David Coggon

Risk factors for the incidence and progression of radiographic knee osteoarthritis.

OBJECTIVE Preventive strategies against knee osteoarthritis (OA) require a knowledge of risk factors that influence the initiation of the disorder and its subsequent progression. This population-based longitudinal study was performed to address this issue. METHODS Ninety-nine men and 255 women aged > or =55 years had baseline interviews and weight-bearing knee radiographs in 1990-1991. Repeat radiographs were obtained in 1995-1996 (mean followup duration 5.1 years, median age at followup 75.8 years). Risk factors assessed at baseline were tested for their association with incident and progressive radiographic knee OA by logistic regression. RESULTS Rates of incidence and progression were 2.5% and 3.6% per year, respectively. After adjusting for age and sex, the risk of incident radiographic knee OA was significantly increased among subjects with higher baseline body mass index (odds ratio [OR] 18.3, 95% confidence interval [95% CI] 5.1-65.1, highest versus lowest third), previous knee injury (OR 4.8, 95% CI 1.0-24.1), and a history of regular sports participation (OR 3.2, 95% CI 1.1-9.1). Knee pain at baseline (OR 2.4, 95% CI 0.7-8.0) and Heberdens nodes (OR 2.0, 95% CI 0.7-5.7) were weakly associated with progression. Analyses based on individual radiographic features (osteophyte formation and joint space narrowing) supported differences in risk factors for either feature. CONCLUSION Most currently recognized risk factors for prevalent knee OA (obesity, knee injury, and physical activity) influence incidence more than radiographic progression. Furthermore, these factors might selectively influence osteophyte formation more than joint space narrowing. These findings are consistent with knee OA being initiated by joint injury, but with progression being a consequence of impaired intrinsic repair capacity.

Manual handling activities and risk of low back pain in nurses.

OBJECTIVE--To investigate the risk factors for low back pain in hospital nurses, with particular emphasis on the role of specific nursing activities. METHODS--A cross sectional survey of 2405 nurses employed by a group of teaching hospitals was carried out. Self administered questionnaires were used to collect information about occupational activities, non-occupational risk factors for back symptoms, and history of low back pain. RESULTS--The overall response rate was 69%. Among 1616 women, the lifetime prevalence of back pain was 60% and the one year period prevalence 45%. 10% had been absent from work because of back pain for a cumulative period exceeding four weeks. Rates in men were generally similar to those in women. In women back pain during the previous 12 months was weakly associated with height, and was significantly more common in those who reported frequent non-musculoskeletal symptoms such as headache and low mood. After adjustment for height and non-musculoskeletal symptoms, significant associations were found with frequency of manually moving patients around on the bed, manually transferring patients between bed and chair, and manually lifting patients from the floor. In contrast, no clear increase in risk was found in relation to transfer of patients with canvas and poles, manually lifting patients in and out of the bath, or lifting patients with mechanical aids. Confirmation of these findings is now being sought in a prospective study of the same population. CONCLUSIONS--This study confirms that low back pain is highly prevalent among nurses and is associated with a high level of sickness absence. People who often report non-musculoskeletal symptoms were significantly more likely to report low back pain. Specific manual handling tasks were associated with an increased risk of back pain; however, no such association was found with mechanised patient transfers.

Inflammatory bowel disease and domestic hygiene in infancy

To test the hypothesis that Crohns disease is caused by delayed exposure to enteric infections, we did a case-control study. We compared 133 patients who have Crohns disease and 231 with ulcerative colitis who have controls selected from the general population and matched for age and sex. Crohns disease was more common in subjects whose first houses had a hot-water tap (odds ratio 5.0, 95% CI 1.4-17.3) and separate bathroom (3.3, 1.3-8.3). Ulcerative colitis showed no clear relation to household amenities in infancy. These findings may explain why the incidence of Crohns disease has increased in developed countries over the past 50 years.

Occupational physical activities and osteoarthritis of the knee

OBJECTIVE To assess the risk of knee osteoarthritis (OA) associated with kneeling, squatting, and other occupational activities. METHODS We compared 518 patients who were listed for surgical treatment of knee OA and an equal number of control subjects from the same communities who were matched for sex and age. Histories of knee injury and occupational activities were ascertained at interview, height and weight were measured, and the hands were examined for Heberdens nodes. Data were analyzed by conditional logistic regression. RESULTS After adjustment for body mass index (BMI), history of knee injury, and the presence of Heberdens nodes, risk was elevated in subjects who reported prolonged kneeling or squatting (odds ratio [OR] 1.9; 95% confidence interval [95% CI] 1.3-2.8), walking >2 miles/day (OR 1.9; 95% CI 1.4-2.8), and regularly lifting weights of at least 25 kg (OR 1.7; 95% CI 1.2-2.6) in the course of their work. The risks associated with kneeling and squatting were higher in subjects who also reported occupational lifting, and appeared to interact multiplicatively with the risk conferred by obesity. People with a BMI of > or =30 kg/m2 whose work had entailed prolonged kneeling or squatting had an OR of 14.7 (95% CI 7.2-30.2), compared with subjects with a BMI <25 kg/m2 who were not exposed to occupational kneeling or squatting. CONCLUSION There is now strong evidence for an occupational hazard of knee OA resulting from prolonged kneeling and squatting. One approach to reducing this risk may lie in the avoidance of obesity in people who perform this sort of work.

Prospective cohort study of predictors of incident low back pain in nurses

Abstract Objective: To assess the impact of handling patients and indicators of individual susceptibility on risk of low back pain in nurses. Design: Prospective cohort study with follow up by repeated self administered questionnaires every three months over two years. Setting: NHS university hospitals trust. Subjects: 961 female nurses who had been free from low back pain for at least one month at the time of completing a baseline questionnaire. Main outcome measures: Incidence of new low back pain during follow up and of pain leading to absence from work. Results: Of 838 women who provided data suitable for analysis, 322 (38%) developed low back pain during follow up (mean 18.6 months), including 93 (11%) whose pain led to absence from work. The strongest predictor of new low back pain was earlier history of the symptom, and risk was particularly high if previous pain had lasted for over a month in total and had occurred within the 12 months before entry to the study (incidence during follow up 66%). Frequent low mood at baseline was strongly associated with subsequent absence from work for back pain (odds ratio 3.4; 95% confidence interval 1.4 to 8.2). After adjustment for earlier history of back pain and other potential confounders, risk was higher in nurses who reported frequent manual transfer of patients between bed and chair, manual repositioning of patients on the bed, and lifting patients in or out of the bath with a hoist. Conclusions: Of the indicators of individual susceptibility that were examined, only history of back trouble was sufficiently predictive to justify selective exclusion of some applicants for nursing posts. The main route to prevention of back disorders among nurses is likely to lie in improved ergonomics. Key messages A history of back trouble, particularly if recent and prolonged, is highly predictive of new episodes of back pain There are grounds for excluding nurses with recent and prolonged back pain from the most physically demanding jobs Age, height, and weight are not sufficiently discriminatory for risk of back pain to influence selection and appointment of nurses Back pain is more common in nurses who lift and move patients frequently without the use of mechanical aids Controlled trials are needed to assess the benefits of ergonomic intervention aimed at prevention of back pain in nurses

Occupational activity and osteoarthritis of the knee.

OBJECTIVES--To test the hypothesis that specific occupational physical activities are risk factors for knee osteoarthritis (OA). METHODS--A population-based case-control study of knee osteoarthritis was carried out in which 109 men and women with painful, radiographically confirmed knee OA were compared with 218 age and sex matched controls who had not suffered knee pain and had normal radiographs. Information collected included a lifetime occupational history and details of specific workplace physical activities. RESULTS--After adjustment for obesity and Heberdens nodes, the risk of knee OA was significantly elevated in subjects whose main job entailed more than 30 minutes per day squatting (OR 6.9, 95% CI 1.8-26.4) or kneeling (OR 3.4, 95% CI 1.3-9.1), or climbing more than ten flights of stairs per day (OR 2.7, 95% CI 1.2-6.1). The increase in risk associated with kneeling or squatting appeared to be more marked in subjects whose jobs entailed heavy lifting, but the size of the study did not permit precise delineation of any such interaction. CONCLUSIONS--These data suggest that prolonged or repeated knee bending is a risk factor for knee OA, and that risk may be higher in jobs which entail both knee bending and mechanical loading.

Cancer mortality in workers exposed to chlorophenoxy herbicides and chlorophenols.

Epidemiological studies have revealed an increased risk of cancer, notably soft-tissue sarcomas and non-Hodgkins lymphomas, in people occupationally exposed to chlorophenoxy herbicides, including those contaminated by 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD). We report here a historical cohort study of mortality in an international register of 18,910 production workers or sprayers from ten countries. Exposure was reconstructed through questionnaires, factory or spraying records, and job histories. Cause-specific national death rates were used as reference. No excess was observed in all-cause mortality, for all neoplasms, for the most common epithelial cancers, or for lymphomas. A statistically non-significant two-fold excess risk, based on 4 observed deaths, was noted for soft-tissue sarcoma with a standardised mortality ratio (SMR) of 196 and 95% confidence interval (Cl) 53-502; this was concentrated as a six-fold statistically significant excess, occurring 10-19 years from first exposure in the cohort as a whole (SMR = 606 [165-1552]) and, for the same time period, as a nine-fold excess among sprayers (SMR = 882 [182-2579]). Risks appeared to be increased for cancers of the testicle, thyroid, other endocrine glands, and nose and nasal cavity, based on small numbers of deaths. The excess of soft-tissue sarcomas among sprayers is compatible with a causal role of chlorophenoxy herbicides but the excess does not seem to be specifically associated with those herbicides probably contaminated by TCDD.

Risk of prematurity, low birthweight and pre‐eclampsia in relation to working hours and physical activities: a systematic review

Background: Occupational activities are suspected of having an adverse impact on outcomes of pregnancy. Aim: To assess the evidence relating three major adverse outcomes (preterm delivery, low birthweight (LBW) and pre-eclampsia/gestational hypertension) to five common occupational exposures (prolonged working hours, shift work, lifting, standing and heavy physical workload). Methods: A systematic search of Medline and Embase (1966–December 2005) using combinations of keywords and medical subject heading terms was conducted. For each relevant paper, standard details were abstracted that were then used to summarise the design features of studies, to rate their methodological quality (completeness of reporting and potential for important bias or confounding) and to provide estimates of effect. For studies with similar definitions of exposure and outcome, pooled estimates of relative risk (RR) in meta-analysis were calculated. Results: 53 reports were identified—35 on preterm delivery, 34 on birth weight and 9 on pre-eclampsia or gestational hypertension. These included 21 cohort investigations. For pre-term delivery, extensive evidence relating to each of the exposures of interest was found. Findings were generally consistent and tended to rule out a more than moderate effect size (RR >1.4). The larger and most complete studies were less positive, and pooled estimates of risk pointed to only modest or null effects. For small-for-gestational age, the position was similar, but the evidence base was more limited. For pre-eclampsia and gestational hypertension, it was too small to allow firm conclusions. Conclusions: The balance of evidence is not sufficiently compelling to justify mandatory restrictions on any of the activities considered in this review. However, given some uncertainties in the evidence base and the apparent absence of important beneficial effects, it may be prudent to advise against long working hours, prolonged standing and heavy physical work, particularly late in pregnancy. Our review identifies several priorities for future investigation.

Back pain in Britain: comparison of two prevalence surveys at an interval of 10 years

In Britain, as in many other countries, back pain is a major cause of disability, especially in adults of working age. During the decade to 1993, outpatient attendances for back pain rose fivefold, and the number of days of incapacity from back disorders for which social security benefits were paid more than doubled.1 It is unclear whether this represents an increase in the occurrence of diseases affecting the back or a change in peoples behaviour when they have symptoms. To address this question we compared the prevalence of low back pain and associated disability in two postal surveys 10 years apart.

The Southampton examination schedule for the diagnosis of musculoskeletal disorders of the upper limb

OBJECTIVES Following a consensus statement from a multidisciplinary UK workshop, a structured examination schedule was developed for the diagnosis and classification of musculoskeletal disorders of the upper limb. The aim of this study was to test the repeatability and the validity of the newly developed schedule in a hospital setting. METHOD 43 consecutive referrals to a soft tissue rheumatism clinic (group 1) and 45 subjects with one of a list of specific upper limb disorders (including shoulder capsulitis, rotator cuff tendinitis, lateral epicondylitis and tenosynovitis) (group 2), were recruited from hospital rheumatology and orthopaedic outpatient clinics. All 88 subjects were examined by a research nurse (blinded to diagnosis), and everyone from group 1 was independently examined by a rheumatologist. Between observer agreement was assessed among subjects from group 1 by calculating Cohens κ for dichotomous physical signs, and mean differences with limits of agreement for measured ranges of joint movement. To assess the validity of the examination, a pre-defined algorithm was applied to the nurses examination findings in patients from both groups, and the sensitivity and specificity of the derived diagnoses were determined in comparison with the clinics independent diagnosis as the reference standard. RESULTS The between observer repeatability of physical signs varied from good to excellent, with κ coefficients of 0.66 to 1.00 for most categorical observations, and mean absolute differences of 1.4°–11.9° for measurements of shoulder movement. The sensitivity of the schedule in comparison with the reference standard varied between diagnoses from 58%–100%, while the specificities ranged from 84%–100%. The nurse and the clinic physician generally agreed in their diagnoses, but in the presence of shoulder capsulitis the nurse usually also diagnosed shoulder tendinitis, whereas the clinic physician did not. CONCLUSION The new examination protocol is repeatable and gives acceptable diagnostic accuracy in a hospital setting. Examination can feasibly be delegated to a trained nurse, and the protocol has the benefit of face and construct validity as well as consensus backing. Its performance in the community, where disease is less clear cut, merits separate evaluation, and further refinement is needed to discriminate between discrete pathologies at the shoulder.