D. Coggon

Knee osteoarthritis and obesity

OBJECTIVES: To assess the risk of knee osteoarthritis (OA) attributable to obesity, and the interactions between obesity and other established causes of the disorder.METHODS: We performed a population-based case–control study in three health districts of England (Southampton, Portsmouth and North Staffordshire). A total of 525 men and women aged 45u2005y and over, consecutively listed for surgical treatment of primary knee OA, were compared with 525 controls matched by age, sex and family practitioner.RESULTS: Relative to a body mass index (BMI) of 24.0–24.9u2005kg/m2, the risk of knee OA increased progressively from 0.1 (95% CI 0.0–0.5) for a BMI<20u2005kg/m2 to 13.6 (95% CI 5.1–36.2) for a BMI of 36u2005kg/m2 or higher. If all overweight and obese people reduced their weight by 5u2005kg or until their BMI was within the recommended normal range, 24% of surgical cases of knee OA (95% CI 19–27%) might be avoided. As a risk factor for knee OA obesity interacted more than additively with each of Heberdens nodes, earlier knee injury and meniscectomy. In comparison with subjects of normal weight, without Heberdens nodes, and with no history of knee injury, people with a combination of obesity, definite Heberdens nodes and previous knee injury had a relative risk of 78 (95% CI 17–354).CONCLUSIONS: Our findings give strong support to public health initiatives aimed at reducing the burden of knee OA by controlling obesity. People undergoing meniscectomy or with a history of knee injury might be a focus for targeted advice.

Smoking and musculoskeletal disorders: findings from a British national survey

Objectives: To explore the relation between smoking habits and regional pain in the general population. Methods: A questionnaire was mailed to 21 201 adults, aged 16–64 years, selected at random from the registers of 34 British general practices, and to 993 members of the armed services, randomly selected from pay records. Questions were asked about pain in the low back, neck, and upper and lower limbs during the past 12 months; smoking habits; physical activities at work; headaches; and tiredness or stress. Associations were examined by logistic regression and expressed as prevalence ratios (PRs). Results: Questionnaires were completed by 12 907 (58%) subjects, including 6513 who had smoked at some time, among whom 3184 were current smokers. Smoking habits were related to age, social class, report of headaches, tiredness or stress, and manual activities at work. After adjustment for potential confounders, current and ex-smokers had higher risks than lifetime non-smokers for pain at all of the sites considered. This was especially so for pain reported as preventing normal activities (with PRs up to 1.6 in current v never smokers). Similar associations were found in both sexes, and when analysis was restricted to non-manual workers. Conclusions: There is an association between smoking and report of regional pain, which is apparent even in ex-smokers. This could arise from a pharmacological effect of tobacco smoke (for example, on neurological processing of sensory information or nutrition of peripheral tissues); another possibility is that people with a low threshold for reporting pain and disability are more likely to take up and continue smoking.

Risk factors for incident neck and shoulder pain in hospital nurses.

Aim: To assess the incidence and risk factors for neck and shoulder pain in nurses. Methods: A longitudinal study of neck and shoulder pain was carried out in female nurses at two hospitals in England. Personal and occupational risk factors were assessed at baseline. The self reported incidence of symptoms in the neck and shoulder region was ascertained at three-monthly intervals over two years. A Cox regression model was used to estimate hazard ratios (HRs) for incident neck/shoulder pain during follow up in nurses who had been pain free for at least one month at baseline. Results: The baseline response rate was 56%. Of 903 women who were pain free at baseline, 587 (65%) completed at least one follow up while still in the same job. During an average of 13 months, 34% of these (202 women) reported at least one episode of neck/shoulder pain. The strongest predictor of pain in the neck/shoulder was previous history of the symptom (HRs up to 3.3). For physical exposures at work, the highest risks (HRs up to 1.7) were associated with specific patient handling tasks that involved reaching, pushing, and pulling. Nurses who reported low mood or stress at baseline were more likely to develop neck/shoulder pain later (HR 1.5). Workplace psychosocial factors (including job demands, satisfaction, and control) were not associated with incident neck/shoulder symptoms. Conclusions: Neck/shoulder pain is common among hospital nurses, and patient handling tasks that involve reaching and pulling are the most important target for risk reduction strategies.

Occupational exposure to noise and the attributable burden of hearing difficulties in Great Britain

Aims: To determine the prevalence of self reported hearing difficulties and tinnitus in working aged people from the general population, and to estimate the risks from occupational exposure to noise and the number of attributable cases nationally. Methods: A questionnaire was mailed to 22 194 adults of working age selected at random from the age–sex registers of 34 British general practices (21 201 subjects) and from the central pay records of the British armed services (993 subjects). Information was collected on years of employment in a noisy job; and whether the respondent wore a hearing aid, had difficulty in hearing conversation, or had experienced persistent tinnitus over the past year. Associations of hearing difficulty and tinnitus with noise exposure were examined by logistic regression, with adjustment for age, sex, smoking habits, and frequent complaints of headaches, tiredness, or stress. The findings were expressed as prevalence ratios (PRs) with associated 95% confidence intervals (CIs). Attributable numbers were calculated from the relevant PRs and an estimate of the prevalence of occupational exposure to noise nationally. Results: Some 2% of subjects reported severe hearing difficulties (wearing a hearing aid or having great difficulty in both ears in hearing conversation in a quiet room). In men, the prevalence of this outcome rose steeply with age, from below 1% in those aged 16–24 years to 8% in those aged 55–64. The pattern was similar in women, but severe hearing loss was only about half as prevalent in the oldest age band. Tinnitus was far more common in subjects with hearing difficulties. In both sexes, after adjustment for age, the risk of severe hearing difficulty and persistent tinnitus rose with years spent in a noisy job. In men older than 35 years with 10 or more years of exposure, the PR for severe hearing difficulty was 3.8 (95% CI 2.4 to 6.2) and that for persistent tinnitus 2.6 (95% CI 2.0 to 3.4) in comparison with those who had never had a noisy job. Nationally, some 153 000 men and 26 000 women aged 35–64 years were estimated to have severe hearing difficulties attributable to noise at work. For persistent tinnitus the corresponding numbers were 266 000 and 84 000. Conclusions: Significant hearing difficulties and tinnitus are quite common in men from the older working age range. Both are strongly associated with years spent in a noisy occupation—a predominantly male exposure. The national burden of hearing difficulties attributable to noise at work is substantial.

Knee disorders in the general population and their relation to occupation

Background: Hospital based studies of occupational risk factors for knee disorders are complicated by the possibility of selective referral to hospital of people whose work is made difficult by their symptoms. Aims: To explore the extent of such bias and to assess the association of meniscal injury with occupational activities. Methods: A questionnaire was mailed to a community sample of 2806 men aged 20–59 years in southern England. This asked about lifetime occupational and sporting activities, and any history of knee symptoms lasting 24 hours or longer. Rates of hospital referral were compared in symptomatic men according to their occupational activities. In a nested case-control investigation, the occupational activities of 67 men who reported meniscectomy were compared with those of 335 controls. Results: Among 1404 men who responded to the questionnaire, the lifetime prevalence of knee symptoms was 54%, and in 70% of cases the symptoms had started suddenly, usually while playing sport. Symptomatic men whose work entailed kneeling or squatting were more likely to be referred to an orthopaedic surgeon than the average (28% and 31% versus 24%), especially if they experienced locking of the knee (69% and 73% versus 43%). In the nested case-control study, meniscectomy was associated with playing soccer and work that involved regular kneeling or squatting. Conclusions: Results suggest that hospital referral for knee symptoms is influenced to some extent by patients’ occupational activities. Playing soccer is confirmed as a strong risk factor for knee cartilage injury.

The relative importance of whole body vibration and occupational lifting as risk factors for low-back pain.

Aims: To explore the impact of occupational exposure to whole body vibration (WBV) on low back pain (LBP) in the general population and to estimate the burden of LBP attributable to occupational WBV in comparison with that due to occupational lifting. Methods: A questionnaire including sections on WBV at work, LBP, and potential risk factors was mailed to a community sample of 22 194 men and women of working age. Sources and durations of exposure to occupational WBV were ascertained for the past week and personal vibration doses (eVDV) were estimated. Analysis was confined to subjects reporting exposures in the past week as typical of their work. Associations of LBP with eVDV, driving industrial vehicles, and occupational lifting were explored by logistic regression and attributable numbers were calculated. Results: Significant associations were found between daily lifting of weights greater than 10 kg at work and LBP, troublesome LBP (which made it difficult to put on hosiery), and sciatica (prevalence ratios 1.3 to 1.7); but the risk of these outcomes in both sexes varied little by eVDV and only weak associations were found with riding on industrial vehicles. Assuming causal associations, the numbers of cases of LBP in Britain attributable to occupational WBV were estimated to be 444 000 in men and 95 000 in women. This compared with an estimated 940 000 male cases and 370 000 female cases of LBP from occupational lifting. Conclusions: The burden of LBP in Britain from occupational exposure to WBV is smaller than that attributable to lifting at work.

Occupation and epicondylitis: a population-based study

OBJECTIVEnTo 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.nnnMETHODSnThis was a cross-sectional study of 9696 randomly selected adults aged 25-64 years involving a screening questionnaire and standardized physical examination. Age- and sex-specific prevalence rates of epicondylitis were estimated and associations with occupational risk factors explored.nnnRESULTSnAmong 6038 respondents, 636 (11%) reported elbow pain in the last week. Of those surveyed, 0.7% were diagnosed with lateral epicondylitis and 0.6% with medial epicondylitis. Lateral epicondylitis was associated with manual work [odds ratio (OR) 4.0, 95% CI 1.9, 8.4]. In multivariate analyses, repetitive bending/straightening elbow >1u2009h 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). Five per cent of adults with epicondylitis took sickness absence because of their elbow symptoms in the past 12 months (median 29 days).nnnCONCLUSIONnRepetitive 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.

Reliability of the Southampton examination schedule for the diagnosis of upper limb disorders in the general population

Background: Epidemiological research in the field of soft tissue neck and upper limb disorders has been hampered by the lack of an agreed system of diagnostic classification. In 1997, a United Kingdom workshop agreed consensus definitions for nine of these conditions. From these criteria, an examination schedule was developed and validated in a hospital setting. Objective: To investigate the reliability of this schedule in the general population. Methods: Ninety seven adults of working age reporting recent neck or upper limb symptoms were invited to attend for clinical examination consisting of inspection and palpation of the upper limbs, measurement of active and passive ranges of motion, and clinical provocation tests. A doctor and a trained research nurse examined each patient separately, in random order and blinded to each others findings. Results: Between observer repeatability of the schedule was generally good, with a median κ coefficient of 0.66 (range 0.21 to 0.93) for each of the specific diagnoses considered. Conclusion: As expected, the repeatability of tests is poorer in the general population than in the hospital clinic, but the Southampton examination schedule is sufficiently reproducible for epidemiological research in the general population.

Cigarette smoking, occupational exposure to noise, and self reported hearing difficulties

Aims: To explore the interaction of smoking and occupational exposure to noise as risk factors for hearing difficulty in the general population. Methods: A questionnaire was mailed to 21 201 adults of working age, selected at random from the age-sex registers of 34 British general practices, and to 993 members of the armed services, randomly selected from pay records. Questions were asked about smoking habits, years spent in a noisy occupation, difficulty in hearing conversation, and wearing of a hearing aid. Associations of hearing difficulty with smoking habit were examined by logistic regression and compared across strata of noise exposure, with adjustment for potential confounders. Results: Around half of the respondents had ever smoked, and half of these still smoked. Among 10 418 who provided details on hearing, 348 were classed as having moderate and 311 as having severe hearing difficulty. Risk of hearing difficulty was 3–5-fold higher in those employed for >5 years in noisy work compared with those never employed in a noisy job. Within strata of noise exposure (including those who had never worked in a noisy job), ex- and current smokers had a higher risk of hearing difficulty than lifetime non-smokers. The additional risks were small compared with those of long term noise exposure, and the combination of effects was more consistent with an additive than a multiplicative interaction. Conclusions: Smoking may adversely affect hearing, and workers should be encouraged to refrain from both smoking and exposure to noise. However, the extra risk to hearing incurred by smoking in high ambient noise levels is small relative to that from the noise itself, which should be the main target for preventive measures.

Raynaud's phenomenon, vibration induced white finger, and difficulties in hearing

Background: An association has previously been reported between finger blanching and hearing difficulties, but only in workers with exposure to noise and hand transmitted vibration (HTV). Aims: To explore the association in a community sample, including cases who lacked occupational exposure to noise or HTV. Method: A questionnaire was mailed to 12 606 subjects aged 35–64 years, chosen at random from the age–sex registers of 34 British general practices. Inquiry was made about years of employment in noisy jobs, lifetime exposure to HTV, hearing difficulties and tinnitus, and lifetime history of cold induced finger blanching. Subjects were classed as having severe hearing difficulty if they used a hearing aid or found it difficult or impossible to hear conversation in a quiet room. Associations of finger blanching with hearing difficulties and tinnitus were analysed by logistic regression. Results: Among 8193 respondents were 185 who reported severe hearing difficulty and 1151 who reported finger blanching. After adjustment for age and years of work in noisy jobs, hearing difficulty was about twice as common in men and women who reported finger blanching, including those who had never been importantly exposed to noise and in those never exposed to HTV. Conclusions: These data support an association between finger blanching and hearing loss, which is not explained by confounding occupational exposure to noise, and suggest that it may extend to causes of blanching other than vibration induced white finger. Further investigations are warranted to confirm the association and explore possible mechanisms, such as sympathetic vasoconstriction in the cochlea.