Dose-response-relationship between occupational exposure to diesel engine emissions and lung cancer risk: A systematic review and meta-analysis.

BACKGROUND: In 2012, the International Agency for Research on Cancer (IARC) concluded that diesel engine emissions (DEE) emissions cause cancer in humans. However, there is still controversy surrounding this conclusion, due to several studies since the IARC decision citing a lack of evidence of a dose-response relationship. OBJECTIVES: Through a systematic review, we aimed to evaluate all evidence on the association between occupational DEE and lung cancer to investigate whether there is an increased risk of lung cancer for workers exposed to DEE and if so, to describe the dose-response relationship. METHODS: We registered the review protocol with PROSPERO and searched for observational studies in relevant literature databases. Two independent reviewers screened the studies' titles/abstracts and full texts, and extracted and assessed their quality. Studies with no direct DEE measurement but with information on length of exposure for high-risk occupations were assigned exposure values based on the DEE Job-Exposure-Matrix (DEE-JEM). After assessing quality and informativeness, we selected appropriate studies for the dose-response meta-analysis. RESULTS: Sixty-five reports (from thirty-seven studies) were included in the review; one had a low risk of bias (RoB) (RR per 10 µg/m3-years: 1.014 [95%CI 1.007-1.021]). There was an increased, statistically significant risk of lung cancer with increasing DEE exposure for all studies (RR per 10 µg/m3-years = 1.013 [95%CI 1.004-1.021]) as well as for studies with a low RoB in the exposure category (RR per 10 µg/m3-years = 1.008 [95% CI1.001-1.015]). We obtained a doubling dose of 555 µg/m3-years for all studies and 880 µg/m3-years for studies with high quality in the exposure assessment. DISCUSSION: We found a linear positive dose-response relationship for studies with high quality in the exposure domain, even though all studies had an overall high risk of bias. Current threshold levels for DEE exposure at the workplace should be reconsidered.

Influence of physically demanding occupations on the development of osteoarthritis of the hip: a systematic review.

BACKGROUND: Hip osteoarthritis (HOA) is a disabling disease affecting around 33 million people worldwide. People of working age and the elderly are at increased risk of developing HOA and the disease is associated with high costs at individual and societal levels due to sick leaves, job loss, total hip replacements and disability pension. This systematic review evaluated the influence of physically demanding occupations on the development of HOA in men. METHODS: Cohort studies, case-control studies and cross-sectional studies with publications in English or German, which assessed the association between exposure to physically demanding occupations and development of HOA, were searched in electronic databases (Medline, Embase, HSE-Line, Cochrane Library) and conference abstracts from 1990 until May 2020. We assessed the methodological quality of selected studies, interpreted all relative effect estimators as relative risks (RRs) and meta-analytically reviewed the effects of occupations with high physical workloads. All steps are based on a study protocol published in PROSPERO (CRD42015016894). RESULTS: Seven cohort studies and six case-control studies were included. An elevated risk to develop HOA was shown for six physically demanding occupational groups. Working in agriculture including fishery and forestry and food production doubles the risk of HOA. Construction, metal working and sales as well as exposure to whole body vibration while driving vehicles increases the risk by roughly 50 to 60%. Unskilled or basic level workers, who were frequently exposed to repetitive heavy manual work, had nearly a doubled risk (RR 1.89 95%CI: 1.29 to 2.77) compared to workers with lower exposure. CONCLUSIONS: Existing studies state an association between various occupations with high physical workload and an increased risk of developing HOA. High Physical workloads include including lifting and carrying heavy loads, demanding postures, repetitive activities, long standing and running, as well as exposure to body vibrations. Occupational prevention and early detection as well as individual health promotion strategies should place their focus on reducing the impact of high physical strain at work sites.

Occupational risk factors for meniscal lesions: a systematic review and meta-analysis.

BACKGROUND: Meniscal lesions are common and are associated with the development of knee osteoarthritis. Knee-straining activities at work such as kneeling or squatting cause high biomechanical stresses on the knee joints that can lead to acute or chronic injuries. The objective of this systematic review is to update the evidence on the potential relationship between occupational risk factors and meniscal lesions. METHODS: We searched the Medline, Embase and Web of Science databases until August 2021 to identify epidemiological observational studies on the association between occupational risk factors and meniscal lesions. Study selection, data extraction and risk of bias assessment were performed independently by two reviewers. Effect measures were extracted from individual studies and pooled with random effects meta-analysis. Heterogeneity analyses were conducted. We used GRADE (Grades of Recommendations, Assessment, Development and Evaluation) to assess the overall quality of evidence. RESULTS: The database search resulted in 11,006 references, and 46 additional studies were identified through hand search. Twenty-two studies (represented in 25 publications) met the predefined eligibility criteria and nine records were included in the meta-analysis. There was only one study with an overall low risk of bias. Significant associations between occupational risk factors and the development of meniscal lesions were found for kneeling (effect size (ES) 2.15, 95% CI 1.67-2.76), squatting (ES 2.01, 95% CI 1.34-3.03), climbing stairs (ES 2.28, 95% CI 1.58-3.30), lifting and carrying weights ≥ 10 kg (ES 1.63, 95% CI 1.35-1.96), lifting and carrying weights ≥ 25 kg (ES 1.56, 95% CI 1.08-2.24), playing football on a professional level (ES 5.22, 95% CI 3.24-8.41), working as a hard coal miner (ES 5.23, 95% CI 2.16-12.69) and floor layers (ES 1.99, 95% CI 1.43-2.78). The overall quality of evidence according GRADE was moderate to low. CONCLUSION: We found consistent evidence of an increased risk of meniscal lesions by occupational knee-straining exposures. Our findings are important for the development of preventive strategies to reduce work-related knee disorders and work absence. TRIAL REGISTRATION: PROSPERO (registration no. CRD42020196279 ).

The Risk of Knee Osteoarthritis in Professional Soccer Players­a Systematic Review With Meta-Analyses

BACKGROUND: We address the question whether professional soccer players with and without macroinjury of the knee joint are at an elevated risk for knee osteoarthritis. METHODS: A systematic review with meta-analyses was conducted. The study protocol was prospectively registered (registration number CRD42019137139). The MEDLINE, EMBASE, and Web of Science databases were searched for relevant publications; in addition, forward searching was performed, and the listed references were considered. All steps of the process were undertaken independently by two reviewers, and any discordances were resolved by consensus. For all publications whose full text was included, the methods used were critically evaluated. The quality of the evidence was judged using the GRADE criteria. RESULTS: The pooled odds ratio for objectively ascertained osteoarthrosis of the knee was 2.25 (95% confidence interval [1.41-3.61], I2 = 71%). When only radiologically ascertained knee osteoarthrosis was considered, the odds ratio was 3.98 [1.34; 11.83], I2 = 58%). The pooled risk estimator in studies in which knee joint macroinjury was excluded was 2.81 ([1.25; 6.32], I2 = 71%). CONCLUSION: A marked association was found between soccer playing and knee osteoarthritis in male professional soccer players. For female professional soccer players, the risk of knee osteoarthritis could not be assessed because of the lack of data. Knee injuries seem to play an important role in the development of knee osteoarthritis in professional soccer players.

Reply to Seafarers' Occupational Noise Exposure and Cardiovascular Risk. Comments to Bolm-Audorff, U.; et al. Occupational Noise and Hypertension Risk: A Systematic Review and Meta-Analysis. Int. J. Environ. Res. Public Health 2020, 17, 6281.

We are grateful for the insightful comments in [...].

Occupational Risk for Post-Traumatic Stress Disorder and Trauma-Related Depression: A Systematic Review with Meta-Analysis.

There is evidence suggesting that occupational trauma leads to post-traumatic stress disorder (PTSD) and depression. However, there is a lack of high-quality reviews studying this association. We, therefore, conducted a systematic review with a meta-analysis to summarize the evidence of occupational trauma on PTSD and depression. After a database search on studies published between 1994 and 2018, we included 31 studies, of which only four had a low risk of bias. For soldiers exposed to wartime deployment, the pooled relative risk (RR) was 2.18 (95% CI 1.83-2.60) for PTSD and 1.15 (95% CI 1.06-1.25) for depression. For employees exposed to occupational trauma, there also was an increased risk for PTSD (RR = 3.18; 95% CI 1.76-5.76) and for depression (RR = 1.73; 95% CI 1.44-2.08). The overall quality of the evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was moderate; the evidence was high only for the association between workers after exposure to trauma and development of PTSD. The study results indicate an increased risk of PTSD and depression in soldiers after participation in war and in employees after occupational trauma.

Occupational Noise and Hypertension Risk: A Systematic Review and Meta-Analysis.

A number of epidemiological studies report an association between occupational noise exposure and arterial hypertension. Existing systematic reviews report conflicting results, so we conducted an updated systematic review with meta-analysis. We registered the review protocol with PROSPERO (registration no.: CRD 42019147923) and searched for observational epidemiological studies in literature databases (Medline, Embase, Scopus, Web of Science). Two independent reviewers screened the titles/abstracts and full texts of the studies. Two reviewers also did the quality assessment and data extraction. Studies without adequate information on recruitment, response, or without a comparison group that was exposed to occupational noise under 80 dB(A) were excluded. The literature search yielded 4583 studies, and 58 studies were found through hand searching. Twenty-four studies were included in the review. The meta-analysis found a pooled effect size (ES) for hypertension (systolic/diastolic blood pressure ≥140/90 mmHg) due to noise exposures ≥80 dB(A) of 1.81 (95% CI 1.51-2.18). There is no substantial risk difference between men and women, but data concerning this question are limited. We found a positive dose-response-relationship: ES = 1.21 (95% CI 0.78-1.87) ≤ 80 dB(A), ES = 1.77 (95% CI 1.36-2.29) >80-≤85 dB(A), and ES = 3.50 (95% CI 1.56-7.86) >85-≤90 dB(A). We found high quality of evidence that occupational noise exposure increases the risk of hypertension.

Dose-Response Relationship between Physical Workload and Specific Shoulder Diseases-A Systematic Review with Meta-Analysis.

Several epidemiological studies have found an association between shoulder-loaded work activities and specific shoulder diseases. No study has derived the dose-response relationship and resulting doubling dose, important for the recognition of occupational diseases. This systematic review is an update of the van der Molen et al. (2017) review. Based on its methodologies, we identified new studies published up to November 2018. The dose-response relationship between physical occupational demands (hands at/above shoulder level, repetitive movements, forceful work, hand-arm vibrations) and specific shoulder diseases (defined as ICD-10 M 75.1-5: rotator cuff syndrome, bicipital tendinitis, calcific tendinitis, impingement, and bursitis) was derived. No evidence for sex-specific differences in the dose-response relationship was found. If there were at least two studies with comparable exposures, a meta-analysis was carried out. The pooled analysis resulted in a 21% risk increase (95% CI 4-41%) per 1000 h of work with hands above shoulder level. A meta-analysis was not possible for other occupational burdens due to the low number of studies and differing exposure measurements; an estimate of the doubling dose was made based on the cohort study of Dalbøge et al. (2014). To conclude, the present systematic review with meta-analysis contributes to knowledge of the level of exposure at which specific shoulder diseases-particularly rotator cuff lesions-should be recognized as an occupational disease.

[Relationship Between Occupational Trauma, Posttraumatic Stress Disorder and Depression - An Assessment of Systematic Reviews]. / Zusammenhang zwischen beruflichen Traumata, posttraumatischer Belastungsstörung und Depression ­ eine Beurteilung von systematischen Reviews.

In a meta-review systematic reviews were assessed with AMSTAR, a validated instrument for the quality judgement. In a systematic search in Pubmed and PsycINFO during the period 2006 - 2016 8,223 hits were found. The assessment of titles and abstracts and the total publications were done by two authors.35 systematic reviews were included in the study. Most systematic reviews showed a low quality according to the AMSTAR criteria and included frequently primary studies without own control group. The four systematic reviews with at least moderate quality showed a significantly increased risk of soldiers after war deployment for the development of posttraumatic stress disorder (PTSD) and depression. Furthermore we found a clearly increased PTSD-risk in firefighters and paramedics.Because of the at most moderate quality of the included studies the authors came to the conclusion that a systematic review with high quality with inclusion of primary studies with own control group should be done. This paper shows despite the limited quality of the included studies for soldiers, firefighters and paramedics a high occupational PTSD-risk. Soldiers have also an increased depression-risk.

Dose-response relationship between cumulative physical workload and osteoarthritis of the hip - a meta-analysis applying an external reference population for exposure assignment.

BACKGROUND: There is consistent evidence from observational studies of an association between occupational lifting and carrying of heavy loads and the diagnosis of hip osteoarthritis. However, due to the heterogeneity of exposure estimates considered in single studies, a dose-response relationship between cumulative physical workload and hip osteoarthritis could not be determined so far. METHODS: This study aimed to analyze the dose-response relationship between cumulative physical workload and hip osteoarthritis by replacing the exposure categories of the included studies with cumulative exposure values of an external reference population. Our meta-regression analysis was based on a recently conducted systematic review (Bergmann A, Bolm-Audorff U, Krone D, Seidler A, Liebers F, Haerting J, Freiberg A, Unverzagt S, Dtsch Arztebl Int 114:581-8, 2017). The main analysis of our meta-regression comprised six case-control studies for men and five for women. The population control subjects of a German multicentre case-control study (Seidler A, Bergmann A, Jäger M, Ellegast R, Ditchen D, Elsner G, Grifka J, Haerting J, Hofmann F, Linhardt O, Luttmann A, Michaelis M, Petereit-Haack G, Schumann B, Bolm-Audorff U, BMC Musculoskelet Disord 10:48, 2009) served as the reference population. Based on the sex-specific cumulative exposure percentiles of the reference population, we assigned exposure values to each category of the included studies using three different cumulative exposure parameters. To estimate the doubling dose (the amount of physical workload to double the risk of hip osteoarthritis) on the basis of all available case-control-studies, meta-regression analyses were conducted based on the linear association between exposure values of the reference population and the logarithm of reported odds ratios (ORs) from the included studies. RESULTS: In men, the risk to develop hip osteoarthritis was increased by an OR of 1.98 (95% CI 1.20-3.29) per 10,000 tons of weights ≥20 kg handled, 2.08 (95% CI 1.22-3.53) per 10,000 tons handled > 10 times per day and 8.64 (95% CI 1.87-39.91) per 106 operations. These estimations result in doubling dosages of 10,100 tons of weights ≥20 kg handled, 9500 tons ≥20 kg handled > 10 times per day and 321,400 operations of weights ≥20 kg. There was no linear association between manual handling of weights at work and risk to develop hip osteoarthritis in women. CONCLUSIONS: Under specific conditions, the application of an external reference population allows for the derivation of a dose-response relationship despite high exposure heterogeneities in the pooled studies.

Occupational Strain as a Risk for Hip Osteoarthritis.

BACKGROUND: Multiple epidemiological studies have revealed an association between occupational physical strain and the risk of developing hip osteoarthritis. METHODS: To determine the association between the lifting and carrying of heavy loads or other physically demanding work and the risk of hip osteoarthritis (HOA) or total hip replacement (THR), we systematically searched the literature for primary studies on the effects of exposure to physical strain and meta-analytically reviewed the results that were amenable to comparisons across studies. We separately assessed studies that had hip pain as an endpoint. RESULTS: 5 cohort studies and 18 case-control studies were found suitable for inclusion. The lifting of heavy loads increases the risk of HOA or THR: exposure doubles the risk in men (relative risk [RR] 2.09, 95% confidence interval [1.4; 3.1]) and increases it by roughly 40% in women (RR 1.41 [1.0; 1.9]). Physically demanding work consisting of a combination of activities of various kinds (dealing with heavy loads, heavy manual work, or prolonged walking and standing) increases the risk by roughly 150% in men (RR 2.46 [1.3; 4.8]) and 40% in women (RR 1.38 [0.9; 2.2]). Hip pain was also reported more commonly in the exposed groups. CONCLUSION: The studies are moderately to highly heterogeneous. An association exists between years of lifting heavy loads or other kinds of physical strain on the job and the risk of developing osteoarthritis of the hip. The greater the exposure, the greater the risk. The evidence base for risk assessment in women is currently inadequate.

Do Occupational Risks for Low Back Pain Differ From Risks for Specific Lumbar Disc Diseases?: Results of the German Lumbar Spine Study (EPILIFT).

STUDY DESIGN: A multicenter, population based, case-control study. OBJECTIVE: The aim of the present analysis is to clarify potential differences in the "occupational risk profiles" of structural lumbar disc diseases on the one hand, and low back pain (LBP) on the other hand. SUMMARY OF BACKGROUND DATA: Physical workplace factors seem to play an important etiological role. METHODS: We recruited 901 patients with structural lumbar disc diseases (disc herniation or severe disc space narrowing) and 233 control subjects with "low-back-pain." Both groups were compared with 422 "low-back pain free" control subjects. Case history, pain data, neurological deficits, and movement restrictions were documented. LBP was recorded by the Nordic questionnaire on musculoskeletal symptoms. All magnetic resonance imaging, computed tomography, and X-rays were inspected by an independent study radiologist. The calculation of cumulative physical workload was based on a computer-assisted interview and a biomechanical analysis by 3-D-dynamic simulation tool. Occupational exposures were documented for the whole working life. RESULTS: We found a positive dose-response relationship between cumulative lumbar load and LBP among men, but not among women. Physical occupational risks for structural lumbar disc diseases [odds ratio (OR) 3.7; 95% confidence interval (95% CI) 2.3-6.0] are higher than for LBP (OR 1.9; 95% CI 1.0-3.5). CONCLUSION: Our finding points to potentially different etiological pathways in the heterogeneous disease group of LBP. Results suggest that not all of the structural disc damage arising from physical workload leads to LBP. LEVEL OF EVIDENCE: 4.

Occupational polycyclic aromatic hydrocarbon exposure and risk of larynx cancer: a systematic review and meta-analysis.

Polycyclic aromatic hydrocarbons (PAH) are genotoxic substances formed during combustion. Occupational PAH exposure has been shown to increase the risk of lung cancer and may be associated with other respiratory cancers. We conducted a systematic review and meta-analysis to clarify the relationship between occupational PAH exposures and larynx malignancies. We searched EMBASE and MEDLINE (until July 2014) using a series of search strings developed to seek case-control studies or longitudinal studies of workers (Population) exposed to PAHs (Exposure) and their risk for larynx cancer incidence and/or mortality (Outcome). Two independent reviewers screened the titles and abstracts for eligible articles and a third reviewer negotiated consensus. Further assessments of eligibility and sources of bias were conducted in a similar manner. The study results were pooled with random effects meta-analysis. The search resulted in 3377 records. The data of 92 full-text articles representing 63 studies were included and extracted. The majority of studies (n=47) was judged likely to be biased; only 16 studies were judged as methodologically adequate. The pooled effect size was 1.45 (95% CI 1.30 to 1.62; I(2)=30.7%; [Formula: see text]=0.03) for larynx cancer incidence and 1.34 (95% CI 1.18 to 1.53; I(2)=23.8%; [Formula: see text]=0.03) for larynx cancer mortality. While few studies allowed an investigation of dose-response, these indicate a positive dose-response effect. Although most studies may underestimate the true effect due to inexact approximations of PAH exposure, the meta-analysis suggests a robust positive association between PAH and larynx cancer.

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.

Physical workload and accelerated occurrence of lumbar spine diseases: risk and rate advancement periods in a German multicenter case-control study.

OBJECTIVE: In a German multicenter case-control study of lumbar disc diseases, we calculated risk and rate advancement periods (RAP) for physical workload. METHODS: Patients aged 25-70 years with clinically and radiologically verified lumbar disc herniation (286 males, 278 females) or symptomatic lumbar disc narrowing (145 males, 206 females) were compared with population control subjects (453 males and 448 females). For this analysis, all manual handling of objects of about ≥5 kg and postures with trunk inclination of ≥20 °, as assessed by technical experts, were included in the calculation of cumulative lumbar load, determined by biomechanical model calculations. Logistic regression analysis was applied to calculate RAP, adjusted for region. RESULTS: We found a steep positive dose-response relationship between age and lumbar disc narrowing among men as well as women; however, we did not find a monotonic increase in lumbar disc herniation risk with age. As a monotonic increase in disease risk with age constitutes a fundamental assumption underlying the RAP concept, we restricted our RAP analysis to cases with symptomatic lumbar disc narrowing. Among men, there was a positive dose-response relationship between the cumulative lumbar load and the acceleration of lumbar disc narrowing. In the highest exposure category, a RAP of 28.0 years [95% confidence interval (95% CI) 9.7-46.3 years] was found. Among women, the RAP was 8.8 years (95% CI 2.4-15.2 years) in the highest exposure category. CONCLUSION: This study emphasizes the conceptual importance of risk acceleration - causation not only comprises the occurrence of a disease (that without a specific exposure would not have occurred at all) but also the accelerated occurrence of a disease (that without exposure would have occurred later in life).

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.

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.