IJE Advance Access originally published online on May 29, 2008
International Journal of Epidemiology 2008 37(5):1181-1189; doi:10.1093/ije/dyn085
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Cultural differences in musculoskeletal symptoms and disability
1 Guy's and St Thomas’ NHS Foundation Trust and Division of Health and Social Care, King's College London, London, UK.
2 MRC Epidemiology Resource Centre, University of Southampton, Southampton General Hospital, Southampton, UK.
* Corresponding author. MRC Epidemiology Resource Centre, Southampton General Hospital, Southampton SO16 6YD. E-mail: dnc{at}mrc.soton.ac.uk
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Abstract |
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Objectives To test the hypothesis that cultural factors such as health beliefs and expectations have an important influence on common musculoskeletal symptoms and associated disability, we compared prevalence rates in groups of workers carrying out similar physical activities in different cultural settings.
Methods We conducted a cross-sectional survey at factories and offices in Mumbai, India and in the UK. A questionnaire about symptoms, disability and risk factors was administered at interview to six occupational groups: three groups of office workers who regularly used computer keyboards (165 Indian, 67 UK of Indian subcontinental origin and 172 UK white), and three groups of workers carrying out repetitive manual tasks with the hands or arms (178 Indian, 73 UK of Indian subcontinental origin and 159 UK white). Modified Cox regression was used to calculate hazard ratios (HRs) for the prevalence of symptoms and disability by occupational group, adjusted for differences in sex, age, mental health and job satisfaction.
Results Reported occupational activities were similar in the three groups of office workers (frequent use of keyboards) and in the three groups of manual workers (frequent movements of the wrist or fingers, bending of the elbow, work with the hands above shoulder height and work with the neck twisted). In comparison with the Indian manual workers, the prevalence of back, neck and arm pain was substantially higher in all of the other five occupational groups. The difference was greatest for arm pain lasting >30 days in the past year in UK white manual workers (HR 17.8, 95% CI 5.4–59.1) and UK manual workers of Indian subcontinental origin (HR 20.5, 95% CI 5.7–73.1). Office workers in India had lower rates of pain in the wrist and hand than office workers in the UK. Only 1% of the Indian manual workers and 16% of the Indian office workers had ever heard of ‘RSI’ or similar terms, as compared with 80% of the UK workers.
Conclusions Our findings support the hypothesized impact of cultural factors on common musculoskeletal complaints. Current controls on hazardous physical activities in the workplace may not have the benefits that would be predicted from observational epidemiology.
Keywords Back pain, neck pain, arm pain, RSI, WRULD, beliefs, expectations
Accepted 16 April 2008
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Introduction |
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In western countries, painful disorders of the back, neck and upper limb are a major cause of morbidity, disability and incapacity for work. Often, they are attributed to occupational activities such as lifting, bending, use of computer keyboards and other repetitive manual tasks. Legislation in the European Union, therefore, requires employers to control health risks in the workplace from manual handling and from work with computers.1,2 Psychological risk factors also have an important role.3 For example, in prospective longitudinal studies, low mood has been found to predict the subsequent incidence of both back4 and arm pain.5
There remain, however, important features of the descriptive epidemiology of musculoskeletal complaints that cannot adequately be explained by known risk factors. These include a more than 7-fold increase in rates of incapacity for work because of back disorders in Britain between 1953 and 19926 (despite a reducing prevalence of heavy physical work), and a major epidemic of disabling arm pain in Australia during the early 1980s7 that was not paralleled in other countries.
Such observations have prompted the theory that painful disorders of the back and arm are subject also to cultural influences, their chronicity and associated disability being importantly determined by societal beliefs and expectations about causation and prognosis. It has been proposed that they occur as a psychologically mediated response to an external trigger (such as an initiating acute injury) that is conditioned both by individual characteristics (such as low mood) and by cultural circumstances.8
If correct, this hypothesis would predict the prevalence of musculoskeletal complaints and associated disability to vary between countries according to differences in understanding of their causation and, in particular, in beliefs about the risks associated with occupational activities. To test this prediction, we compared rates of musculoskeletal symptoms and disability in workers from India and the UK, whose jobs involved similar physical demands.
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Methods |
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The survey focused on six groups of workers defined by combinations of job content (regular use of computer keyboards in offices/repetitive manual tasks with the hands and arms) and ethnicity (Indian/UK of Indian subcontinental origin/UK white). In India, the office workers were employed at a call centre, software house and other offices, while the manual group worked on production lines in engineering and the manufacture of soap and pharmaceuticals. All of the UK workers were employed by Royal Mail, either in offices or sorting mail by hand (classed here as a manual task). The initial selection of subjects in the UK was based only on occupation, but the large majority of participants were either white or of Indian subcontinental origin, and the remainder were excluded from the analyses presented in this article.
In each place of work, all eligible subjects (eligibility being based on work area) were identified by their manager, and approached by a research assistant, who explained the study and invited them to take part. Those who agreed were then interviewed using a structured questionnaire that asked about: demographic characteristics; duration of employment in current occupation; whether or not an average working day involved each of six specified activities of the upper limb and neck; job satisfaction; sickness absence in the past year; mental health; knowledge and beliefs about musculoskeletal disorders and the occurrence, frequency and impact of pain at each of five anatomical sites (low back, neck, shoulder, elbow and wrist/hand) in the past year. The research assistants (one in India and one in the UK) were both trained by one of the authors (I.M.), who also monitored their interview technique periodically during data collection.
Mental health was assessed using the relevant subscale of the SF-36 questionnaire,9 and was graded to three levels defined by approximate thirds of the distribution of scores in all subjects combined. The questions about beliefs asked how strongly the participant agreed with statements of the form, ‘Your work may cause you to develop low back pain’. Similar questions were posed for each anatomical site of interest, and answers were classed as positive if the subject indicated that they ‘completely agreed’ or ‘tended to agree’. Knowledge about work-related musculoskeletal disorders was explored by the question, ‘Have you ever heard or read about repetitive strain injury (RSI), work-related upper limb disorder (WRULD) or cumulative trauma syndrome (CTS)?’ The questions on musculoskeletal symptoms were adapted from the modified Nordic questionnaire on musculoskeletal complaints.10
The questionnaire was originally drafted in English, translated into Marathi and then independently back-translated to English. After correction of errors revealed by the back-translation, both the English and Marathi versions were piloted in samples of Indian workers different from those used in the main survey. This revealed a problem with the interpretation of one of the SF-36 questions (‘During the past 7 days, have you been a nervous person?’), which was therefore omitted from the final questionnaire. In the main survey, all participants were interviewed in English apart from a subset of the Indian manual workers, who preferred to be interviewed in Marathi.
Data were analysed using STATA (version 9.2) software. For each anatomical site, we defined four outcome variables—pain lasting longer than a day at any time in the past month, pain on >30 days in the past year, disabling pain in the past year and pain leading to sickness absence in the past year. Pain was classed as disabling if it had caused difficulty with more than a specified number of activities of daily living. For example, low back pain was considered disabling if it had impaired at least three of: standing for longer than 15 min, cutting toe nails, getting up from the floor or a chair, getting dressed, doing normal jobs around the house and turning over in bed. A further set of four outcome variables was derived for ‘arm pain’, defined as pain in any of the shoulder, elbow or wrist/hand. In addition to generating simple descriptive statistics, we compared the prevalence of outcome variables by study group after adjustment for sex, age, mental health and job satisfaction. Estimates of relative risk (effectively prevalence rate ratios) were derived by modified Cox regression,11 and summarized as hazard ratios (HRs) with associated 95% CIs.
The protocol for data collection in the UK was approved by the Health and Safety Executive Research Ethics Committee. The protocol for data collection in India was approved by the chairman of the ethics committee at the PD Hinduja National Hospital and Medical Research Centre, Mumbai, who judged that it did not need to be reviewed by the full committee.
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Results |
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In total, interviews were completed by 855 (95.4%) of the 896 workers who were eligible to take part in the study, and after exclusion of 41 UK workers who were neither white nor of Indian subcontinental origin, 814 participants provided data for analysis. Table 1 gives a breakdown of the study sample according to occupational group and various other characteristics. The Indian manual workers and UK white workers (both manual and office) tended to be somewhat older than the other groups. All but one of the Indian manual workers were men, whereas at least 20% of the other groups were women. The large majority of participants had been employed in their current job for at least 1 year. Reported occupational activities were much as would be expected, with a high frequency of keyboard use in all three groups of office workers, and of other repeated movements of the wrist or fingers and repeated bending and straightening of the elbow in all three groups of manual workers. The latter also indicated a higher prevalence of work with the hand(s) above shoulder height (38–40%), and of work with the neck twisted (42–46%). Most participants were satisfied with their current job, particularly those in India. The proportion of workers with at least one spell of sickness absence in the past year was higher in the UK (68–77%) than in India (47 and 52%). Poor mental health was most common in UK manual workers [both white (46%) and of Indian subcontinental origin (51%)], and lowest in the Indian manual workers (14%). Most participants believed that their work could cause musculoskeletal pain to develop, UK workers rather more than those in India. However, knowledge of RSI and related terms differed markedly between the groups, ranging from 1% among the manual workers in India and 16% in office workers in India to 86% in UK white manual workers and 95% in UK white office workers.
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Table 2 shows the prevalence of pain at different anatomical sites by occupational group. Rates of symptoms among UK manual workers were generally similar, whether they were white or of Indian subcontinental origin. The same applied to UK office workers, except that frequent pain over the past year (>30 days in total) was reported less often by those of Indian subcontinental origin. Symptom rates among office workers in India were similar to those in the UK office workers of Indian subcontinental origin, except at the wrist/hand where they were less common. Most striking, however, were the much lower rates of symptoms at all sites among manual workers in India.
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This difference is apparent in Table 3, which shows risk estimates for various measures of low back pain from regression modelling. After adjustment for the expected associations with poor mental health, and also for sex, age and job satisfaction, the 1-month prevalence of low back pain in Indian manual workers was only about half of that in the other occupational groups. Disabling and frequent low back pain also occurred at less than half the frequencies observed in UK manual workers, but for these outcomes, differences from office workers were less consistent.
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For neck pain (Table 4), the risks among manual workers in the UK relative to those in India were larger than for low back pain, and highly significant statistically. Risks in office workers were also much higher (generally by more than a factor of three) than in Indian manual workers.
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For arm pain (Table 5), the pattern was similar, but with even larger differentials. For example, in comparison with manual workers in India, the relative risk of arm pain in the past month was 6.8 (95% CI 3.4–13.4) in UK manual workers of Indian subcontinental origin, and 5.6 (95% CI 3.0–10.6) in UK white manual workers.
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Repeat of the analyses for Tables 2–5
after exclusion of the minority of participants who had worked in their current job for <1 year produced similar results. To check for possible bias as a consequence of unsatisfactory translation of the questionnaire, we compared the prevalence of musculoskeletal outcomes among the manual workers in India according to the language in which they were interviewed. Low back pain was reported rather more often by Marathi speakers (n = 146) than by English speakers (n = 32), but otherwise there were no consistent differences. For example, the prevalence of arm pain in the past year was 15% among those interviewed in Marathi and 13% among those interviewed in English.
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Discussion |
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Our survey indicates major differences in the prevalence of musculoskeletal symptoms and associated disability between workers in India and the UK. These differences could not be explained by differences in established physical risk factors or mental health. Most striking were the substantially lower rates of arm pain among manual production line workers in India, only 1% of whom had ever heard of terms such as ‘RSI’. In the UK, rates of symptoms in workers of Indian subcontinental origin were generally similar to those in white workers, except that they tended to be less persistent.
A strength of our study was the high response rate from those eligible for inclusion. It is possible that a few workers were omitted from our sampling frame because they were absent from work at the time of the survey as a consequence of musculoskeletal disorders. However, it seems implausible that selection bias could explain the large differences in symptom prevalence that were observed.
Bias could also have occurred if questions about symptoms were understood differently in India and the UK. In particular, this might apply where interviews were conducted in different languages. However, we took special care to ensure that translation of the questionnaire was as accurate and understandable as possible, with back-translation and pre-piloting. Moreover, when we compared answers from Indian workers who were interviewed in Marathi and in English, symptom rates were much the same.
Nor could the observed differences in symptom prevalence be explained by confounding effects of known risk factors such as occupational physical activities, job satisfaction and mental health. By design, exposure to physical activities was much the same among the three groups of manual workers, and similarly among the three groups of office workers. Furthermore, the relative risks that we found (5- to 7-fold for arm pain) were substantially larger than those that have been reported for work activities in most previous investigations. Job satisfaction was lower and poor mental health more common in the UK than in India, but the differences in symptom prevalence persisted when adjusted for job satisfaction and mental health (Tables 3–5).
The prevalence of regional pain and disability in UK workers was broadly consistent with that reported in other recent surveys although case definitions have not been exactly the same.12–14 The observation that in the UK, rates of symptoms and disability were generally similar in white workers and those of Indian subcontinental origin indicates that the lower frequency among workers in India is unlikely to reflect genetic differences in susceptibility.
We cannot exclude the possibility that participants in India, and especially the manual workers, had less knowledge of ‘RSI’ and related terms simply because arm pain was relatively rare in their community. However, our findings are consistent with our prior hypothesis that societal beliefs about such illness and its causation importantly influence its occurrence. This accords with observations on ‘chronic whiplash injury’, another musculoskeletal disorder that varies in occurrence between countries and appears to be influenced by societal beliefs.15 As with low back pain and non-specific arm pain, there is generally no demonstrable underlying local pathology in ‘chronic whiplash injury’.
Evidence is also now accumulating that individual beliefs and expectations are important predictors of outcome in people suffering from back and arm pain.16,17 Moreover, in Victoria, Australia, an attempt to modify people's beliefs about low back pain through a media campaign was associated with a reduction in incapacity for work attributed to back disorders.18
Differences between the UK and India in the prevalence of musculoskeletal disorders may also have been influenced by economic factors such as the availability of sick pay and of financial compensation for presumed occupational injuries. However, differentials in the prevalence of sickness absence for musculoskeletal pain during the past year were much larger than for sickness absence overall.
If the hypothesized contribution of cultural factors to musculoskeletal symptoms and disability is correct, there are important practical implications. In particular, controls on hazardous physical activities in the workplace may not have the benefits that would be predicted from observational epidemiology. This is because while they reduce physical stresses on tissues, they may also reinforce beliefs that the activities controlled carry serious risks to health. Therefore, there is a need for research to extend our observations to a wider range of cultural settings, and to characterize in more detail the reasons for the striking differences in the prevalence of symptoms that we have observed. It will also be important to evaluate the impact of controls on hazardous occupational activities directly in experimental investigations rather than relying on potentially misleading extrapolation from risk estimates in observational studies.
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Data collection in the UK was supported by a grant from the Colt Foundation.
Conflict of interest: None declared.
KEY MESSAGES
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References |
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1 Council Directive 90/269/EEC of May 29. 1990 on the minimum health and safety requirements for the manual handling of loads where there is a risk particularly of back injury to workers.
2 Council Directive 90/270/EEC of May 29. 1990 on the minimum health and safety requirements for work with display screen equipment.
3 Hadler NM. Socioeconomics of back pain. Nat Clin Pract Rheumatol (2006) 2:230–31.[CrossRef][Web of Science][Medline]
4 Linton SJ. A review of psychological risk factors in back and neck pain. Spine (2000) 25:1148–56.[CrossRef][Web of Science][Medline]
5 Macfarlane GJ, Hunt IM, Silman AJ. Role of mechanical and psychosocial factors in the onset of forearm pain: prospective population based study. Br Med J (2000) 321:676–79.
6 Clinical standards Advisory Group. In: Epidemiology Review: The Epidemiology and Cost of Low Back Pain. (1994) London: HMSO.
7 Gun RT. The incidence and distribution of RSI in South Australia 1980-81 and 1986-87. Med J Aust (1990) 153:376–80.[Web of Science][Medline]
8 Coggon D. Occupational medicine at a turning point. Occup Environ Med (2005) 62:281–83.
9 Ware JE. SF-36 Health Status Questionnaire. (1989) Boston, MA: Institute for the Improvement of medical Care and Health, New England Medical Center Hospital, Quality Quest Inc.
10 Kuorinka I, Jonsson B, Kilbom A, et al. Standardised Nordic questionnaires for the analysis of musculoskeletal symptoms. Appl Ergon (1987) 18:233–37.[CrossRef][Web of Science][Medline]
11 Lee J, Chia KS. Estimation of prevalence rate ratios for cross-sectional data: an example in occupational epidemiology. Br J Indust Med (1993) 50:861–62.[Web of Science][Medline]
12 Palmer KT, Cooper C, Walker-Bone K, Syddall H, Coggon D. Use of keyboards and symptoms in the neck and arm: evidence from a national survey. Occup Med (2001) 51:392–95.[Abstract]
13 Walker-Bone K, Reading I, Coggon D, Cooper C, Palmer KT. The anatomical patterns and determinants of pain in the neck and upper limbs: an epidemiologic study. Pain (2004) 109:45–51.[CrossRef][Web of Science][Medline]
14 Palmer KT, Calnan M, Wainwright D, et al. Disabling musculoskeletal pain and its relation to somatisation: a community-based postal survey. Occup Med (2005) 55:612–17.
15 Malleson A. Whiplash and Other Useful Illnesses. (2002) Montreal and Kingston: McGill-Queen's University Press.
16 Boersma K, Linton SJ. Expectancy, fear and pain in the prediction of chronic pain and disability: a prospective analysis. Eur J Pain (2006) 10:551–57.[CrossRef][Web of Science][Medline]
17 Ryall C, Coggon D, Peveler R, Poole J, Palmer KT. A prospective study of arm pain in primary care and physiotherapy: prognostic determinants. Rheumatology (2007) 46:508–15.
18 Buchbinder R, Jolley D, Wyatt M. Population based intervention to change back pain beliefs and disability: three part evaluation. Br Med J (2001) 322:1516–20.
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  J. Adamson and K. Atkin Commentary: Culture and pain in the work place: the domain of occupational epidemiology? Int. J. Epidemiol., October 1, 2008; 37(5): 1189 - 1191. [Full Text] [PDF]
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