Physically demanding occupations among females and sex-related differences to develop osteoarthritis of the hip: a systematic review and meta-analysis.

BACKGROUND: Hip osteoarthritis (HOA) is a leading cause of disability increasing with age and is more prevalent in women and in various physically demanding occupations. This systematic review identifies and summarises occupational exposures for women in physically demanding occupations and discusses sex differences and consequences. METHODS: In this systematic review, we searched various electronic databases for reports published between date of database inception and October 2022. We included cohort studies and case-control studies that assessed the association between exposure to physically demanding occupations and the development of HOA. We then assessed the methodological quality of selected studies, extracted relative effects, compared the risk for women and men and meta-analytically reviewed the effects of physically demanding occupations. All steps were based on a study protocol published in PROSPERO (CRD42015016894). RESULTS: We included six cohort studies and two case-control studies in this systematic review. These studies showed a considerably increased risk of developing HOA in both sexes. Women working in traditionally female-dominated occupations such as cleaning, sales, catering, childcare and hairdressing that are physically demanding, have a higher risk of developing HOA than men in similarly physically demanding occupations. Conversely, in traditionally male-dominated occupations with a high heterogeneity of work activities, such as agriculture, crafts, construction, as well as in low-skilled occupations, the risk was higher for men. One exception are health occupations, which are grouped together with a wide range of other technical occupations, making it difficult to draw conclusions. CONCLUSIONS: Existing studies indicate an association between various occupations with a high physical workload and an increased risk of developing HOA. Occupational prevention and individual health promotion strategies should focus on reducing the effects of heavy physical workloads at work. The aforementioned as well as early detection should be specifically offered to women in female-dominated occupations and to people working in elementary occupations.

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.

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.

Dinitrotoluene exposure in the copper mining industry and renal cancer: a case-cohort study.

OBJECTIVES: To evaluate the association between dinitrotoluene (DNT) exposure and renal cancer in a case-cohort study. METHODS: This case-cohort study was conducted among men born between 1920 and 1974 (n=16 441) who were gainfully employed between 1953 and 1990 in one of two copper mines in Mansfeld, Saxony-Anhalt, former German Democratic Republic, and followed up till 31 December 2006. The study included 109 cases with renal cancer identified by record linkage with the Common Cancer Registry of the New Federal States of Germany (GKR) or by a network of pathology institutes. A comparison subcohort of 999 cohort members was selected at random from the total cohort. Duration and intensity of inhalation and dermal exposure to DNT were assessed on the basis of a job exposure matrix. A time-dependent Cox proportional hazards model modified for case-cohort design was used to assess the relationship between cumulative inhalation and dermal DNT exposure and renal cancer. RESULTS: Elevated risks were found for medium (HR=2.73; 95% CI 1.00 to 7.42) and high (HR=1.81; 95% CI 0.75 to 4.33) dermal exposure to DNT. Relative risks for medium inhalation exposure to DNT were not increased (HR=0.93; 95% CI 0.48 to 1.79) while relative risks for high inhalation exposure to DNT were elevated to 1.36 (95% CI 0.84 to 2.21). We found a statistically significant HR of 2.12 (95% CI 1.03 to 4.37) for combined medium or high inhalation and medium or high dermal exposure to DNT. CONCLUSIONS: According to our case-cohort study, dermal and inhalation exposure to DNT is associated with increased renal cancer risk.

Cancer incidence among workers occupationally exposed to dinitrotoluene in the copper mining industry.

PURPOSE: Epidemiological and toxicological studies point to a potential carcinogenic effect of dinitrotoluene (DNT), particularly with respect to renal and urothelial cancer. METHODS: The cohort comprised all men born between 1920 and 1974 (n = 16,441) who were gainfully employed between 1953 and 1990 in one of two underground copper mines in Mansfeld, Saxony-Anhalt, former German Democratic Republic, and who were followed up for cancer incidence, 1961-2005. Incident cancer cases were identified by record linkage with the Common Cancer Registry of the New Laender. Standardized incidence ratios (SIR) were calculated with the general population of Saxony-Anhalt as the reference. RESULTS: Standardized incidence ratios for all cancers were not significantly elevated in the cohort (SIR = 1.04; 95 % confidence intervals (CI) 0.96-1.14). We found an increase in lung cancer (SIR = 1.29; 1.13-1.46), but not in kidney cancer (SIR = 1.01; 95 % CI 0.79-1.27) or bladder cancer (SIR = 1.04; 95 % CI 0.82-1.30). Standardized incidence ratios stratified by duration of employment with DNT exposure indicated moderately increased risks for kidney and bladder cancer in cohort members with longer exposure. CONCLUSIONS: The SIR analysis of workers in the copper mining industry in comparison with the general population of Saxony-Anhalt overall did not indicate increased risks for renal or bladder cancer. However, results by years of exposure to DNT suggested weakly increased risks for outcomes of a priori interest, bladder and kidney cancer. A subsequent case-cohort analysis including expert assessment of DNT exposure and identification of additional cancer cases from a network of pathology institutes will provide further insight into a potential etiologic role of DNT in renal and urothelial cancer.

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.

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.