Back pain and work: Psychosocial factors. The evidence.
Below are a series of summaries of research that explores the effect of psychosocial factors on back pain. At the end of this article the search strategy used to identify relevant articles is outlined.
The impact of various physical, constitutional and psychosocial factors on back pain is a subject of confusion. Research can be difficult to find, challenging to understand, and hard to interpret. Relevant research is summarised below. The summaries represent the best of the available research.
Controversy about the contribution of work and other factors to back problems can interfere with the focus on return to work. We hope these summaries will inform, and in turn reduce disputation.
Not every available piece of research is presented. We focus on providing a broad range of information on the topic and condition. High quality studies have been given preference. Where there are a number of studies with similar findings the most recent research has been included.
While the research survey below is comprehensive, each individual case and situation is different. The condition, the work an employee does and has done, how the is work done, how long they have performed the activities, was there an identifiable injury, and if so, how severe was the incident? How old is the person, what is their past medical history, what psychosocial factors influence the situation?
We are working on summarising a broad range of research on work contribution to various medical conditions. The research below will be transferred to a website dedicated to 'work causation' matters in the second half of 2009.
Byrns, G., J. Agnew, et al. (2002). "Attributions, stress, and work-related low back pain." Appl Occup Environ Hyg 17(11): 752-64.
Summary
This study looks at the association between low back pain (LBP) and individuals’ perceptions of the causes of their pain. The researchers examined 278 female workers from a men’s garment factory. They wanted to:
Compare the self-reported symptoms of workers who attribute their LBP to internal factors with those of workers who attribute their pain to external factors (such as job tasks or ‘fate’); and
See whether garment workers are at a high risk of developing LBP.
72% of the women studied reported having LBP at some time in their life. 36% reported having LBP due to occupational causes that was serious enough to limit movement or interfere with work.
Workers with a low knowledge of LBP and causation were more likely to score low in internal attribution and high in attributing LBP to luck or fate (OR 3.7 (95% CI 2.0-6.7). This finding may explain why back schools report different results of success. Depending on the individuals existing knowledge and attribution of LBP the effect of a back school may differ.
Furthermore, workers with high scores in job control tended to also have high scores in social support from their supervisors. Those workers scored low in LBP (OR 0.23 (95% CI 0.08-0.66)).
The researchers concluded that the attribution model provides a useful framework for understanding LBP, and could assist with the development of interventions aimed at LBP prevention.
Hartvigsen, J., S. Lings, et al. (2004). "Psychosocial factors at work in relation to low back pain and consequences of low back pain; a systematic, critical review of prospective cohort studies." Occup Environ Med 61(1): e2.
Summary
This article reviews 40 studies (1990-2000) that look at the associations between psychosocial workplace variables, low back pain (LBP) and the consequences of LBP. Of the studies (drawn from Medline, Psychinfo and OSHROM databases), ten were of high quality.
Of these high quality studies:
- Four looked at the relationship between LBP and perception of work. Three of those reported no association, while one found a positive association (OR 1.2).
- Three looked at the relationship between LBP and organisational aspects of work. Only one reported a positive association (2.19).
- Three looked at the relationship between LBP and social support at work. All three reported no association.
- Two looked at the relationship between LBP and stress at work, of which one reported a strong positive association (OR 2.68-2.70).
- Six examined the consequences of LBP and perception of work. Three reported a positive association (OR 1.2-1.95), and three reported no association.
- Four examined the consequences of LBP and organisational aspects of work, of which none reported an association.
- Five examined the consequences of LBP and social support at work. Two reported an association (OR 3.4-5.75).
- One examined the consequences of LBP and stress at work and found no association.
Overall, the researchers found moderate evidence for no positive association between LBP and; perception of work, organisational aspects of work, and social support at work. Insufficient evidence was found for an association between stress at work and LBP.
Insufficient evidence was also found for an association between the consequences of LBP and perception of work. Strong evidence was found for no association between the consequences of LBP and organisational aspects of work. Moderate evidence was found for an association between the consequences of LBP and both social support at work and stress at work.
Hoogendoorn, W. E., P. M. Bongers, et al. (2001). "Psychosocial work characteristics and psychological strain in relation to low-back pain." Scand J Work Environ Health 27(4): 258-67.
Summary
This three-year follow up study examines 861 workers from various companies in the Netherlands. The researchers were interested in the risk of low back pain (LBP) associated with different psychosocial work characteristics. Both blue and white collar workers were studied.
26.6% of the participants reported an episode of LBP at some point during the study. The researchers found a 1.3- to 1.6-fold increase in risk of LBP for workers with:
- High quantitative job demands;
- High conflicting demands;
- Low supervisory support; and
- Low co-worker support.
- However these associations were either borderline, or not statistically significant.
No relation between LBP and low decision authority or low skill discretion was found.
When the researchers looked only at workers who had been employed in their current job for 5 years or less, stronger associations were found between LBP and medium or high quantitative job demands, and for low and medium low supervisory support. This suggests the presence of healthy worker effect, which means that those workers who suffered from frequent episodes of LBP may have already resigned from their jobs.
Hoogendoorn, W. E., M. N. van Poppel, et al. (2000). "Systematic review of psychosocial factors at work and private life as risk factors for back pain." Spine 25(16): 2114-25.
Summary
This is a review of studies published between 1966 and 1997 about the relationship between psychosocial factors at work and the occurrence of back pain. The researchers found 13 studies that met their inclusion criteria. Of these:
- Three looked at work pace but the findings were inconsistent.
- One looked at qualitative job demands (including conflicting demands, interruption of tasks, and intense concentration for long periods). There was insufficient evidence for a relation with back pain.
- Four looked at job content and all reported that it had no significant statistical effect on back pain.
- One looked at job control. There was no effect on back pain except in blue collar women, for whom low work control had a positive effect on both low back symptoms and clinical findings. However the researchers concluded there was insufficient evidence for a relation because there was only one study available.
- Five looked at social support in the workplace. Of these, four reported a positive association between low social support and back pain with a risk estimate of 1.3-1.9.
- Seven looked at job satisfaction. In five of these a positive statistically significant relation was found between low job satisfaction and back pain with a risk estimate of 1.7-3.0.
The authors concluded that some evidence was found for a relation between back pain and both low social support in the workplace and low job satisfaction. However, while psychosocial factors seem to play some role in back pain, the role of specific factors has not yet been firmly established.
Mielenz, T. J., J. M. Garrett, et al. (2008). "Association of psychosocial work characteristics with low back pain outcomes." Spine 33(11): 1270-5.
Summary
This study analysed the association between recovery outcomes after low back pain episodes and; social support from co-workers, job task satisfaction and social support from a supervisor. When calculating these associations, the analysis took into account biomechanical demands at work, previous episodes of LBP, duration of LBP and general health.
The researchers interviewed 295 patients with acute low back pain four times: at baseline and then two, four and eight weeks after the onset of LBP. The primary outcome measure was the time it took to achieve self-assessed functional recovery.
There was a weak association between less social support from co-workers and acute LBP recovery (RR 1.55 (95% CI 1.04-2.34). Those with less social support were at a 1.5 times greater risk of not recovering from LBP within 8 weeks than those with normal or high social support.
There was no association between dissatisfaction with job tasks or lack of social support from a supervisor and LBP outcome. No interaction effect was found for biomechanical demands and psychosocial work characteristics.
Torp, S., T. Riise, et al. (2001). "The impact of psychosocial work factors on musculoskeletal pain: a prospective study." J Occup Environ Med 43(2): 120-6.
Summary
This is a follow up study of 721 automobile garage workers, which examined the effects of psychological demands, decision authority, social support, and management support on the occurrence of neck pain, LBP, and musculoskeletal pain. Questionnaires were distributed at baseline and after 1 year.
Musculoskeletal pains were common among the participants. Regarding LBP the researchers found significant positive associations after adjusting for age, gender and musculoskeletal pain at baseline, between LBP and:
- Decision authority;
- Management support; and
- Physical work environment.
Linton SL. “Occupational Psychological Factors Increase the Risk for Back Pain: A systematic Review.” Journal of Occupational Rehabilitation 2001:11 (1);53-66
Summary
This study reviews 21 articles (published between 1985 and 2000 and drawn from Medline, Psychinfo and a Scandinavian database in occupational medicine) concerning the role of psychological workplace factors on low back pain (LBP).
Of these articles:
- 14 looked at job satisfaction, and 13 indicated that low job satisfaction was linked to future LBP.
- Six looked at monotonous work and 4 linked monotonous work to future LBP.
- Six looked at social relationships with supervisors and /or workmates and 5 showed that a bad relationship at work was linked to future LBP.
- Three looked at perceived demands/load and all three reported a significant relationship with LBP.
- One looked closely at work content and a few other studies mentioned content, but no conclusions could be drawn.
- Two looked at control and both reported that it had a significant connection with LBP.
- Three looked at pace, of which two found a significant connection with LBP.
- Three looked at self-reported stress. Although each study measured stress differently, all reported a significant relation with LBP.
- Three looked at perceived ability to work and all reported a significant relation with LBP.
- Two looked at the belief that work is dangerous, and both studies found an association between such beliefs and back pain.
- Two looked at emotional effort and both found that it had a relationship with back pain.
In conclusion, strong (but varying) evidence was found for six psychological risk factors and back pain:
- Job satisfaction
- Monotonous work
- Work relations
- Work demands
- Stress
- Perceived ability to work.
Davis KG, Heaney CA. The relationship between psychosocial work characteristics and low back pain: underlying methodological issues. Clinical Biomechanics 15 (2000) 389-406
Summary
This review study focussed on 66 articles (from Medline, Institute for Scientific Information and Psychinfo; latest year of publication 1999) on the relation between psychosocial work factors and low back pain (LBP).
The researchers examined the methodologies of the articles in question, and argued that inconsistent results could be related to inter-study differences regarding:
- Controlling for confounders;
- The timing of the exposure or outcome; and
- The reliability of measurements used e.g. self-report of exposure or severity of back pain.
- The interaction effect of physical risk factors and psychosocial risk factors was a major methodological concern.
The studies which, according to the researchers, scored highest in terms of methodological criteria showed that job satisfaction and job stress are more consistently and more strongly associated with risk of LBP, than are psychosocial work characteristics themselves.
The researchers advise that the relationship between work characteristics (both psychosocial and physical) and job satisfaction requires further exploration. In order to be effective, future studies will also need to address the methodological issues raised above.
Background information to the “Study of Work Causation Literature on back pain”
By Frederieke Schaafsma December 2008/ January 2009
Aim:
To provide up-to-date information on available studies on the etiology of work-related back-disorders based on a search in PubMed (Medline) in November 2008.
Methods:
We performed a search in Medline, using PubMed. The search strategy was based on two studies by Schaafsma 2006 (Am J Industrial Med) and Mattioli 2008 (submitted):
Occupational diseases (mesh) or occupational exposure (mesh) or occupational health (mesh) or occupational medicine (mesh) or occupational risk (tw) or occupational hazard (tw) or work-related or working environment (tw) and name-of- the disease
We used the term back in combination with those terms mentioned above, and used a clinical query filter on etiology (sensitive search) and limited down to English articles on adults, and published last 10 years.
((("Occupational Diseases"[Mesh] OR "Occupational Exposure"[Mesh]) OR "Occupational Health"[Mesh]) OR "Occupational Medicine"[Mesh] OR "occupational risk" OR "occupational hazard" OR work-related OR "working environment") AND ((“Low Back Pain”[MeSH] OR “Back Pain”[MeSH]) AND (risk*[Title/Abstract] OR risk*[MeSH:noexp] OR risk *[MeSH:noexp] OR cohort studies [MeSH Terms] OR group*[Text Word]))
Results : 1073 hits
(("Occupational Diseases"[Mesh] OR "Occupational Exposure"[Mesh]) OR "Occupational Health"[Mesh]) OR "Occupational Medicine"[Mesh] OR "occupational risk" OR "occupational hazard" OR work-related OR "working environment") AND ((“Low Back Pain”[MeSH] OR “Back Pain”[MeSH]) AND systematic [sb])
Results : 74 hits
After going through titles and abstracts and limiting to English and adults 63 articles were selected to give an overview of existing up-to-date evidence on work causation and back disorders. Going through references from these articles and using the related articles button in Medline gave us another 20 articles that were considered relevant to include for this overview. After a closer look, 47 articles on work related low back pain were summarised for this project. In addition, a few articles on personal factors in relation to workers with low back pain are included as well, although the search strategy did not specifically search for these articles.
Because back disorders are so prevalent and the amount of literature that have described possible associations between physical and psychosocial occupational factors, we tried to select those articles that gave either a good overview, using especially systematic reviews, and those studies that highlighted other aspects or specific causes that were not described in the reviews. For this we used cohort studies, case-control studies and cross-sectional studies (national surveys). We used only one or two narrative reviews. Narrative reviews are considered of low evidence following the guidelines of Evidence-Based Medicine, however, they sometimes provide good and comprehensive back ground documents.
Furthermore, we picked out those articles that described the relation between back problems and a specific occupation. In general, the most recent article had our preference above those that were published more then 10 years ago. We added one chapter of a document by NIOSH “A Critical Review of Epidemiologic Evidence for Work-Related Musculoskeletal Disorders of the Neck, Upper Extremity, and Low Back” from 1997 because it gives a good overview of published knowledge on this topic until 1997.
Furthermore, we separately refer to a criteria document on work relatedness of low back pain by Dutch researchers. This is an important document for physicians and other professionals who are interested in determining possible work relatedness of back pain.
We divided the retrieved articles in the following categories:
- back disorders and a combination of risk factors from occupations
-
back disorders and physical risk factors from occupations
- whole body vibrations
- heavy physical work load
- sitting at work
- back disorders and psychosocial risk factors from occupations
- back disorders and specific occupations
- back disorders and personal factors