We assessed the evidence relating pre-term delivery (PTD), low birthweight, small for gestational age (SGA), pre-eclampsia and gestational hypertension to five occupational exposures (working hours, shift work, lifting, standing and physical workload). We conducted a systematic search in MEDLINE and EMBASE (1966–2011), updating a previous search with a further six years of observations.
As before, combinations of keywords and MeSH terms were used. Each relevant paper was assessed for completeness of reporting and potential for important bias or confounding, and its effect estimates abstracted. Where similar definitions of exposure and outcome existed we calculated pooled estimates of relative risk in meta-analysis.
Analysis was based on 86 reports (32 cohort investigations, 57 with usable data on PTD, 54 on birthweight and 11 on pre-eclampsia/gestational hypertension); 33 reports were new to this review. For PTD, findings across a substantial evidence base were generally consistent, effectively ruling out large effects (e.g. RR>1.2). Larger and higher quality studies were less positive, while meta-estimates of risk were smaller than previously and best estimates pointed to modest or null effects (RR 1.04 to 1.18). For SGA, the position was similar but meta-estimates were even closer to the null (eight of nine RRs ≤ 1.07). For pre-eclampsia/gestational hypertension the evidence base remains insufficient.
The balance of evidence is against large effects for the associations investigated. As the evidence base has grown, estimates of risk in relation to these outcomes have become smaller.
pregnancy; occupation; review; meta-analysis
To explore definitions for multi-site pain, and compare associations with risk factors for different patterns of musculoskeletal pain, we analysed cross-sectional data from the Cultural and Psychosocial Influences on Disability (CUPID) study. The study sample comprised 12,410 adults aged 20-59 years from 47 occupational groups in 18 countries. A standardised questionnaire was used to collect information about pain in the past month at each of 10 anatomical sites, and about potential risk factors. Associations with pain outcomes were assessed by Poisson regression, and characterised by prevalence rate ratios (PRRs). Extensive pain, affecting 6-10 anatomical sites, was reported much more frequently than would be expected if the occurrence of pain at each site were independent (674 participants v 41.9 expected). In comparison with pain involving only 1-3 sites, it showed much stronger associations (relative to no pain) with risk factors such as female sex (PRR 1.6 v 1.1), older age (PRR 2.6 v 1.1), somatising tendency (PRR 4.6 v 1.3) and exposure to multiple physically stressing occupational activities (PRR 5.0 v 1.4). After adjustment for number of sites with pain, these risk factors showed no additional association with a distribution of pain that was widespread according to the frequently used American College of Rheumatology (ACR) criteria. Our analysis supports the classification of pain at multiple anatomical sites simply by the number of sites affected, and suggests that extensive pain differs importantly in its associations with risk factors from pain that is limited to only a small number of anatomical sites.
In a large cross-sectional survey, pain affecting 6–10 anatomical sites showed substantially different associations with risk factors from pain limited to 1–3 sites.
To explore definitions for multisite pain, and compare associations with risk factors for different patterns of musculoskeletal pain, we analysed cross-sectional data from the Cultural and Psychosocial Influences on Disability (CUPID) study. The study sample comprised 12,410 adults aged 20–59 years from 47 occupational groups in 18 countries. A standardised questionnaire was used to collect information about pain in the past month at each of 10 anatomical sites, and about potential risk factors. Associations with pain outcomes were assessed by Poisson regression, and characterised by prevalence rate ratios (PRRs). Extensive pain, affecting 6–10 anatomical sites, was reported much more frequently than would be expected if the occurrence of pain at each site were independent (674 participants vs 41.9 expected). In comparison with pain involving only 1–3 sites, it showed much stronger associations (relative to no pain) with risk factors such as female sex (PRR 1.6 vs 1.1), older age (PRR 2.6 vs 1.1), somatising tendency (PRR 4.6 vs 1.3), and exposure to multiple physically stressing occupational activities (PRR 5.0 vs 1.4). After adjustment for number of sites with pain, these risk factors showed no additional association with a distribution of pain that was widespread according to the frequently used American College of Rheumatology criteria. Our analysis supports the classification of pain at multiple anatomical sites simply by the number of sites affected, and suggests that extensive pain differs importantly in its associations with risk factors from pain that is limited to only a small number of anatomical sites.
Pain; Multisite; Widespread; Definition; Risk factors
To explore whether risk factors for neurophysiologically confirmed carpal tunnel syndrome (CTS) differ from those for sensory symptoms with normal median nerve conduction, and to test the validity and practical utility of a proposed definition for impaired median nerve conduction, we carried out a case–control study of patients referred for investigation of suspected CTS.
We compared 475 patients with neurophysiological abnormality (NP+ve) according to the definition, 409 patients investigated for CTS but classed as negative on neurophysiological testing (NP-ve), and 799 controls. Exposures to risk factors were ascertained by self-administered questionnaire. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were estimated by logistic regression.
NP+ve disease was associated with obesity, use of vibratory tools, repetitive movement of the wrist or fingers, poor mental health and workplace psychosocial stressors. NP-ve illness was also related to poor mental health and occupational psychosocial stressors, but differed from NP+ve disease in showing associations also with prolonged use of computer keyboards and tendency to somatise, and no relation to obesity. In direct comparison of NP+ve and NP-ve patients (the latter being taken as the reference category), the most notable differences were for obesity (OR 2.7, 95 % CI 1.9-3.9), somatising tendency (OR 0.6, 95% CI 0.4-0.9), diabetes (OR 1.6, 95% CI 0.9-3.1) and work with vibratory tools (OR 1.4, 95% CI 0.9-2.2).
When viewed in the context of earlier research, our findings suggest that obesity, diabetes, use of hand-held vibratory tools, and repeated forceful movements of the wrist and hand are causes of impaired median nerve function. In addition, sensory symptoms in the hand, whether from identifiable pathology or non-specific in origin, may be rendered more prominent and distressing by hand activity, low mood, tendency to somatise, and psychosocial stressors at work. These differences in associations with risk factors support the validity of our definition of impaired median nerve conduction.
Carpal tunnel syndrome; Nerve conduction; Case–control; Obesity; Vibration; Occupation; Psychosocial; Somatising tendency; Upper limb disorders
We have previously proposed that sensory nerve conduction (SNC) in the median nerve should be classed as abnormal when the difference between conduction velocities in the little and index fingers is > 8 m/s. In a prospective longitudinal study, we investigated whether this case definition distinguished patients who were more likely to benefit from surgical treatment.
We followed up 394 patients (response rate 56%), who were investigated by a neurophysiology service for suspected carpal tunnel syndrome. Information about symptoms, treatment and other possible determinants of outcome was obtained through questionnaires at baseline and after follow-up for a mean of 19.2 months. Analysis focused on 656 hands with numbness, tingling or pain at baseline. Associations of surgical treatment with resolution of symptoms were assessed by Poisson regression, and summarised by prevalence rate ratios (PRRs) and associated 95% confidence intervals (95% CIs).
During follow-up, 154 hands (23%) were treated surgically, and sensory symptoms resolved in 241 hands (37%). In hands with abnormal median SNC, surgery was associated with resolution of numbness, tingling and pain (PRR 1.5, 95% CI 1.0-2.2), and of numbness and tingling specifically (PRR 1.8, 95% CI 1.3-2.6). In contrast, no association was apparent for either outcome when median SNC was classed as normal.
Our definition of abnormal median SNC distinguished a subset of patients who appeared to benefit from surgical treatment. This predictive capacity gives further support to its validity as a diagnostic criterion in epidemiological research.
Carpal tunnel syndrome; Neurophysiology; Case definition; Validity; Surgery; Outcome
To inform the clinical management of patients with suspected carpal tunnel syndrome (CTS) and case definition for CTS in epidemiological research, we explored the relation of symptoms and signs to sensory nerve conduction (SNC) measurements.
Patients aged 20–64 years who were referred to a neurophysiology service for investigation of suspected CTS, completed a symptom questionnaire (including hand diagrams) and physical examination (including Tinel’s and Phalen’s tests). Differences in SNC velocity between the little and index finger were compared according to the anatomical distribution of symptoms in the hand and findings on physical examination.
Analysis was based on 1806 hands in 908 patients (response rate 73%). In hands with numbness or tingling but negative on both Tinel’s and Phalen’s tests, the mean difference in SNC velocities was no higher than in hands with no numbness or tingling. The largest differences in SNC velocities occurred in hands with extensive numbness or tingling in the median nerve sensory distribution and both Tinel’s and Phalen’s tests positive (mean 13.8, 95% confidence interval (CI) 12.6-15.0 m/s). Hand pain and thumb weakness were unrelated to SNC velocity.
Our findings suggest that in the absence of other objective evidence of median nerve dysfunction, there is little value in referring patients of working age with suspected CTS for nerve conduction studies if they are negative on both Tinel’s and Phalen’s tests. Alternative case definitions for CTS in epidemiological research are proposed according to the extent of diagnostic information available and the relative importance of sensitivity and specificity.
Epidemiology; Evidence-based medicine; Hand; Nerve compression syndromes; Wrist
Most pregnant women are exposed to some physical activity at work. This guidance is aimed at doctors advising healthy women with uncomplicated singleton pregnancies about the risks arising from five common workplace exposures (prolonged working hours, shift work, lifting, standing and heavy physical workload). The adverse outcomes considered are: miscarriage, preterm delivery, small-for-gestational age, low birthweight, pre-eclampsia and gestational hypertension. Systematic review of the literature indicates that these exposures are unlikely to carry much of an increased risk for any of the outcomes, since small apparent effects may be explicable in terms of chance, bias, or confounding, while larger and better studies yield lower estimated risks than smaller and weaker studies.
In general, patients may be reassured that such work is associated with little, if any, adverse effect on pregnancy. Moreover, moderate physical exercise is thought to be healthy in pregnancy and most pregnant women undertake some physical work at home. The guidelines provide risk estimates and advice on counselling.
To explore occupational and psychological risk factors for the incidence and persistence of multi-site musculoskeletal pain.
We conducted a longitudinal investigation of three occupational groups in Crete, Greece. Baseline information was obtained at interview about pain in the past year at each of six anatomical sites, and about possible risk factors for subsequent symptoms. Twelve months later, subjects were re-interviewed about pain at the same anatomical sites in the past month. Pain at two or more sites was classed as multi-site. Associations with new development and persistence of multi-site pain at follow-up were assessed by logistic regression.
Analysis was based on 518 subjects (87% of those originally selected for study). At follow-up, multi-site pain persisted in 217 (62%) of those who had experienced it in the year before baseline, and was newly developed in 27 (17%) of those who had not. Persistence of multi-site pain was significantly related to physical loading at work, somatising tendency and beliefs about work as a cause of musculoskeletal pain, with ORs (95%CIs) for the highest relative to the lowest exposure categories of 2.3 (1.0-5.6), 2.6 (1.5-4.6) and 1.9 (1.1-3.3) respectively. Development of new multi-site pain was most strongly associated with working for ≥ 40 hours per week (OR 5.0, 95%CI 1.1-24.0).
Our findings confirm the importance of both physical loading at work and somatising tendency as risk factors for multi-site pain, and suggest that persistence of pain is also influenced by adverse beliefs about work-causation.
To assess the importance of psychological and culturally-influenced factors as predictors of incidence and persistence of LBP in a Spanish working population.
As part of the international CUPID study, 1105 Spanish nurses and office workers, aged 20-59 years, answered questions at baseline about LBP in the past month and past year, associated disability, occupational lifting, smoking habits, health beliefs, mental health, and distress from common somatic symptoms. At follow-up 12 months later, they were asked again about LBP and associated disability in the past month. Associations with the incidence and persistence of LBP were assessed by log binomial regression, and characterised by prevalence rate ratios (PRRs) with associated 95% confidence intervals (CIs).
971 participants (87.9%) completed follow-up. Among 579 with no LBP at baseline, 22.8% reported LBP at follow-up. After adjustment for sex, age and occupation, development of new LBP was predicted by poor mental health (PRR 1.5, 95%CI 1.0-2.2), somatising tendency (PRR 1.8, 95%CI 1.2-2.7), and presence of LBP for >1 month in the year before baseline (PRR 4.7, 95%CI 3.1-6.9). Among 392 subjects who had LBP at baseline, 59.4% reported persistence at follow-up. Persistence of LBP was associated with presence of symptoms for >1 month in the 12 months before baseline (PRR 1.4, 95%CI 1.2-1.7), and more weakly with somatising tendency, and with adverse beliefs about the work-relatedness and prognosis of LBP
In Spain, as in northern European countries, psychological and culturally-influenced factors have an important role in the development and persistence of LBP.
low back pain; health beliefs; mental health; somatising tendency
Statistics from Labour Force Surveys are widely quoted as evidence for the scale of occupational illness in Europe. However, occupational attribution depends on whether participants believe their health problem is caused or aggravated by work, and personal beliefs may be unreliable. We assessed the potential for error for work-associated arm pain.
We mailed a questionnaire to working-aged adults, randomly chosen from five British general practices. We asked about: occupational activities; mental health; self-rated health; arm pain; and beliefs about its causation. Those in work (n = 1769) were asked about activities likely to cause arm pain, from which we derived a variable for exposure to any ‘arm-straining’ occupational activity. We estimated the relative risk (RR) from arm-straining activity, using a modified Cox model, and derived the population attributable fraction (PAF). We compared the proportion of arm pain cases reporting their symptom as caused or made worse by work with the calculated PAF, overall and for subsets defined by demographic and other characteristics.
Arm pain in the past year was more common in the 1,143 subjects who reported exposure to arm-straining occupational activity (RR 1.2, 95% confidence interval 1.1 to 1.5). In the study sample as a whole, 53.9% of 817 cases reported their arm pain as work-associated, whereas the PAF for arm-straining occupational activity was only 13.9%. The ratio of cases reported as work-related to the calculated attributable number was substantially higher below 50 years (5.4) than at older ages (3.0) and higher in those with worse self-rated and mental health.
Counting people with arm pain which they believe to be work-related can overestimate the number of cases attributable to work substantially. This casts doubt on the validity of a major source of information used by European Governments to evaluate their occupational health strategies.
Large international variation in the prevalence of disabling forearm and low back pain was only partially explained by established personal and socioeconomic risk factors.
To compare the prevalence of disabling low back pain (DLBP) and disabling wrist/hand pain (DWHP) among groups of workers carrying out similar physical activities in different cultural environments, and to explore explanations for observed differences, we conducted a cross-sectional survey in 18 countries. Standardised questionnaires were used to ascertain pain that interfered with everyday activities and exposure to possible risk factors in 12,426 participants from 47 occupational groups (mostly nurses and office workers). Associations with risk factors were assessed by Poisson regression. The 1-month prevalence of DLBP in nurses varied from 9.6% to 42.6%, and that of DWHP in office workers from 2.2% to 31.6%. Rates of disabling pain at the 2 anatomical sites covaried (r = 0.76), but DLBP tended to be relatively more common in nurses and DWHP in office workers. Established risk factors such as occupational physical activities, psychosocial aspects of work, and tendency to somatise were confirmed, and associations were found also with adverse health beliefs and group awareness of people outside work with musculoskeletal pain. However, after allowance for these risk factors, an up-to 8-fold difference in prevalence remained. Systems of compensation for work-related illness and financial support for health-related incapacity for work appeared to have little influence on the occurrence of symptoms. Our findings indicate large international variation in the prevalence of disabling forearm and back pain among occupational groups carrying out similar tasks, which is only partially explained by the personal and socioeconomic risk factors that were analysed.
Low back; Forearm; Pain; International; Socioeconomic; Psychosocial
The aim of this study was to investigate whether whole-body vibration (WBV) is associated with prolapsed lumbar intervertebral disc (PID) and nerve root entrapment among patients with low-back pain (LBP) undergoing magnetic resonance imaging (MRI).
A consecutive series of patients referred for lumbar MRI because of LBP were compared with controls X-rayed for other reasons. Subjects were questioned about occupational activities loading the spine, psychosocial factors, driving, personal characteristics, mental health, and certain beliefs about LBP. Exposure to WBV was assessed by six measures, including weekly duration of professional driving, hours driven at a spell, and current 8-hour daily equivalent root-mean-square acceleration A(8). Cases were sub-classified according to whether or not PID/nerve root entrapment was present. Associations with WBV were examined separately for cases with and without these MRI findings, with adjustment for age, sex, and other potential confounders.
Altogether, 237 cases and 820 controls were studied, including 183 professional drivers and 176 cases with PID and/or nerve root entrapment. Risks associated with WBV tended to be lower for LBP with PID/nerve root entrapment but somewhat higher for risks of LBP without these abnormalities. However, associations with the six metrics of exposure were all weak and not statistically significant. Neither exposure–response relationships nor increased risk of PID/nerve root entrapment from professional driving or exposure at an A(8) above the European Union daily exposure action level were found.
WBV may be a cause of LBP but it was not associated with PID or nerve root entrapment in this study.
back pain; disc pathology; whole-body vibration
The prevalence of knee osteoarthritis (OA) is rising and the search for interventions to mitigate risk is intensifying. This review considers the contribution of occupational activities to disease occurrence and the lessons for prevention.
Systematic search in Embase and Medline covering the period 1996 to November 2011.
Areas of agreement
Reasonably good evidence exists that physical work activities (especially kneeling, squatting, lifting, and climbing) can cause and/or aggravate knee OA. These exposures should be reduced where possible. Obese workers with such exposures are at additional risk of knee OA and should therefore particularly be encouraged to lose weight.
Areas of uncertainty/research need
Workplace interventions and policies to prevent knee OA have seldom been evaluated. Moreover, their implementation can be problematic. However, the need for research to optimise the design of work in relation to knee OA is pressing, given population trends towards extended working life.
Gonarthrosis; employment; occupational; aetiology
Changing demographics mean that many patients with large joint arthritis will work beyond traditional retirement age. This review considers the impact of knee osteoarthritis (OA) on work participation and the relation between work and knee replacement (TKR).
Two systematic searches in Embase and Medline, supplemented by three systematic reviews.
Areas of agreement
Probably, although evidence is limited, knee OA considerably impairs participation in work (labour force participation, work attendance and work productivity).
Areas of uncertainty/research need
Little is known about effective interventions (treatments, work changes and policies) to improve vocational participation in patients with knee OA; or how type of work affects long-term clinical outcomes (e.g. pain, function, the need for revision surgery) in patients with TKRs. The need for such research is pressing and opportune, as increasing numbers of patients with knee OA or TKR expect to work on.
Gonarthrosis; employment; occupational; management; work participation
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.
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.
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).
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.
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.
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.
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.
Exposure to metal fume is a material cause of occupational mortality. The hazard deserves far more attention than it presently receives.
Professional musicians may have high rates of musculoskeletal pain, but few studies have analysed risks by work activities or the psychosocial work environment.
To assess the prevalence and impact of musculoskeletal pain, and its relation to playing conditions, mental health and performance anxiety, in musicians from leading British symphony orchestras.
Musicians from six professional orchestras completed a questionnaire concerning their orchestral duties and physical activities at work; mental health (somatising tendency, mood, demand, support and control at work, performance anxiety); and regional pain in the past four weeks and past 12 months. Prevalence rates were estimated by anatomical site, and associations with risk factors assessed by logistic regression.
Responses were received from 243 musicians (51% of those approached), among whom 210 (86%) reported regional pain in the past 12 months, mainly affecting the neck, low-back, and shoulders. Risks tended to be higher in women, in those with low mood, and especially in those with high somatising scores. Only weak associations were found with psychosocial work stressors and performance anxiety. However, risks differed markedly by instrument category. Relative to string players, the odds of wrist/hand pain were raised 2.9-fold in wind players, but 60% lower in brass players, while the odds of elbow pain were 50% lower among wind and brass players.
Musculoskeletal pain is common in elite professional musicians. A major personal risk factor is somatising tendency, but performance anxiety has less impact. Risks differ substantially by instrument played, offering pointers towards prevention.
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.
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.
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.
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.
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.
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.
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).
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.
lateral epicondylitis; medial epicondylitis; epidemiology; occupation; sickness absence
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.
Occupational Disease; Epidemiology; Rehabilitation; Systematic review; Psychological techniques; Physiotherapy
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.
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).
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.
Varying work schedules are suspected of increasing risks to pregnant women and to fetal wellbeing. In particular, maternal hormonal disturbance arising from sleep deprivation or circadian rhythm disruption might impair fetal growth or lead to complications of pregnancy. Two independent meta-analyses (from 2000 and 2007) reported a small adverse effect of shift work on the risk of preterm delivery (PTD). However, these reviews were based on few high quality studies.
To provide an updated review of the associations of shift work with PTD, low birthweight (LBW), small for gestational age (SGA), and pre-eclampsia.
Search strategy and Selection Criteria
We conducted a systematic search of MEDLINE using combinations of keywords and MeSH terms.
Data Collection and Analysis
for each relevant paper we abstracted standard details, used to summarize design features and rate methodological quality. We calculated pooled estimates of relative risk (RR) in random-effect meta-analyses.
We retrieved 23 relevant studies. The pooled estimate of RR for PTD was 1.16 (95%CI 1.00-1.33, 16 studies), but when five reports of poorer methodological quality were excluded, the estimated RR reduced to 1.03 (95%CI 0.93-1.14). We also observed increased RRs for LBW (1.27, 95%CI 0.93-1.74) and for SGA (1.12, 95%CI 1.03-1.22), which varied little by study quality. Little evidence was found on pre-eclampsia.
These findings suggest that overall, any risk of PTD, LBW, or SGA arising from shift-work in pregnancy is small.
Occupational exposures; shift work; preterm delivery; SGA; meta-analysis
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.
Low back pain; MRI; high intensity zone; disc degeneration; disc prolapse; nerve root compression; symptoms; risk factors