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To monitor the impact of health and safety provisions and inform future preventive strategies, we investigated trends in mortality from established occupational hazards in England and Wales.
We analysed data from death certificates on underlying cause of death and last full-time occupation for 3,688,916 deaths among men aged 20-74 years in England and Wales during 1979-2010 (excluding 1981 when records were incomplete). Proportional mortality ratios (PMRs), standardised for age and social class, were calculated for occupations at risk of specified hazards. Observed and expected numbers of deaths for each hazard were summed across occupations, and the differences summarised as average annual excesses.
Excess mortality declined substantially for most hazards. For example, the annual excess of deaths from chronic bronchitis and emphysema fell from 170.7 during 1979-90 to 36.0 in 2001-10, and that for deaths from injury and poisoning from 237.0 to 87.5. In many cases the improvements were associated with falling PMRs (suggesting safer working practices), but they also reflected reductions in the numbers of men employed in more hazardous jobs, and declining mortality from some diseases across the whole population. Notable exceptions to the general improvement were diseases caused by asbestos, especially in some construction trades and sinonasal cancer in woodworkers.
The highest priority for future prevention of work-related fatalities is the minority of occupational disorders for which excess mortality remains static or is increasing, in particular asbestos-related disease among certain occupations in the construction industry and sinonasal cancer in woodworkers.
PMCID: PMC4872835  PMID: 26976946
Occupation; mortality; trends
Pain  2016;157(5):1028-1036.
To inform case-definition for neck/shoulder pain in epidemiological research, we compared levels of disability, patterns of association and prognosis for pain that was limited to the neck or shoulders (LNSP) and more generalised musculoskeletal pain that involved the neck or shoulder(s) (GPNS). Baseline data on musculoskeletal pain, disability and potential correlates were collected by questionnaire from 12,195 workers in 47 occupational groups (mostly office workers, nurses, and manual workers) in 18 countries (response rate = 70%). Continuing pain after a mean interval of 14 months was ascertained through a follow-up questionnaire in 9,150 workers from 45 occupational groups. Associations with personal and occupational factors were assessed by Poisson regression and summarised by prevalence rate ratios (PRRs). The one-month prevalence of GPNS at baseline was much greater than that of LNSP (35.1% vs. 5.6%), and it tended to be more troublesome and disabling. Unlike LNSP, the prevalence of GPNS increased with age. Moreover, it showed significantly stronger associations with somatising tendency (PRR 1.6 vs. 1.3) and poor mental health (PRR 1.3 vs. 1.1); greater variation between the occupational groups studied (prevalence ranging from 0% to 67.6%) that correlated poorly with the variation in LNSP; and was more persistent at follow-up (72.1% vs. 61.7%). Our findings highlight important epidemiological distinctions between sub-categories of neck/shoulder pain. In future epidemiological research that bases case definitions on symptoms, it would be useful to distinguish pain which is localised to the neck or shoulder from more generalised pain that happens to involve the neck/shoulder region.
PMCID: PMC4833635  PMID: 26761390
Neck pain; shoulder pain; diagnostic classification; case definition; disability; associations; prognosis
Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment syndrome and frequently presents in working-aged adults. Its mild form causes ‘nuisance’ symptoms including dysaesthesia and nocturnal waking. At its most severe however it can significantly impair motor function and weaken pinch grip. This review will discuss the anatomy of the carpal tunnel and the clinical presentation of the syndrome as well as the classification and diagnosis of the condition. Carpal tunnel syndrome has a profile of well-established risk factors including individual factors and predisposing co-morbidities, which will be briefly discussed. However, there is a growing body of evidence for an association between carpal tunnel syndrome and various occupational factors, which will also be discussed. Management of carpal tunnel syndrome, conservative and surgical will be described. Finally, we will discuss the issue of safe return to work post carpal tunnel release surgery and the lack of evidence-based guidelines.
PMCID: PMC4759938  PMID: 26612240
Carpal tunnel syndrome; vibration; repetition; occupation; return to work
4.  Descriptive Epidemiology of Somatising Tendency: Findings from the CUPID Study 
PLoS ONE  2016;11(4):e0153748.
Somatising tendency, defined as a predisposition to worry about common somatic symptoms, is importantly associated with various aspects of health and health-related behaviour, including musculoskeletal pain and associated disability. To explore its epidemiological characteristics, and how it can be specified most efficiently, we analysed data from an international longitudinal study. A baseline questionnaire, which included questions from the Brief Symptom Inventory about seven common symptoms, was completed by 12,072 participants aged 20–59 from 46 occupational groups in 18 countries (response rate 70%). The seven symptoms were all mutually associated (odds ratios for pairwise associations 3.4 to 9.3), and each contributed to a measure of somatising tendency that exhibited an exposure-response relationship both with multi-site pain (prevalence rate ratios up to six), and also with sickness absence for non-musculoskeletal reasons. In most participants, the level of somatising tendency was little changed when reassessed after a mean interval of 14 months (75% having a change of 0 or 1 in their symptom count), although the specific symptoms reported at follow-up often differed from those at baseline. Somatising tendency was more common in women than men, especially at older ages, and varied markedly across the 46 occupational groups studied, with higher rates in South and Central America. It was weakly associated with smoking, but not with level of education. Our study supports the use of questions from the Brief Symptom Inventory as a method for measuring somatising tendency, and suggests that in adults of working age, it is a fairly stable trait.
PMCID: PMC4851348  PMID: 27128094
Epidemiological evidence points strongly to a hazard of hip osteoarthritis from heavy manual work. Harmful exposures may be reduced by elimination or redesign of processes and use of mechanical aids. Reducing obesity might help to protect workers whose need to perform heavy lifting cannot be eliminated. Particularly high relative risks have been reported in farmers, and hip osteoarthritis is a prescribed occupational disease in the UK for long-term employees in agriculture. Even where it is not attributable to employment, hip osteoarthritis impacts importantly on capacity to work. Factors that may influence work participation include the severity of disease, the physical demands of the job, age, and the size of the employer. Published research does not provide a strong guide to the timing of return to work following hip arthroplasty for osteoarthritis, and it is unclear whether patients should avoid heavy manual tasks in their future employment.
PMCID: PMC4759927  PMID: 26612242
Hip; osteoarthritis; arthroplasty; occupation; lifting; manual handling; compensation
To provide further information on the possible carcinogenicity of phenoxy herbicides, and in particular their relationship to soft tissue sarcoma (STS), non-Hodgkin lymphoma (NHL) and chronic lymphocytic leukaemia (CLL).
We extended follow-up to December 2012 for 8,036 men employed at five factories in the UK which had manufactured phenoxy herbicides, or in a contract spraying business. Mortality was compared with that for England and Wales by the person-years method. Nested case-control analyses compared men with incident or fatal STS (n=15) or NHL/CLL (n=74) and matched controls (up to 10 per case).
4,093 men had died, including 2,303 since the last follow-up. Mortality from all causes and all cancers was close to expectation, but an excess of deaths from NHL was observed among men who had worked for ≥ 1 year in jobs with more than background exposure to phenoxy herbicides (19 deaths, standardised mortality ratio 1.85, 95% confidence interval (CI) 1.12-2.89). Four deaths from STS occurred among men potentially exposed above background (3.3 expected). In the nested case-control analyses, there were no significantly elevated risks or consistent trends across categories of potential exposure, for either STS or NHL/CLL. The highest odds ratio (for STS in men who had worked for ≥1 year in potentially exposed jobs) was only 1.30 (95%CI 0.30-5.62).
Our findings are consistent with the current balance of epidemiological evidence. If phenoxy herbicides pose a hazard of either STS or NHL then any absolute increase in risk is likely to be small.
PMCID: PMC4445603  PMID: 25694496
Phenoxy; MCPA; 2,4-D; soft tissue sarcoma; non-Hodgkin lymphoma; chronic lymphocytic leukaemia; cohort; mortality; incidence
British medical bulletin  2015;114(1):75-94.
Phenoxy herbicides have been used widely in agriculture, forestry, parks and domestic gardens. Early studies linked them with soft tissue sarcoma (STS) and non-Hodgkin lymphoma (NHL), but when last reviewed by the International Agency for Research on Cancer in 1986, the evidence for human carcinogenicity was limited.
Sources of data
We searched Medline and Embase, looking for cohort or case-control studies that provided data on risk of STS and/or NHL in relation to phenoxy herbicides, and checked the reference lists of relevant publications for papers that had been missed.
Areas of agreement, areas of controversy
The extensive evidence is not entirely consistent, and a hazard of STS or NHL cannot firmly be ruled out. However, if there is a hazard, then absolute risks must be small.
Growing points, areas timely for developing research
Extended follow-up of previously assembled cohorts may be the most efficient way of further reducing uncertainties.
PMCID: PMC4548713  PMID: 25790819
2,4-D; 2,4,5-T; MCPA; MCPP; epidemiology; cancer
8.  Health and Employment after Fifty (HEAF): a new prospective cohort study 
BMC Public Health  2015;15:1071.
Demographic trends in developed countries have prompted governmental policies aimed at extending working lives. However, working beyond the traditional retirement age may not be feasible for those with major health problems of ageing, and depending on occupational and personal circumstances, might be either good or bad for health. To address these uncertainties, we have initiated a new longitudinal study.
We recruited some 8000 adults aged 50–64 years from 24 British general practices contributing to the Clinical Practice Research Datalink (CPRD). Participants have completed questionnaires about their work and home circumstances at baseline, and will do so regularly over follow-up, initially for a 5-year period. With their permission, we will access their primary care health records via the CPRD. The inter-relation of changes in employment (with reasons) and changes in health (e.g., major new illnesses, new treatments, mortality) will be examined.
CPRD linkage allows cost-effective frequent capture of detailed objective health data with which to examine the impact of health on work at older ages and of work on health. Findings will inform government policy and also the design of work for older people and the measures needed to support employment in later life, especially for those with health limitations.
Electronic supplementary material
The online version of this article (doi:10.1186/s12889-015-2396-8) contains supplementary material, which is available to authorized users.
PMCID: PMC4615332  PMID: 26482655
Ageing population; Older worker; Retirement; CPRD
To provide further information on the risks of lympho-haematopoietic (LH) and other cancers associated with styrene
We extended follow-up to December 2012 for 7,970 workers at eight companies in England which used styrene in the manufacture of glass-reinforced plastics. Mortality was compared with that for England and Wales by the person-years method, and summarised by standardised mortality ratios (SMRs) with 95% confidence intervals (CIs). A supplementary nested case-control analysis compared styrene exposures, lagged by five years, in 122 incident or fatal cases of LH cancer and 1,138 matched controls.
A total of 3,121 cohort members had died (2,022 since the last follow-up). No elevation of mortality was observed for LH cancer, either in the full cohort (62 deaths, SMR 0.90, 95%CI 0.69-1.15), or in those with more than background exposure to styrene (38 deaths, SMR 0.82, 95%CI 0.58-1.14). Nor did the case-control analysis suggest any association with LH cancer. In comparison with background exposure, the odds ratio for non-Hodgkin lymphoma/chronic lymphocytic leukaemia in workers with high exposure (estimated eight-hour time-weighted average of 40-100 ppm) for ≥ I year was 0.54 (95%CI 0.23-1.27). Mortality from lung cancer was significantly elevated, and risk increased progressively across exposure categories, with an SMR of 1.44 (95%CI 1.10-1.86) in workers highly exposed for ≥1 year.
We found no evidence that styrene causes LH cancer. An association with lung cancer is not consistently supported by other studies. It may have been confounded by smoking, but would be worth checking further.
PMCID: PMC4548714  PMID: 25358742
Styrene; glass-reinforced plastics; mortality; lung cancer; non-Hodgkin lymphoma; leukaemia
10.  Sensory impairments, problems of balance and accidental injury at work – a case-control study 
Sensory impairments are becoming increasingly common in the workforces of Western countries. To assess their role in occupational injury, and that of disorders of balance, we undertook a case-control study.
Using the Clinical Practice Research Datalink, which documents all medical consultations, referrals, and diagnoses in primary care for 6% of the British population, we identified 1,348 working-aged patients who had consulted medical services over a 22-year period for workplace injury (cases) and 6,652 age-, sex- and practice-matched controls. Risks were assessed by conditional logistic regression, for earlier recorded diagnoses of visual impairment, common eye diseases, hearing loss, perforated ear drum, non-acute otitis media, and disorders of balance.
In all, 173 (2.2%) subjects had an earlier eye problem, 792 (9.9%) an ear problem (including 336 with impaired hearing and 482 with non-acute otitis media), and 266 (3.3%) a disorder of balance. No associations were found with glaucoma, cataract, retinal disorders, or perforation of the ear drum specifically, but adjusted odds ratios (ORs) were moderately elevated for eye and ear problems more generally, and higher where there was a record of blindness or partial sight (OR 1.90, 95%CI 1.05-3.44) or non-acute otitis media (OR 2.04, 95%CI 1.64-2.54). Risks for non-acute otitis media and for disorders of balance were particularly elevated for consultations in the 12 months preceding injury consultation (OR 2.70, 95%CI 1.58-4.62 and 1.77, 95%CI 1.01-3.11 respectively).
Problems of vision, impairments of hearing, and disorders of balance all may carry moderately increased risks of occupational injury.
PMCID: PMC4467023  PMID: 25523936
Thorax  2014;70(2):198-199.
PMCID: PMC4445601  PMID: 25319209
Pneumococcus; pneumonia; welders; vaccination; mortality
12.  Epilepsy, diabetes mellitus, and accidental injury at work 
To assess the contribution of epilepsy and diabetes to occupational injury.
The Clinical Practice Research Datalink logs primary care data for 6% of the British population, coding all consultations and treatments. Using this we conducted a population-based case-control study, identifying patients aged 16-64 who had consulted over two decades for workplace injury, plus matched controls. By conditional logistic regression we assessed risks for diabetes and epilepsy overall, several diabetic complications and indices of poor control, occurrence of status epilepticus and treatment with hypoglycaemic and anti-epileptic agents.
We identified 1,348 injury cases and 6,652 matched controls. 160 subjects (2%) had previous epilepsy, including 29 injury cases, while 199 (2.5%) had diabetes, including 77 with eye involvement and 52 with a record of poor control. Odds ratios (ORs) for occupational injury were close to unity, both in those with epilepsy (1.07) and diabetes (0.98) and in those prescribed anti-epileptic or hypoglycaemic treatments in the previous year (0.87 to 1.16). We found no evidence of any injury arising directly from a seizure and no-one had consulted about their epilepsy within 100 days before their injury consultation. Two cases and six controls had suffered status epilepticus (OR vs. never had epilepsy 1.61). Risks were somewhat higher for certain diabetic complications (OR 1.44), although lower among those with eye involvement (OR 0.70) or poor diabetic control (0.50). No associations were statistically significant.
No evidence was found that diabetes or epilepsy are important contributors to workplace injury in Britain.
PMCID: PMC4431610  PMID: 24964785
epilepsy; diabetes; accidents; injury
American journal of epidemiology  2014;179(11):1301-1311.
The International Agency for Research on Cancer controversially has classified formaldehyde as causing nasopharyngeal carcinoma and myeloid leukaemia. To provide further information on this question, we extended follow-up of 14,008 chemical workers at six factories in England and Wales, covering the period 1941-2012. Mortality was compared with national death rates, and associations with incident upper airways cancer and leukaemia were explored in nested case-control analyses. Excess deaths were observed from cancers of the oesophagus (100 v 93.1 expected), stomach (182 v 141.4), rectum (107 v 86.8), liver (35 v 26.9) and lung (813 v 645.8), but none of these tumours exhibited a clear exposure-response relationship. Nested case-control analyses of 115 men with upper airways cancer (including one nasopharyngeal cancer), 92 with leukaemia, and 45 with myeloid leukaemia indicated no elevations of risk in the highest exposure category (high exposure for ≥1 year). When the two highest exposure categories were combined the odds ratio for myeloid leukaemia was 1.26 (95%confidence interval: 0.39, 4.08). Our results provide no support for a hazard of myeloid leukaemia, nasopharyngeal carcinoma or other upper airways tumours from formaldehyde, and indicate that any excess risk of these cancers, even from relatively high exposures, is at most small.
PMCID: PMC4189094  PMID: 24714728
Cancer; chemical industry; formaldehyde; mortality; myeloid leukaemia; nasopharyngeal cancer
14.  The role of mental health problems and common psychotropic drug treatments in accidental injury at work, a case-control study 
Mental illness and psychotropic drugs have been linked with workplace injury, but few studies have measured exposures and outcomes independently or established their relative timings. To address this shortcoming, we conducted a case-control study nested within a database prospectively recording injury consultations, diagnoses and drug prescriptions.
The Clinical Practice Research Datalink logs primary care data for 6% of the British population, coding all consultations (by the Read system) and drug prescriptions. We identified 1,348 patients aged 16-64 years from this database who had consulted a family doctor or hospital over a 20-year period for workplace injury (cases, 479 diagnostic codes) and 6,652 age, sex, and practice-matched controls with no such consultation. Groups were compared in terms of consultations for mental health problems (1,328 codes) and prescription of psychotropic drugs prior to the case’s injury consultation, using conditional logistic regression.
In total, 1,846 (23%) subjects had at least one psychiatric consultation before the index date and 1,682 (21%) had been prescribed a psychotropic drug. The odds ratio for prior mental health consultation was 1.44 (P<0.001) and that for psychotropic drug treatment was 1.57 (P<0.001). Risks were significantly elevated for several subclasses of mental health diagnosis (e.g. psychosis, neurosis) and for each of the drug classes analysed. Assuming causal relationships, about 9-10% of all workplace injuries leading to medical consultation were attributable to mental illness or psychotropic medication.
Mental health problems and psychotropic treatments may account for an important minority of workplace injuries.
PMCID: PMC3984107  PMID: 24627304
15.  Work activities and risk of prematurity, low birthweight and pre-eclampsia: an updated review with meta-analysis 
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.
PMCID: PMC3653070  PMID: 23343859
pregnancy; occupation; review; meta-analysis
16.  Evaluation of a case management service to reduce sickness absence 
It is unclear whether and to what extent intensive case management is more effective than standard occupational health services in reducing sickness absence in the healthcare sector.
To evaluate a new return to work service at an English hospital trust.
The new service entailed intensive case management for staff who had been absent sick for longer than four weeks, aiming to restore function through a goal-directed and enabling approach based on a bio-psycho-social model. Assessment of the intervention was by controlled before and after comparison with a neighbouring hospital trust at which there were no major changes in the management of sickness absence. Data on outcome measures were abstracted from electronic databases held by the two trusts.
At the intervention trust, the proportion of 4-week absences which continued beyond 8 weeks fell from 51.7% in 2008 to 49.1% in 2009 and 45.9% in 2010. The reduction from 2008 to 2010 contrasted with an increase at the control trust from 51.2% to 56.1% – a difference in change of 10.7% (95%CI 1.5% to 20.0%). There was also a differential improvement in mean days of absence beyond four weeks, but this was not statistically significant (1.6 days per absence, 95%CI −7.2 to 10.3 days).
Our findings suggest that the intervention was effective, and calculations based on an annual running cost of £57,000 suggest that it was also cost-effective. A similar intervention should now be evaluated at a larger number of hospital trusts.
PMCID: PMC3633198  PMID: 23365116
Sickness absence; case management; intervention; evaluation; cost-effectiveness; healthcare
Pain  2013;154(9):1769-1777.
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.
PMCID: PMC3747979  PMID: 23727463
18.  Patterns of multisite pain and associations with risk factors 
Pain  2013;154(9):1769-1777.
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.
PMCID: PMC3747979  PMID: 23727463
Pain; Multisite; Widespread; Definition; Risk factors
19.  Differences in risk factors for neurophysiologically confirmed carpal tunnel syndrome and illness with similar symptoms but normal median nerve function: a case–control study 
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.
PMCID: PMC3765327  PMID: 23947720
Carpal tunnel syndrome; Nerve conduction; Case–control; Obesity; Vibration; Occupation; Psychosocial; Somatising tendency; Upper limb disorders
20.  Impact of carpal tunnel surgery according to pre-operative abnormality of sensory conduction in median nerve: a longitudinal study 
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.
PMCID: PMC3765505  PMID: 23947746
Carpal tunnel syndrome; Neurophysiology; Case definition; Validity; Surgery; Outcome
21.  Symptoms, signs and nerve conduction velocities in patients with suspected carpal tunnel syndrome 
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.
PMCID: PMC3765787  PMID: 23947775
Epidemiology; Evidence-based medicine; Hand; Nerve compression syndromes; Wrist
22.  Disabling musculoskeletal pain in working populations: Is it the job, the person, or the culture? 
Pain  2013;154(6):856-863.
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.
PMCID: PMC3675684  PMID: 23688828
Low back; Forearm; Pain; International; Socioeconomic; Psychosocial
23.  Professional driving and prolapsed lumbar intervertebral disc diagnosed by magnetic resonance imaging – a case–control study 
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.
PMCID: PMC3436743  PMID: 22249859
back pain; disc pathology; whole-body vibration
24.  Correction: The CUPID (Cultural and Psychosocial Influences on Disability) Study: Methods of Data Collection and Characteristics of Study Sample 
PLoS ONE  2012;7(10):10.1371/annotation/3faf76e5-f73e-427f-9d60-8f94939b0f7e.
PMCID: PMC3491867
25.  Optimal case definitions of upper extremity disorder for use in the clinical treatment and referral of patients 
Arthritis care & research  2012;64(4):573-580.
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.
PMCID: PMC3428871  PMID: 22213545

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