Work-related lesions of the supraspinatus tendon: a case-control study.

OBJECTIVES: To examine the dose-response relationship between cumulative duration of work with highly elevated arms (work above shoulder level) as well as of manual material handling and ruptures of the supraspinatus tendon in a population-based case-control study. METHODS: In 14 radiologic practices, we recruited 483 male patients aged 25-65 with radiographically confirmed partial (n = 385) or total (n = 98) supraspinatus tears associated with shoulder pain. A total of 300 male control subjects were recruited. Data were gathered in a structured personal interview. To calculate cumulative exposure, the self-reported duration of lifting/carrying of heavy loads (>20 kg) as well as the duration of work with highly elevated arms was added up over the entire working life. RESULTS: The results of our study support a dose-response relationship between cumulative duration of work with highly elevated arms and symptomatic supraspinatus tendon tears. For a cumulative duration of >3,195 h work above shoulder level, the risk of a supraspinatus tendon rupture is elevated to 2.0 (95% CI 1.1-3.5), adjusted for age, region, lifting/carrying of heavy loads, handheld vibration, apparatus gymnastics/shot put/javelin/hammer throwing/wrestling, and tennis. The cumulative duration of carrying/lifting of heavy loads also yields a positive dose-response relation with disease (independent from work above shoulder level and from handheld vibration), with an adjusted odds ratio of 1.8 (95% CI 1.0-3.2) in the highest exposure category (>77 h). We find an increased risk for subjects exposed to handheld vibration with an adjusted OR of 3.2 (95% CI 1.7-5.9) in the highest exposure category (16 years or more in the job with exposure), but a clear dose-response relationship is lacking. CONCLUSIONS: This study points to a potential etiologic role of long-term cumulative effects of work with highly elevated arms and heavy lifting/carrying on shoulder tendon disorders.

Lifestyle factors and lumbar disc disease: results of a German multi-center case-control study (EPILIFT).

INTRODUCTION: In the large-scale case-control study EPILIFT, we investigated the dose-response relationship between lifestyle factors (weight, smoking amount, cumulative duration of different sports activities) and lumbar disc disease. METHODS: In four German study regions (Frankfurt am Main, Freiburg, Halle/Saale, Regensburg), 564 male and female patients with lumbar disc herniation and 351 patients with lumbar disc narrowing (chondrosis) aged 25 to 70 years were prospectively recruited. From the regional population registers, 901 population control subjects were randomly selected. In a structured personal interview, we enquired as to body weight at different ages, body height, cumulative smoking amount and cumulative duration of different sports activities. Confounders were selected according to biological plausibility and to the change-in-estimate criterion. Adjusted, gender-stratified odds ratios with 95% confidence intervals were calculated using unconditional logistic regression analysis. RESULTS: The results of this case-control study reveal a positive association between weight and lumbar disc herniation as well as lumbar disc narrowing among men and women. A medium amount of pack-years was associated with lumbar disc herniation and narrowing in men and women. A non-significantly lowered risk of lumbar disc disease was found in men with high levels of cumulative body building and strength training. CONCLUSIONS: According to our multi-center case-control study, body weight might be related to lumbar disc herniation as well as to lumbar disc narrowing. Further research should clarify the potential protective role of body building or strength training on lumbar disc disease.

Case-control study of knee osteoarthritis and lifestyle factors considering their interaction with physical workload.

AIMS: The aim of this study is to examine the dose-response relationships between age, "lifestyle factors" (body mass index, tobacco smoking, sports), and symptomatic knee osteoarthritis in a population-based case-control study. Additionally, the study aims to investigate the mode of interaction between body mass index (BMI) and physical workload (occupational kneeling/squatting and lifting/carrying of loads) with respect to the risk of symptomatic knee osteoarthritis. METHODS: In five orthopedic clinics and five practices, 295 male patients aged 25-70 with radiographically confirmed knee osteoarthritis associated with chronic complaints were recruited. The control group comprised 327 male control subjects. In a structured personal interview, body weight at different ages, body height, cumulative amount of smoking, and cumulative duration of different sports activities until the date of first diagnosis of knee osteoarthritis were elicited. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were calculated using unconditional logistic regression analysis. An interaction analysis for the parameters BMI and kneeling/squatting respective lifting/carrying of loads was performed. Population attributable risks (PAR) for knee osteoarthritis were determined for BMI solely and for the combination of BMI with occupational kneeling/squatting and lifting/carrying of loads, respectively. RESULTS: Age and overweight were strongly associated with the diagnosis of knee osteoarthritis. Compared with persons less than 35 years old, persons who were at least 65 years old had an odds ratio (OR) of 19.0 (95% CI 6.1-58.7) for knee osteoarthritis. Persons with a BMI > or = 28.41 kg/m2 had a strongly elevated risk of knee osteoarthritis (OR 10.8; 95% CI 4.8-24.3) compared to persons with a BMI < 22.86 kg/m2. Heavy tobacco smoking (> or = 55.5 pack years) was associated with a decreased knee osteoarthritis risk in comparison with never-smoking (OR 0.2; 95% CI 0.1-0.5). Ball games (handball, volleyball, basketball) and cycling were associated with symptomatic knee osteoarthritis (OR 4.0; 95% CI 1.8-8.9 and OR 3.7; 95% CI 1.7-7.8 in the highest category of cumulative duration, respectively); to a weaker degree jogging, swimming, and soccer also were positively related to symptomatic knee osteoarthritis. Combining the two parameters, BMI and kneeling/squatting into one variable led to a multiplicative interaction mode for symptomatic knee osteoarthritis. For persons with elevated BMI in combination with moderate to high exposure to occupational kneeling/squatting, the population attributable risk (PAR) was 4%. The PAR for elevated BMI in combination with moderate to high exposure to occupational lifting/carrying of loads was 7%. CONCLUSIONS: In accordance with the literature, we find a strong association between BMI and knee osteoarthritis risk. Considering the relatively high prevalence of occupational manual materials handling, prevention of knee osteoarthritis should not only focus on body weight reduction, but should also take into account work organizational measures particularly aiming to reduce occupational lifting and carrying of loads.

Asbestos exposure and malignant lymphoma: a multicenter case-control study in Germany and Italy.

AIMS: To analyze the relationship between asbestos exposure and malignant lymphoma in a multicenter case-control study conducted in Germany and Italy according to a common core protocol. METHODS: Male and female patients with malignant lymphoma (n = 1,034) between 18 and 80 years of age were prospectively recruited in six study areas in Germany (Ludwigshafen/Upper Palatinate, Heidelberg/Rhine-Neckar-County, Würzburg/Lower Frankonia, Hamburg, Bielefeld/East Westphalia, and Munich) and in two study areas in Sardinia, Italy (Cagliari and Nuoro provinces). A total of 1,173 population control subjects were drawn from population registers. In a structured personal interview, we elicited a complete occupational history, including every occupational period that lasted at least 1 year. On the basis of job task-specific supplementary questionnaires, trained experts assessed the exposure to asbestos. As a measure of cumulative asbestos exposure on a time by intensity scale, fiber-years were calculated. 12 cases (1.2%) and 12 control subjects (1.0%) had a cumulative asbestos exposure of more than 2.6 fiber-years (highest exposure category according to the 90th percentile of exposed control subjects). Odds ratios (OR) and 95% confidence intervals (CI) were calculated using unconditional logistic regression analysis adjusted for age, sex and study region. Patients with specific lymphoma sub-entities were additionally compared with the entire control group. RESULTS: We observed no statistically significant association between cumulative asbestos exposure and the risk of any lymphoma subtype. An elevated risk was found for the association between exposure to more than 2.6 fiber-years and multiple myeloma (OR = 6.0; 95% CI 1.4-25.1); however, numbers were small (n = 3 cases, all of them from Italy; n = 12 control subjects). CONCLUSIONS: Our study does not support an association between asbestos exposure and risk of malignant lymphoma.

Cumulative occupational lumbar load and lumbar disc disease--results of a German multi-center case-control study (EPILIFT).

BACKGROUND: The to date evidence for a dose-response relationship between physical workload and the development of lumbar disc diseases is limited. We therefore investigated the possible etiologic relevance of cumulative occupational lumbar load to lumbar disc diseases in a multi-center case-control study. METHODS: In four study regions in Germany (Frankfurt/Main, Freiburg, Halle/Saale, Regensburg), patients seeking medical care for pain associated with clinically and radiologically verified lumbar disc herniation (286 males, 278 females) or symptomatic lumbar disc narrowing (145 males, 206 females) were prospectively recruited. Population control subjects (453 males and 448 females) were drawn from the regional population registers. Cases and control subjects were between 25 and 70 years of age. In a structured personal interview, a complete occupational history was elicited to identify subjects with certain minimum workloads. On the basis of job task-specific supplementary surveys performed by technical experts, the situational lumbar load represented by the compressive force at the lumbosacral disc was determined via biomechanical model calculations for any working situation with object handling and load-intensive postures during the total working life. For this analysis, all manual handling of objects of about 5 kilograms or more and postures with trunk inclination of 20 degrees or more are included in the calculation of cumulative lumbar load. Confounder selection was based on biologic plausibility and on the change-in-estimate criterion. Odds ratios (OR) and 95% confidence intervals (CI) were calculated separately for men and women using unconditional logistic regression analysis, adjusted for age, region, and unemployment as major life event (in males) or psychosocial strain at work (in females), respectively. To further elucidate the contribution of past physical workload to the development of lumbar disc diseases, we performed lag-time analyses. RESULTS: We found a positive dose-response relationship between cumulative occupational lumbar load and lumbar disc herniation as well as lumbar disc narrowing among men and women. Even past lumbar load seems to contribute to the risk of lumbar disc disease. CONCLUSION: According to our study, cumulative physical workload is related to lumbar disc diseases among men and women.

The role of cumulative physical work load in symptomatic knee osteoarthritis - a case-control study in Germany.

OBJECTIVES: To examine the dose-response relationship between cumulative exposure to kneeling and squatting as well as to lifting and carrying of loads and symptomatic knee osteoarthritis (OA) in a population-based case-control study. METHODS: In five orthopedic clinics and five practices we recruited 295 male patients aged 25 to 70 with radiographically confirmed knee osteoarthritis associated with chronic complaints. A total of 327 male control subjects were recruited. Data were gathered in a structured personal interview. To calculate cumulative exposure, the self-reported duration of kneeling and squatting as well as the duration of lifting and carrying of loads were summed up over the entire working life. RESULTS: The results of our study support a dose-response relationship between kneeling/squatting and symptomatic knee osteoarthritis. For a cumulative exposure to kneeling and squatting > 10.800 hours, the risk of having radiographically confirmed knee osteoarthritis as measured by the odds ratio (adjusted for age, region, weight, jogging/athletics, and lifting or carrying of loads) is 2.4 (95% CI 1.1-5.0) compared to unexposed subjects. Lifting and carrying of loads is significantly associated with knee osteoarthritis independent of kneeling or similar activities. CONCLUSION: As the knee osteoarthritis risk is strongly elevated in occupations that involve both kneeling/squatting and heavy lifting/carrying, preventive efforts should particularly focus on these "high-risk occupations".

Solvent exposure and malignant lymphoma: a population-based case-control study in Germany.

AIMS: To analyze the relationship between exposure to chlorinated and aromatic organic solvents and malignant lymphoma in a multi-centre, population-based case-control study. METHODS: Male and female patients with malignant lymphoma (n = 710) between 18 and 80 years of age were prospectively recruited in six study regions in Germany (Ludwigshafen/Upper Palatinate, Heidelberg/Rhine-Neckar-County, Würzburg/Lower Frankonia, Hamburg, Bielefeld/Gütersloh, and Munich). For each newly recruited lymphoma case, a gender, region and age-matched (+/- 1 year of birth) population control was drawn from the population registers. In a structured personal interview, we elicited a complete occupational history, including every occupational period that lasted at least one year. On the basis of job task-specific supplementary questionnaires, a trained occupational physician assessed the exposure to chlorinated hydrocarbons (trichloroethylene, tetrachloroethylene, dichloromethane, carbon tetrachloride) and aromatic hydrocarbons (benzene, toluene, xylene, styrene). Odds ratios (OR) and 95% confidence intervals (CI) were calculated using conditional logistic regression analysis, adjusted for smoking (in pack years) and alcohol consumption. To increase the statistical power, patients with specific lymphoma subentities were additionally compared with the entire control group using unconditional logistic regression analysis. RESULTS: We observed a statistically significant association between high exposure to chlorinated hydrocarbons and malignant lymphoma (Odds ratio = 2.1; 95% confidence interval 1.1-4.3). In the analysis of lymphoma subentities, a pronounced risk elevation was found for follicular lymphoma and marginal zone lymphoma. When specific substances were considered, the association between trichloroethylene and malignant lymphoma was of borderline statistical significance. Aromatic hydrocarbons were not significantly associated with the lymphoma diagnosis. CONCLUSION: In accordance with the literature, this data point to a potential etiologic role of chlorinated hydrocarbons (particularly trichloroethylene) and malignant lymphoma. Chlorinated hydrocarbons might affect specific lymphoma subentities differentially. Our study does not support a strong association between aromatic hydrocarbons (benzene, toluene, xylene, or styrene) and the diagnosis of a malignant lymphoma.

Sun exposure and malignant lymphoma: a population-based case-control study in Germany.

Although some causes for malignant lymphoma are known their etiology is not well understood so far. We analyze the relationship between sun exposure and malignant lymphoma in a multicenter, population-based case-control study. Patients with malignant lymphoma (n = 710, 18-80 years) were prospectively recruited in 6 study regions in Germany. For each case, a gender, region and age-matched control was drawn from population-registers. In personal interviews, lifetime holidays spent in sunny climate, outdoor leisure activities and sunbed or sunlamp use were recorded. On basis of job task-specific supplementary questionnaires, an occupational physician assessed the cumulative working time outside. Odds ratios (OR) and 95%-confidence-intervals (CI) were calculated using conditional logistic regression analysis, adjusted for smoking and alcohol consumption. To increase statistical power, patients with specific lymphoma subentities were additionally compared with the entire control group using unconditional logistic regression. We observed a reduced overall lymphoma risk among subjects having spent vacations at sunny climates or frequently used sunbeds or sunlamps. The analysis of lymphoma subentities revealed similar results with the exception of T-NHL and follicular lymphoma which were positively associated with outdoor leisure activities. While cumulative working time outside appeared unrelated to NHL overall and most subentities, it was negatively associated with follicular lymphoma and weakly positively to HL. This data suggest that exposure to natural and artificial ultraviolet radiation may reduce the OR for lymphoma in this study population.

Sleep apnea and occupational exposure to solvents.

OBJECTIVES: The possible effects of exposure to neurotoxic substances such as gasoline, diesel fuel, paint, varnish, and solvents on the pathogenesis of obstructive sleep apnea were examined. METHODS: Four hundred and forty-three persons with incident obstructive sleep apnea were recruited within the framework of a case-referent study. A reference population (N=397) was included as the first reference group. In addition 106 patients whose sleep laboratory findings confirmed that they were not suffering from obstructive sleep apnea were then included as a second reference group. Data were gathered with a questionnaire which had to be filled out by the persons with obstructive sleep apnea (cases) and the referents themselves. In the assessment of occupational exposure the questionnaires were filled out by the subjects themselves, and a job-exposure matrix was also used. Data were analyzed using logistic regression to control for age, region, body mass index, cigarette smoking, and alcohol consumption. RESULTS: None of the exposures were statistically significantly associated with obstructive sleep apnea. There was no correlation with occupation. Only current activities in service occupations revealed an increased odds ratio, 1.6 (95% confidence interval 1.1-2.4). CONCLUSIONS: No suggestion was found of an association between exposure to solvents and obstructive sleep apnea.