in the preceding 12 months due to musculoskeletal problems at the neck, shoulders, elbows, hands, lower back, knees and feet/ankles were obtained via questionnaire, measured as a yes/no item for each body site [“During the last 12 months have you been prevented from carrying out normal activities (e.g. job, housework, hobbies) because of this trouble?”]. Work- and not-work-related accidents were assessed for each of the examined body site by the doctor during the interview, e.g.: “Did you ever have an accident that caused a shoulder injury?” (0 ¼ “no”, 1 ¼ “yes”). If “yes”: “Was it an occupational injury?” (0 ¼ “no”, 1 ¼ “yes”).
Table 1 Consent to the participation in the survey and/or the physical examination (N ¼ 953). Survey
Physical examination
Yes No
Yes
No
264 (27.7%) 165 (17.3%)
9 (0.9%) 515 (54.0%)
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Table 2 Orthopedic screening examination by Spallek et al. e criteria for positive findings. Body site and test
Cervical spine Rotation in neutral position Lateral bending Extension/flexion Thoracic/Lumbar spine Flexion: distance of fingers from floor Lateral flexion Lateral rotation Pain on percussion /pressure Standing/Walking on toes and heels
Balancing on one leg
Standing up from squat
Shoulder/Arm Abduction, external rotation: thumb on the back of the neck, pointing downwards Adduction, internal rotation: hand behind the back (like tying an apron), thumb upwards Abduction: place the hand on the opposite shoulder Arm/Hand Actively gripping and lifting a chair in pronation and supination
Criteria for positive finding Right
Left
<70
<70
<45 <45
<45 <45
>15 cm <30 <30 Yes
<30 <30
Impossibility Weakness Difference to left side >6 s Impossibility Weakness Impossibility Weakness of the hip/thigh Difference to left side
Impossibility Weakness Difference to right side >6 s Impossibility Weakness Impossibility Weakness of the hip/thigh Difference to right side
tool (Büssing and Glaser, 2000; Weigl et al., 2010). Participants were asked to rate the degree, to which their work requires them to lift heavy loads with two items (“In this job one consistently has to lift heavy patients” and “. to lift heavy objects.”). Uncomfortable body postures were evaluated with four items (“In this job one consistently has to lift objects far from the body.”, “. to work in standing position for several hours a day.”, “. to bend several times every hour.“, “.to maintain uncomfortable working positions.”). Items used a 5-point Likert scale ranging from 1 ¼ “not at all” to 5 ¼ “to a very great extent”. Internal consistency (Cronbach’s alpha) of the scale was 0.83. The overall scale was categorised as low (scale mean <2.5), moderate (2.5e3.5), and high (>3.5) physical job demands. The lowest category served as a reference category in the regression analyses. Demographic variables were age, gender (0 ¼ male, 1 ¼ female), and years in nursing, which were collected via questionnaire. Confounding variables were exercise, smoking and body mass index (BMI). Exercise was measured as a single item: “How often are you doing physical activities for at least 20 min that make you at least sweat a little bit or be short of breath (e.g., sports, hiking, dancing)?” The Item used a 5-point scale ranging from 1 ¼ “daily” to 5 ¼ ”never”. Smoking was assessed with one question: “Do you smoke?” (0 ¼ “no”, 1 ¼ “yes”). BMI was calculated according to the formula BMI ¼ m/l2 (m ¼ body weight in kg, l ¼ body height in m). Exercise and BMI were included as continuous variables into the analysis.
>0 cm difference between right and left side
2.5. Data analyses >2 cm difference between right and left side
Difference between right and left side
Impossibility Impossibility Weakness Weakness Difference to left side Difference to right side
Knee/Ankle Squatting as low as possible with heels on the floor and subsequently standing up slowly Balancing on one leg
Weakness of the foot Weakness of Difference to left side the foot Difference to right side <6 s <6 s Difference to left side Difference to right side Hopping on one leg Impossibility Impossibility Weakness of the foot Weakness of the Difference to left side foot Difference to right side Walking on toes and heels Impossibility Impossibility Weakness of the foot Weakness of the foot Difference to left side Difference to right side Standing on feet’s outer edges Impossibility Impossibility Difference to left side Difference to right side
Accordingly, the operational case definition of an MSD at a specific body site in this study was based on the following criteria: (i) a positive result in one of the relevant tests for this body site (Table 2) or manifestation of pain during the examination maneuvers, and (ii) prevention of activities (work, household, leisure) by musculoskeletal problems at the same body site in the preceding 12 months, and (iii) no not-work-related accident at the relevant body site in the past. Physical job demands and uncomfortable body postures were assessed with a total of 10 items. Physical job demands were assessed with a German six-item scale of the hospital work analysis
Data was entered twice in a common spreadsheet program. Consistency, logic and range checks of the data were carried out. SPSS 19.0 was used for statistical analyses. To perform further analyses, age was categorized into three groups: <35, 35e44 and 45 years. To investigate the differences between the three age-groups regarding the prevalence of MSDs, Chi-square-tests were used. The odds of observed MSDs were analyzed in respect to the overall physical job demands scale with multivariate hierarchical logistic regressions. In the first step of the regression, analysis the sociodemographic (age, gender, years in nursing) and confounding variables (exercise, smoking, BMI) were included in the model. In the second step incremental effects of physical job demands were tested. Beside an analysis of the total sample, we computed separate regression models of three agegroups to test for age-specific effects of physical job demands in nursing on MSDs. To account for multi-collinearity, all continuous predictor variables were mean centered (Aiken and West, 1991). 3. Results 3.1. Demographic, employment, and health behaviour characteristics The 273 nursing professionals who took part in the physical examination did not differ from the total sample of participating nurses (Table 3) regarding gender, but were older: 39.3 years (standard deviation, SD ¼ 11.7) in the physical examination group, 38.5 years (SD ¼ 11.3) in the total sample (T ¼ 1.94, p ¼ 0.053). Participants’ age ranged from 21 to 63 in both groups. Additionally, nurses who took part in the physical examination had more years in the nursing profession (19.1 years/SD ¼ 11.7; total sample: 18.2 years/SD ¼ 11.0; T ¼ 2.4, p ¼ 0.015). 136 (49.8%) nurses were from intensive care units (pediatric and adult), 58 (21.2%) from the operating theatre (pediatric and adult), 41 (15.0%) from anesthesia wards or units (pediatric and adult) and 34 (12.5%) from general inpatient wards. 4 (1.5%) male nurses were from the unit responsible for patient transfers in the operating
B. Heiden et al. / Applied Ergonomics 44 (2013) 652e658 Table 3 Descriptive statistics of the participants in the physical examination.
Age Stature Weight BMI Years in nursing Years in this hospital Years in current job position Fitness
Mean (SD)
Range
39.31 (11.65) years 1.69 (0.08) m 70.77 (14.65) kg 24.85 (4.6) kg/m2 19.11 (11.66) 12.69 (9.46) 10.07 (8.68) 1e2 per week
21e63 years 1.50e1.92 m 45e137 kg 16e46 kg/m2 2e45 0e42 0e35 Never to daily
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shoulders (6.9%), and knees (2.2%). Feet/ankles and elbows/hands were least affected (1.5%; 1.1%). In 21 (7.7%) of the participants MSDs were detected at more than one body site, in 5 (1.8%) at more than two, and in 3 (1.1%) at more than three body sites. 22 (8.1%) participants had an accident with an injury of the neck in the past, 16 (5.9%) of the shoulders and 9 (3.3%) of the lower back e none of them was work-related. 68 (25%) participants reported an accident with an injury of the feet/ankles, 60 (22%) of the elbows/ hands and 49 (18%) of the knees e one of each was work-related.
Number (%)
3.3. Age and MSD
Gender Female Male Age-groups <35 years 35e44 years 45 years Unit/Ward Intensive care Anesthesiology Operating room General ward Patient positioning Full-time Part-time Smoker Non-smoker
232 (85.0%) 41 (15.0%) 112 (41.0%) 63 (23.1%) 98 (35.9%) 136 41 58 34 4 201 66 69 204
(49.8%) (15.0%) (21.2%) (12.5%) (1.5%) (75.3%) (24.7%) (25.1%) (74.2%)
rooms. 232 (85.0%) nurses were female and 41 male (15.0%). Considering three age-groups, 112 nurses were <35 years (41.0%), 63 between 35 and 44 years (23.1%) and 98 45 years (35.9%). The nurses had an average BMI of 24.85 kg/m2 (SD ¼ 4.6). Most of them reported exercising once or twice a week (corresponding to a mode of 3). 69 (25.1%) nurses were smokers. 3.2. Prevalence of MSDs, based on results of a physical examination 47 (17.2%) participants showed MSDs according to our case definition at one body site at least. Women were more often affected than men (17.7% vs. 14.6%), but the difference was not significant [c2 (df ¼ 1, N ¼ 273) ¼ 0.226, p ¼ 0.635]. Participants with a positive result at a specific body site in the physical examination also reported prevention of activity because of complaints at that body site in 32.3% (neck) to 75.0% (feet). In contrast 77.6% (lower back) to 93.9% (feet/ankles) of those participants with a negative physical examination result also did not report any complaints at that body site. In general, self-reported complaints and results of the physical examination at a specific body site were in accordance, but varying from 67.5% (lower back) to 93.3% (feet/ankles). According to the operational case definition (Table 4), MSDs of the lower back (8.7%) were most frequent, followed by neck (7.3%),
The frequency of having at least one MSD significantly increased with age, c2 (df ¼ 2, N ¼ 273) ¼ 28.27, p ¼ 0.000. There is no significant increase of MSDs from the young (<35 years) to the middle (35e44 years) age-group, but from the young to the old age-group (45 years), [c2 (df ¼ 1, N ¼ 208) ¼ 25.68, p ¼ 0.000], and also from the middle to the old age-group [c2 (df ¼ 1, N ¼ 161) ¼ 8.18, p ¼ 0.004]. The three age-groups also differ significantly regarding the frequency of MSD at different body sites, showing a significant increase from the young to the old age-group for neck, shoulders and lower back (Table 5). Comparing the young and the middle agegroup, there is only a significant higher frequency of shoulder-MSD in the middle age-group. Comparing the middle and old age-group, there is a significant higher frequency of neck- and lower back-MSD in the older nurses. Although there are more knee-MSD-cases in the old age-group than in the young and middle age-group, this difference is not significant. 3.4. Physical job demands and MSDs The levels of reported physical job demands were comparable in all age-groups [c2 (df ¼ 2, N ¼ 273) ¼ 1.72, p ¼ 0.422]. High levels of reported physical job demands are significantly related with the risk of MSDs (indicated by odds, Table 6). The risk increases for high levels, but not for moderate levels of physical job demands relative to the reference category of low physical job demands. The effects of high levels of physical job demands exist over and above the effects of sociodemographic variables, health related behaviour (exercise, smoking) and body mass. Physical job demands are related with the increased risk of MSDs in nurses of the middle age-group, but not in the young and the old age-group (Table 7). 4. Discussion Objectivity in diagnosing MSDs is difficult to achieve as complaints may arise without any physical findings and physical findings may remain without complaints. So neither physical examination nor self-reporting questionnaires are reliable
Table 4 Number of participants per criterion of case definition, number of accidents and final number of cases.
Positive result in the physical examinationa Prevention of activities in the preceding 12 monthb Positive result in the physical examination plus prevention of activities in the preceding 12 month Accidents in the past Work-related Not-work-related a b
Neck (n ¼ 260)
Shoulders (n ¼ 256)
Elbows/Forearms/ Hands (n ¼ 255)
Lower back (n ¼ 259)
Knees (n ¼ 254)
Feet/Ankles (n ¼ 252)
65 (25.0%) 44 (16.9%) 21 (8.1%)
44 (17.2%) 35 (13.7%) 17 (6.6%)
11 (4.3%) 27 (10.7%) 6 (2.4%)
67 (25.9%) 69 (26.6%) 26 (10.0%)
28 (11.0%) 32 (12.6%) 12 (4.7%)
8 (3.2%) 21 (8.3%) 6 (2.4%)
0 22
0 16
1 60
0 9
1 49
1 68
Positive result in one of the relevant tests for the body site or manifestation of pain during the examination maneuvers. Prevention of activities (work, household, leisure) by musculoskeletal problems at the body site in the preceding 12 months.
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B. Heiden et al. / Applied Ergonomics 44 (2013) 652e658
Table 5 Frequency of musculoskeletal disorders (MSD) by location and age-group. MSD
Age-groups (in years) 35 (a)
35e44 (b)
45 (c)
c2 (df)
p-value
Compared age-groups
Neck Yes No
0.9% (n ¼ 1) 99.1% (n ¼ 109)
4.8% (n ¼ 3) 95.2% (n ¼ 60)
15.3% (n ¼ 15) 84.7% (n ¼ 83)
2.633 4.294 15.129
0.105 0.038 0.000
ab bc ac
Shoulder Yes No
0.9% (n ¼ 1) 99.1% (n ¼ 110)
7.9% (n ¼ 5) 92.1% (n ¼ 58)
12.2% (n ¼ 12) 87.8% (n ¼ 86)
5.975 0.754 11.482
0.015 0.385 0.001
ab bc ac
Elbows/Forearms/Hands Yes 0.0% (n ¼ 0) No 100% (n ¼ 110)
1.6% (n ¼ 1) 98.4% (n ¼ 61)
2.0% (n ¼ 2) 98.0% (n ¼ 96)
1.785 0.38 2.267
0.182 0.846 0.132
ab bc ac
Lower back Yes No
2.7% (n ¼ 3) 97.3% (n ¼ 109)
3.2% (n ¼ 2) 96.8% (n ¼ 61)
19.4% (n ¼ 19) 80.6% (n ¼ 79)
0.036 8.888 15.559
0.850 0.003 0.000
ab bc ac
Knees Yes No
0.9% (n ¼ 1) 99.1% (n ¼ 109)
0.0% (n ¼ 0) 100% (n ¼ 63)
5.2% (n ¼ 5) 94.8% (n ¼ 92)
0.576 3.352 3.301
0.448 0.067 0.069
ab bc ac
Feet/Ankles Yes No
0.0% (n ¼ 0) 100% (n ¼ 112)
1.6% (n ¼ 1) 98.4% (n ¼ 62)
3.1% (n ¼ 3) 96.9% (n ¼ 95)
1.788 0.344 3.478
0.181 0.558 0.062
ab bc ac
Total Yes No
5.5% (n ¼ 6) 94.5% (n ¼ 104)
12.7% (n ¼ 8) 87.3% (n ¼ 55)
32.7% (n ¼ 32) 67.3% (n ¼ 66)
2.826 8.178 25.677
0.093 0.004 0.000
ab bc ac
instruments by themselves. This cross-sectional study addresses the effects of physical job demands and age in terms of MSDs in nurses by assessing both, physical findings and complaints. Studies that assess MSDs in nursing by integrating a physical examination are rare. Most studies are exclusively based on self-reporting questionnaires to assess both e exposures and health effects. So this investigation tries to overcome an important shortcoming in the field of health effects. The MSD most frequently observed was located in the lower back, followed by neck/shoulders, and knees. This ranking of location matches with existing study results assessed by selfreports, but relative frequencies in our study were much lower (Ando et al., 2000; Daraiseh et al., 2010; Engels et al., 1996; Smith et al., 2003a; Trinkoff et al., 2003). One reason for this rather low frequency may be due to the restrictive case definition and Table 6 Adjusted odds ratio of musculoskeletal disorders in nurses by level of reported physical job demands, sociodemographic variables, health related behaviour, and body mass (N ¼ 273). Variable
Musculoskeletal disorders (MSD) OR (95% CI)
Age (continued) Gender Male Female Years in profession (continued) Exercise (continued) Smoking No Yes Body mass index (continued) Physical job demands Low (mean <2.5) (n ¼ 42) Moderate (mean 2.5e3.5) (n ¼ 123) High (mean >3.5) (n ¼ 98)
3.68 (1.11e12.18)
Notes. OR: odds ratio; CI: confidence interval.
1.00 1.77 (0.55e5.75) 0.87 (0.30e2.57) 1.11 (0.74e1.67) 1.00 0.84 (0.33e2.17) 0.92 (0.68e1.23) 1.00 2.63 (0.71e9.67) 5.70 (1.55e20.96)
multi-method assessment of MSDs. It is possible that especially the criterion “prevention of activities” resulted in a selection of rather serious cases and therefore smaller numbers. However, comparisons between studies must be handled with care as the methods used to assess MSDs as well as the case definitions do not completely correspond (Punnett and Wegman, 2004). Our study provides further information to the evidence base of age effects on MSDs in nursing professionals (Ando et al., 2000; Da Costa and Vieira, 2010; Engels et al., 1996; Lagerstrom et al., 1995; Leighton and Reilly, 1995; Menzel, 2004; Venning et al., 1987). Our data support an association of age and MSDs in nursing professionals, with a general increase up to the oldest age-group (45 years). MSDs in this age-group were mainly located in the back, neck and shoulders. A noticeable result is significant increase of most MSDs from the middle to the old age-group, but only one significant difference e in shoulder-MSDs e between the young and the middle age-group. There seems to be an earlier onset of shoulder-MSDs. Considering the most frequent locations of MSDs in the three age-groups e middle and old age-group: shoulder; Table 7 Age specific adjusted odds ratios of musculoskeletal disorders (MSD) by level of reported physical job demands in nurses. Physical job demands by age-groups Nurses <35 years (n ¼ 106) Low and moderate (mean 1e3.5) (n ¼ 63, 59%) High (mean >3.5) (n ¼ 43, 41%) Nurses 35e44 years (n ¼ 62) Low and moderate (mean 1e3.5) (n ¼ 43, 69%) High (mean >3.5) (n ¼ 19, 31%) Nurses 45 years (n ¼ 95) Low and moderate (mean 1e3.5) (n ¼ 59, 62%) High (mean >3.5) (n ¼ 36, 38%)
Musculoskeletal disorders (MSD) OR (95% CI) 1.00 1.23 (0.18e8.49) 1.00 10.31 (1.46e72.81) 1.00 2.09 (0.81e5.42)
Notes. Models are adjusted by gender, years in profession, exercise, smoking behaviour, body mass index, OR: odds ratio; CI: confidence interval.
B. Heiden et al. / Applied Ergonomics 44 (2013) 652e658
young age-group: lower back e our results agree with the review of Da Costa and Vieira (2010). It showed some evidence for older age nurses being exposed to a risk factor for neck- and shoulder-MSDs. For MSDs of the lower back, younger age nurses appear to be exposed to a risk factor. It is remarkable that the steep increase in MSDs that we found in older nurses exists despite a potential “healthy worker effect”. One might speculate that nurses who are severely affected by MSDs change their job or take early retirement. In consequence, the actual number of nurses with MSDs and therefore the risk of older nurses to suffer MSD may be greatly underestimated in our study. More alarmingly are our findings in nurses >45 years, which show a higher prevalence of MSDs in comparison to both other agegroups. Furthermore, our study provides evidence that high physical job demands in nursing are related to MSDs. As expected, and documented by other studies (Harcombe et al., 2010, 2009; Josephson et al., 1997; Trinkoff et al., 2003), a general association between MSDs and physical job demands was evident, but some details were contradicting. Trinkoff et al. (2002) for example observed an increased risk of MSD for moderate and high physical job demands. In the present study, only physical job demands at high levels were associated with an increased risk of MSDs. This discrepancy may be explained by common method variance as Trinkoff et al. (2003) assessed data exclusively by self-report (Podsakoff et al., 2003). But also differences in the methods, e.g. grading of physical job demands, wording of the questions and/or differences in case definitions for MSDs must be taken into account (Punnett and Wegman, 2004). Considering the three age-groups there was only a significant association between physical job demands and MSDs in the middle age-group, but not in the youngest nor the oldest age-group. These differences between the age-groups may indicate that the years between the age of 35 and 44 are a special vulnerable phase for nurses to develop MSDs due to physical job demands in nursing, corresponding to the theory of “premature physiological aging“ of the muscular skeletal system (Barbini and Squadroni, 2003.). High physical demands in nursing, e.g. physical patient handling, may cause overload to the musculoskeletal system, with the effect of a “cumulative trauma”, and thus may result in a premature degenerative process (Kumar, 2001; Menzel et al., 2004). Nevertheless, it is important to keep in mind that the number of cases was quite low. Also it was a cross-sectional study and therefore no causal relation can be drawn. Our study has several limitations: even though this study aimed to overcome the predominance of questionnaire data in research on MSD in nursing, data on physical job demands are still based on self-reports. Thus, objectivity of this information might be questioned. However, a validation study on the used instrument demonstrated a high convergence between job incumbents’ ratings and external observations (Büssing and Glaser, 2002). Nevertheless, efforts should be made in future studies to obtain further information on physical job demands with additional instruments, e.g. structured observations. Because of non-probability, the low participation rate and the small sub-group consent to the physical examination potential sample selection bias may affect the external validity, and thus representativeness of our findings. However, we expect only minor effects of sample selection bias on our study results for the following reasons: we performed a post hoc analysis which revealed that our study sample and nurses who decided not to participate in the physical examination did not differ in physical health status as measured with the SF-12 questionnaire (Ware et al., 1996). Moreover, despite the underrepresentation of nurses working in general inpatient wards, our study sample is similar to the typical
657
German workforce in nursing regarding age, gender structure and years in nursing (Isfort and Weidner, 2010). Therefore, it seems plausible that our findings may be replicable in other nursing settings. Information bias cannot completely be ruled out, especially as the nurses had to be informed in advance about the study objectives. We used the following measures to minimize information bias in our study: we avoided the main cause of information bias by gathering the information from all participants in the same way (Grimes and Schulz, 2002). As the physician did not know the survey results on physical stressors at the time of the examination we could also exclude diagnostic suspicion bias, i.e. caused by a more intensive search for MSDs due to positive results about exposure in the questionnaire (Grimes and Schulz, 2002). Moreover, it is impossible that the results of the physical examination influenced nurses’ response behaviour on physical work stressors as the survey took place before the physical examination. Finally, the representativeness of the observed age effects may be restricted to the three age-groups of our study. We used this specific definition of age-groups for the following reasons: nurses remain on average a rather short time in their profession (10- to 15year), so the group <35 years was considered separately as nurses may have already left the nursing profession around this time period. Nurses 45 years were chosen as the third group because there is evidence that they report considerable reduced work ability at this age (Camerino et al., 2006; Hasselhorn et al., 2003). However, further research may replicate our findings using a different definition of age-groups. 5. Conclusions The interaction between the age of nurses, their physical work demands, and the risk and location of MSD seems to be complex and multifaceted. Our study shows that older nurses have to suffer an increased risk of MSD. At the same time, the study indicates that even the youngest age-group suffers from MSD. Finally, we observed that physical job demands in nursing are a risk factor for MSD especially in the middle age-group. Thus, in terms of the design of adequate interventions for health promotion, our study’s results emphasize the importance of an early onset of prevention activities regarding MSDs and their extension over the whole working life. According to our results, age-specific priorities in prevention activities should be reconsidered. As the causes for MSDs are multi-factorial a wide range of detrimental working conditions should be optimized and redesigned. Ethics Approval to conduct the research study related to this paper was obtained from the Ethics Committee of the Faculty of Medicine, Munich University (No 256-09). Funding This study was supported by a grant from the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG): MU 3079/11 and the Munich Center of Health Sciences. The project is part of the DFG priority program 1184 “Age-differentiated work systems”. Competing interests None.
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