As part of the international CUPID investigation, we compared physical and psychosocial risk factors for musculoskeletal disorders among nurses in Brazil and Italy. Using questionnaires, we collected information on musculoskeletal disorders and potential risk factors from 751 nurses employed in public hospitals. By fitting country specific multiple logistic regression models, we investigated the association of stressful physical activities and psychosocial characteristics with site-specific and multisite pain, and associated sickness absence. We found no clear relationship between low back pain and occupational lifting, but neck and shoulder pain were more common among nurses who reported prolonged work with the arms in an elevated position. After adjustment for potential confounding variables, pain in the low back, neck and shoulder, multisite pain, and sickness absence were all associated with somatizing tendency in both countries. Our findings support a role of somatizing tendency in predisposing to musculoskeletal disorders, acting as an important mediator of the individual response to triggering exposures, such as workload.

Background

Pain in the neck and shoulder has been linked with various psychosocial risk factors, as well as with occupational physical activities. However, most studies to date have been cross-sectional, making it difficult to exclude reverse causation. Moreover, they have been carried out largely in northern Europe, and the relationship to psychosocial factors might be different in other cultural environments.

Methods

To explore causes of neck/shoulder pain, we carried out a longitudinal study in Iranian nurses and office workers. Participants (n  = 383) completed a baseline questionnaire about neck/shoulder pain in the past month and possible risk factors, and were again asked about pain 12 months later. Associations with pain at follow-up were explored by Poisson regression and summarised by prevalence rate ratios (PRRs).

Results

After adjustment for other risk factors, new pain at follow-up was more frequent in office workers than nurses (PRR 1.9, 95%CI 1.3–2.8), among those with worst mental health (PRR 1.8, 95%CI 1.0–3.0), in those who reported incentives from piecework or bonuses (PRR1.4, 95%CI 1.0–2.0), and in those reporting job dissatisfaction (PRR 1.5, 95%CI 1.0–2.1). The strongest predictor of pain persistence was somatising tendency.

Conclusions

Our findings are consistent with a hazard of neck/shoulder pain from prolonged use of computer keyboards, although it is possible that the association is modified by health beliefs and expectations. They also indicate that the association of low mood with neck/shoulder pain extends to non-European populations, and is not entirely attributable to reverse causation. Psychosocial aspects of work appeared to have relatively weak impact.

Background

Factors influencing work-related musculoskeletal disorders might differ in developing and developed countries.

Aims

To assess the prevalence and determinants of musculoskeletal pain in four occupational populations in Sri Lanka

Methods

As part of the international CUPID study, samples of postal workers, sewing machinists, nurses and computer operators were interviewed about pain in the past month at each of six anatomical sites, and about possible physical and psychosocial risk factors. Associations with prevalent pain were assessed by binomial regression.

Results

Analysis was based on 852 participants (response rate 86%). Overall, the lower back was the most common site of pain, with one-month prevalence ranging from 12% in computer operators to 30% in nurses. Postal workers had the highest prevalence of shoulder pain (23%), but pain in the wrist/hand was relatively uncommon in all four occupational groups (prevalence rates from 8% to 9%). Low mood and tendency to somatise were each consistently associated with pain at all six sites. After adjustment for psychosocial risk factors, there was a higher rate of low back pain in nurses and postal workers than computer operators, a higher rate of shoulder pain in postal workers relative to other occupations, and a relatively low rate of knee pain in computer operators.

Conclusion

Rates of regional pain, especially at the wrist/hand, were lower than have been reported in western countries. As elsewhere, pain was strongly associated with low mood and somatising tendency. Differences in patterns of pain by occupation may reflect differences in physical activities.

Objective

Experts disagree about the optimal classification of upper limb disorders (ULDs). To explore whether differential response to treatments offers a basis for choosing between case definitions, we analysed previously published research.

Methods

We screened 183 randomised controlled trials (RCTs) of treatments for ULDs, identified from the bibliographies of 10 Cochrane reviews, four other systematic reviews, and a search in Medline, Embase, and Google Scholar to June 2010. From these, we selected RCTs which allowed estimates of benefit (expressed as relative risks (RRs)) for >1 case definition to be compared when other variables (treatment, comparison group, follow-up time, outcome measure) were effectively held constant. Comparisons of RRs for paired case definitions were summarised by their ratios, with the RR for the simpler and broader definition as the denominator.

Result

Two RCT reports allowed within-trial comparison of RRs and thirteen others allowed between-trial comparisons. Together these provided 17 ratios of RRs (five for shoulder treatments, 12 for elbow treatments, none for wrist/hand treatments). The median ratio of RRs was 1.0 (range 0.3 to 1.7; interquartile range 0.6 to 1.3).

Conclusion

Although the evidence base is limited, our findings suggest that for musculoskeletal disorders of the shoulder and elbow, clinicians in primary care will often do best to apply simpler and broader case definitions. Researchers should routinely publish secondary analyses for subgroups of patients by different diagnostic features at trial entry, to expand the evidence base on optimal case definitions for patient management.

Introduction

National analyses of mortality in England and Wales have repeatedly shown excess deaths from pneumonia in welders. During 1979-1990 the excess was attributable largely to deaths from lobar pneumonia and pneumonias other than bronchopneumonia, limited to working-aged men, and apparent in other metal fume-exposed occupations. We assessed findings for 1991-2000 and compared the mortality pattern with that from asthma in occupations exposed to known respiratory sensitizers.

Methods

The Office of National Statistics supplied data on deaths by underlying cause among men aged 16-74 years in England and Wales during 1991-2000, including age and last held occupation. We abstracted data on pneumonia for occupations with exposure to metal fume and on asthma for occupations commonly reported to surveillance schemes as at risk of occupational asthma. We estimated expected numbers of deaths by applying age-specific proportions of deaths by cause in the population to the total deaths by age in each occupational group. Observed and expected numbers were compared for each cause of death.

Results

Among working-aged men in metal fume-exposed occupations we found excesses of mortality from pneumococcal and lobar pneumonia (54 deaths vs. 27.3 expected) and from pneumonias other than bronchopneumonia (71 vs. 52.4), but no excess from these causes at older ages, or from bronchopneumonia at any age. The attributable mortality from metal fume (45.3 excess deaths) compared with an estimated 62.6 deaths from occupational asthma.

Conclusion

Exposure to metal fume is a material cause of occupational mortality. The hazard deserves far more attention than it presently receives.

Background

Experts disagree about the optimal classification of upper limb disorders (ULDs). To explore whether differences in associations with occupational risk factors offer a basis for choosing between case definitions in aetiological research and surveillance, we analysed previously published research.

Methods

Eligible reports (those with estimates of relative risk (RR) for >1 case definition relative to identical exposures were identified from systematic reviews of ULD and occupation and by hand-searching five peer-review journals published between January 1990 and June 2010. We abstracted details by anatomical site of the case and exposure definitions employed and paired estimates of RR, for alternative case definitions with identical occupational exposures. Pairs of case definitions were typically nested, a stricter definition being a subset of a simpler version. Differences in RR between paired definitions were expressed as the ratio of RRs, using that for the simpler definition as the denominator.

Results

We found 21 reports, yielding 320 pairs of RRs (82, 75 and 163 respectively at the shoulder, elbow, and distal arm). Ratios of RRs were frequently ≤1 (46%), the median ratio overall and by anatomical site being close to unity. In only 2% of comparisons did ratios reach ≥4.

Conclusion

Complex ULD case definitions (e.g. involving physical signs, more specific symptom patterns, and investigations) yield similar associations with occupational risk factors to those using simpler definitions. Thus, in population-based aetiological research and surveillance, simple case definitions should normally suffice. Data on risk factors can justifiably be pooled in meta-analyses, despite differences in case definition.

Objectives

To explore the relationship between occupational exposures and lateral and medial epicondylitis and the effect of epicondylitis on sickness absence in a population sample of working aged adults.

Methods

This was a cross-sectional study of 9696 randomly selected adults aged 25-64 years involving a screening questionnaire and standardised physical examination. Age- and sex-specific prevalence rates of epicondylitis were estimated and associations with occupational risk factors explored.

Results

Among 6038 respondents, 636 (11%) reported elbow pain in the last week. 0.7% of those surveyed were diagnosed with lateral epicondylitis and 0.6% with medial epicondylitis. Lateral epicondylitis was associated with manual work (OR 4.0, 95% CI 1.9-8.4). In multivariate analyses, repetitive bending/straightening elbow > 1 hour day was independently associated with lateral (OR 2.5, 95% CI 1.2-5.5) and medial epicondylitis (OR 5.1, 95% CI 1.8-14.3). 5% of adults with epicondylitis took sickness absence because of their elbow symptoms in the past 12 months (median 29 days).

Conclusions

Repetitive exposure to bending/straightening the elbow was a significant risk factor for medial and lateral epicondylitis. Epicondylitis is associated with prolonged sickness absence in 5% of affected working-aged adults.

This systematic review assesses the effectiveness of interventions in community and workplace settings to reduce sickness absence and job loss in workers with musculoskeletal disorders (MSDs). Relevant studies (randomised controlled trials (RCTs) and cohort studies published since 1990) were identified by screening citations in 35 earlier systematic reviews and from searches of Medline and Embase to April 2010. Among 42 studies (54 reports) including 34 RCTs, 27 assessed return to work, 21 duration of sickness absence, and five job loss. Interventions included exercise therapy, behavioural change techniques, workplace adaptations and provision of additional services. Studies were typically small (median sample size 107 (inter-quartile range (IQR) 77 to 148) and limited in quality. Most interventions were reported as beneficial: the median relative risk (RR) for return to work was 1.21 (IQR 1.00 – 1.60) and that for avoiding MSD-related job loss, 1.25 (IQR 1.06-1.71); the median reduction in sickness absence was 1.11 (IQR 0.32 to 3.20) days/month. However, effects were smaller in the larger and better quality studies, suggesting publication bias. No intervention was clearly superior to others, although effort-intensive interventions were less effective than simple ones. No cost-benefit analyses established statistically significant net economic benefits. Given that benefits are small and of doubtful cost-effectiveness, employers’ practice should be guided by their value judgements about the uncertainties. Expensive interventions should be implemented only with rigorous cost-benefit evaluation planned from the outset. Future research should focus on the cost-effectiveness of simple low cost interventions, and further explore impacts on job retention.

summary

The epidemiology of microbial keratitis has been investigated in several studies by analysis of organisms cultured from corneal scrapes. However, a comparison of the frequency of different organisms causing keratitis in different parts of the world is lacking. We present a review incorporating an analysis of data from studies worldwide. The data provide a comparison of the frequency of culture-positive organisms found in different parts of the world.

The highest proportion of bacterial corneal ulcers was reported in studies from North America, Australia, the Netherlands and Singapore. The highest proportion of staphylococcal ulcers was found in a study from Paraguay whilst the highest proportion of pseudomonas ulcers was reported in a study from Bangkok. The highest proportions of fungal infections were found in studies from India and Nepal. Possible explanations for these observed geographic variations are discussed.

Background

The CUPID (Cultural and Psychosocial Influences on Disability) study was established to explore the hypothesis that common musculoskeletal disorders (MSDs) and associated disability are importantly influenced by culturally determined health beliefs and expectations. This paper describes the methods of data collection and various characteristics of the study sample.

Methods/Principal Findings

A standardised questionnaire covering musculoskeletal symptoms, disability and potential risk factors, was used to collect information from 47 samples of nurses, office workers, and other (mostly manual) workers in 18 countries from six continents. In addition, local investigators provided data on economic aspects of employment for each occupational group. Participation exceeded 80% in 33 of the 47 occupational groups, and after pre-specified exclusions, analysis was based on 12,426 subjects (92 to 1018 per occupational group). As expected, there was high usage of computer keyboards by office workers, while nurses had the highest prevalence of heavy manual lifting in all but one country. There was substantial heterogeneity between occupational groups in economic and psychosocial aspects of work; three- to five-fold variation in awareness of someone outside work with musculoskeletal pain; and more than ten-fold variation in the prevalence of adverse health beliefs about back and arm pain, and in awareness of terms such as “repetitive strain injury” (RSI).

Conclusions/Significance

The large differences in psychosocial risk factors (including knowledge and beliefs about MSDs) between occupational groups should allow the study hypothesis to be addressed effectively.

We hypothesised that the relative importance of physical and psychological risk factors for mechanical low back pain (LBP) might differ importantly according to whether there is underlying spinal pathology, psychological risk factors being more common in patients without demonstrable pathology. If so, epidemiological studies of LBP could benefit from tighter case definitions. To test the hypothesis, we used data from an earlier case-control study on patients with mechanical LBP who had undergone magnetic resonance imaging (MRI) of the lumbosacral spine. MRI scans were classified for the presence of high-intensity zone (HIZ), disc degeneration, disc herniation, and nerve root displacement/compression. Information about symptoms and risk factors was elicited by postal questionnaire. Logistic regression was used to assess associations of MRI abnormalities with symptoms and risk factors, which were characterised by odds ratios (ORs) and 95% confidence intervals (CIs). Among 354 patients (52% response), 306 (86.4%) had at least 1, and 63 (17.8%) had all 4 of all MRI abnormalities. Radiation of pain below the knee (280 patients) and weakness or numbness below the knee (257 patients) were both associated with nerve root deviation/compression (OR 2.5, 95% CI 1.4 to 4.5; and OR 1.8, 95% CI 1.1 to 3.1, respectively). However, we found no evidence for the hypothesised differences in risk factors between patients with and without demonstrable spinal pathology. This suggests that when researching the causes and primary prevention of mechanical LBP, there may be little value in distinguishing between cases according to the presence or absence of the more common forms of potentially underlying spinal pathology.

Background

National initiatives to prevent and/or manage sickness absence require a database from which trends can be monitored.

Aims

To evaluate the information provided by surveillance schemes and publicly available datasets on sickness absence nationally from musculoskeletal disorders (MSDs).

Methods

A grey literature search was undertaken using the search engine Google, supplemented by leads from consultees from academia, industry, employers, lay interest groups and government. We abstracted data on the outcomes and populations covered, and made quantitative estimates of MSD-related sickness absence, overall and, where distinguishable, by sub-diagnosis. The coverage and limitations of each source were evaluated.

Results

Sources included the Labour Force Survey (LFS) and its Self-reported Work-related Illness survey module; the THOR-GP surveillance scheme; surveys by national and local government; surveys by employers’ organisations; and a database of benefit statistics. Each highlighted MSDs as a leading cause of sickness absence. Data limitations varied by source, but typically included lack of diagnostic detail and restriction of focus to selected subgroups (e.g. work-ascribed or benefit-awarded cases, specific employment sectors). Additionally, some surveys had very low response rates, were completed only by proxy respondents, or ranked only the perceived importance of MSD-related sickness absence, rather than measuring it.

Conclusions

National statistics on MSD-related sickness absence are piecemeal and incomplete. This limits capacity to plan and monitor national policies in an important area of public health. Simple low-cost additions to the LFS would improve the situation.

Background

A recent systematic review and meta-analysis suggested that occupational exposure to endotoxins protects against lung cancer. To explore this hypothesis further the follow-up of mortality of a cohort of 3551 workers, who were employed in the British cotton industry during 1966-1971, was extended by 23 years.

Methods

Subjects had originally been recruited to a survey of respiratory disease, which collected information about occupation and smoking habits. Cumulative exposures to endotoxin were estimated from data on endotoxin levels by work areas in cotton mills. Risks of lung cancer were estimated using survival modelling.

Results

During follow-up, 2,018 deaths were recorded before age 90, including 128 deaths from lung cancer. After adjustment for smoking, hazard ratios (95% confidence intervals) for cumulative endotoxin exposures of ≤30,000, >30,000 and ≤200,000, >200,000 and ≤400,000, >400,000 and ≤600,000 and > 600,000 Endotoxin Units m−3 years were 1, 0.8 (0.5 to 1.6), 0.7 (0.4 to 1.3), 0.6 (0.3 to 1.0) and 0.5 (0.3 to 0.9) respectively (P for trend = 0.005).

Conclusions

Our findings strengthen the evidence that occupational exposure to endotoxins protects against lung cancer, and suggests that the effect depends on cumulative dose and persists after exposure ceases.

Summary

Background

It has been argued that in case-control studies, controls should be drawn from the base population that gives rise to the cases. In designing a study of occupational injury and risks arising from long-term illness and prescribed medication, we lacked data on subjects’ occupation, without which employed cases (typically in manual occupations) would be compared with controls from the general population, including the unemployed and a higher proportion of white-collar professions. Collecting the missing data on occupation would be costly. We estimated the potential for bias if the selection rule were ignored.

Methods

We obtained published estimates of the frequencies of several exposures of interest (diabetes, mental health problems, asthma, coronary heart disease) in the general population, and of the relative risks of these diseases in unemployed vs. employed individuals and in manual vs. non-manual occupations. From these we computed the degree of over- or underestimation of exposure frequencies and exposure odds ratios if controls were selected from the general population.

Results

The potential bias in the odds ratio was estimated as likely to fall between an underestimation of 14% and an overestimation of 36.7% (95th centiles). In fewer than 6% of simulations did the error exceed 30%, and in none did it reach 50%.

Conclusions

For the purposes of this study, in which we were interested only in substantial increases in risk, the potential for selection bias was judged acceptable. The rule that controls should come from the same base population as cases can justifiably be broken, at least in some circumstances.

Background

National analyses of occupational mortality provide information on the most severe diseases and injuries caused by work, enabling preventive actions to be targeted and evaluated. To explore time trends in deaths attributable to work in England and Wales, and identify priorities for prevention, we conducted a proportional analysis of mortality by occupation over a 22-year period.

Methods

Analysis was based on the 93% of deaths in men aged 20-74 years during 1979-80 and 1982-2000 with a recorded occupation. Proportional mortality ratios, standardised for age and social class, were calculated for pre-specified combinations of occupation and cause of death, for which excess mortality could reasonably be attributed to work. Differences between observed and expected numbers of deaths by cause and occupation were expressed as annual excess death rates, and as fractions of all deaths in relevant occupations.

Results

Mortality attributable to work declined substantially over the period of study, with total excess death rates of 733.2 per year during 1979-1990 and 471.7 per year during 1991-2000. The largest contributing hazards were chronic obstructive pulmonary disease and pneumoconiosis in coal miners, pleural cancer from asbestos, and motor vehicle accidents in lorry drivers. In contrast to most other hazards, there was no clear decline in excess mortality attributable to asbestos, or in deaths from sino-nasal cancer associated with exposure to wood dust. Risk of work-related mortality was particularly high in coal miners and aircraft flight deck officers among whom approximately 4% of deaths were attributable to occupation.

Conclusions

The overall decline in mortality attributable to work is likely to reflect reduced employment in more hazardous occupations, as well as improvements in working conditions. It is imperative to ensure that occupational exposures to asbestos and wood dust are now adequately controlled. Further research is needed on accidents involving lorries with the aim of developing more effective strategies for the prevention of injury.

Background

Work in commercial fishing is physically demanding and hazardous, but unlike merchant seamen, fishermen are not required to hold a certificate of medical fitness.

Aims

To investigate the case for regulatory medical standards for commercial fishermen, and to identify priorities for the prevention and management of occupational injuries at sea.

Methods

We surveyed a convenience sample of fishermen at three major fishing ports in South-west England, using a standardised, interview-administered questionnaire.

Results

Interviews were completed by 210 (68%) of 307 fishermen approached. Over their careers, 56 subjects (27%) had been returned to shore as an emergency for medical reasons, a rate of 14.6 (95% CI 11.5-18.2) per 1000 man-years. Most emergency evacuations were for acute injuries, and only five were for illness. A few participants suffered from chronic disease that would call into question their fitness to go to sea. Fifty five fishermen had suffered injuries in the past 12 months, including 12 that had caused loss of more than three days from work. Subjects had self-stitched four of 15 reported hand lacerations, while others had been bound with “Gaffer” tape.

Conclusion

Prevention of hand lacerations should be a high priority, with first aid training and equipment for fishing crews to improve their care when prevention fails. No firm conclusions can be drawn about the value of regular medical screening for commercial fishermen, but such screening should be considered a lower priority than accident prevention.

Objectives

Musculoskeletal pain is associated with occupational physical activities and psychosocial risk factors. We evaluated the relative importance of work-related and psychological determinants of the number of anatomical sites affected by musculoskeletal pain in a cross-sectional survey.

Methods

The survey focused on musculoskeletal pain in six body regions (low-back, neck, shoulder, elbow, wrist/hand and knee) among 224 nurses, 200 office workers and 140 postal clerks in Crete (response rate 95%). Information was collected about demographic characteristics, occupational physical load, psychosocial aspects of work, perceptions about causes of pain, mental health, tendency to somatize, and experience of pain in the past 12 months. Poisson regression was used to assess associations of risk factors with the number of painful anatomical sites and interactions were explored using classification and regression trees (CART).

Results

Two-thirds of the study sample reported pain in at least two body sites during the past 12 months, and in 23%, more than three sites were affected. The number of painful anatomical sites was strongly related to both physical load at work and somatizing tendency (with relative risks increased five-fold or more for frequent and disabling multisite pain) , and was also significantly associated with work-related psychosocial factors, and beliefs about work causation. The CART analysis suggested that in the population studied, the leading determinant of the number of painful body sites was somatizing tendency.

Conclusions

In the population studied, pain at multiple anatomical sites is common, and is strongly associated with somatizing tendency, which may have a more important influence on multi-site pain than on pain that is limited to a single anatomical site.

AIms

To identify opportunities for targeted prevention, we explored differences in occupational mortality from diseases and injuries related to alcohol consumption, sexual habits and drug abuse.

Methods

Using data on all deaths among men and women aged 16-74 years in England and Wales during 1991-2000, we derived age- and social class-standardised proportional mortality ratios (PMRs) by occupation for cause of death categories defined a priori as potentially related to alcohol consumption, sexual habits or drug abuse.

Results

The highest mortality from alcohol-related diseases and injuries was observed in publicans and bar staff (both sexes), and in male caterers, cooks and kitchen porters, and seafarers. Male seafarers had significantly elevated PMRs for cirrhosis (179), “other alcohol-related diseases” (275), cancers of the liver (155), oral cavity (275) and pharynx (267), and injury by fall on the stairs (187). PMRs for HIV/AIDS were particularly high in tailors and dressmakers (918, 95%CI 369-1890, in men; 804, 95%CI 219-2060, in women) and male hairdressers (918, 95%CI 717-1160). Most jobs with high mortality from HIV/AIDS also had more deaths than expected from viral hepatitis. Of seven jobs with significantly high PMRs for both drug dependence and accidental poisoning by drugs, four were in the construction industry (male painters and decorators, bricklayers and masons, plasterers, and roofers and glaziers).

Conclusions

Our findings highlight major differences between occupations in mortality from diseases and injuries caused by alcohol, sexual habits and drug abuse. Priorities for preventive action include alcohol-related disorders in male seafarers and drug abuse in construction workers.

Background

An unusual inflammation of the pinna has been reported to occur in some sheep farmers at the time of lambing.

Aims

To explore the prevalence of this disorder and its possible causal associations.

Methods

While on attachment to sheep farms during lambing, veterinary students used a standardised questionnaire to interview a sample of farmers about their work, and about symptoms of skin inflammation in their hands, face and ears.

Results

Interviews were completed by 76 (67%) of the farmers approached. Among 74 farmers who had carried out lambing, three (4%, 95% CI 1% to 11%) had experienced temporally related ear symptoms, all on multiple occasions. No farmers with ear symptoms had ever been involved in calving or farrowing, and no ear symptoms were reported in relation to shearing or dipping sheep. There was also an excess of hand symptoms related to lambing outdoors (24% of those who had done such work) and indoors (also 24%), compared with other farming activities.

Conclusions

Our findings suggest that temporally related ear inflammation occurs in at least 1% of farmers who carry out lambing, but not in association with the other farming activities investigated. Lambing appears to be associated also with hand inflammation, but the pathology may differ from that in the pinna.

Background

Since the early 1990s, rates of incapacity benefit (IB) in Britain for musculoskeletal complaints have declined, and they have been overtaken by mental and behavioural disorders as the main reason for award of IB.

Aims

To explore reasons for this change.

Methods

Using data supplied by the Department for Work and Pensions, we analysed trends in the ratio of new IB awards for mental and behavioural disorders to those for musculoskeletal disorders during 1997-2007 by Government region.

Results

In Great Britain overall, the above ratio more than doubled over the study period, as a consequence of falling numbers of new awards for musculoskeletal disorders. The extent to which the ratio increased was smallest in London (50%) and South-East England (56%), and was progressively larger in more northerly regions (>150% in North-East England and Scotland).

Conclusions

The differences in trends between regions seem too large to be explained by differential changes in working conditions, patterns of employment, or the rigour with which claims were assessed. An alternative explanation could be that the main driver for the trends has been culturally determined changes in health beliefs and expectations, and that these cultural changes began in London and the South-East, only later spreading to other parts of Britain.

Background

It is possible that clinical outcome of low back pain (LBP) differs according to the presence or absence of spinal abnormalities on magnetic resonance imaging (MRI), in which case there could be value in using MRI findings to refine case definition of LBP in epidemiological research. We therefore conducted a longitudinal study to explore whether spinal abnormalities on MRI for LBP predict prognosis after 18 months.

Methods

A consecutive series of patients aged 20-64 years, who were investigated by MRI because of mechanical LBP (median duration of current episode 16.2 months), were identified from three radiology departments, and those who agreed completed self-administered questionnaires at baseline and after a mean follow-up period of 18.5 months (a mean of 22.2 months from MRI investigation). MRI scans were assessed blind to other clinical information, according to a standardised protocol. Associations of baseline MRI findings with pain and disability at follow-up, adjusted for treatment and for other potentially confounding variables, were assessed by Poisson regression and summarised by prevalence ratios (PRs) with their 95% confidence intervals (CIs).

Results

Questionnaires were completed by 240 (74%) of the patients who had agreed to be followed up. Among these 111 men and 129 women, 175 (73%) reported LBP in the past four weeks, 89 (37%) frequent LBP, and 72 (30%) disabling LBP. In patients with initial disc degeneration there was an increased risk of frequent (PR 1.3, 95%CI 1.0-1.9) and disabling LBP (PR 1.7, 95%CI 1.1-2.5) at follow-up. No other associations were found between MRI abnormalities and subsequent outcome.

Conclusions

Our findings suggest that the MRI abnormalities examined are not major predictors of outcome in patients with LBP. They give no support to the use of MRI findings as a way of refining case definition for LBP in epidemiological research.