Does Obesity Modify the Relationship between Exposure to Occupational Factors and Musculoskeletal Pain in Men? Results from the GAZEL Cohort Study

OBJECTIVE To analyze relationships between physical occupational exposures, post-retirement shoulder/knee pain, and obesity. METHODS 9 415 male participants (aged 63-73 in 2012) from the French GAZEL cohort answered self-administered questionnaires in 2006 and 2012. Occupational exposures retrospectively assessed in 2006 included arm elevation and squatting (never, <10 years, ≥10 years). "Severe" shoulder and knee pain were defined as ≥5 on an 8-point scale. BMI was self-reported. RESULTS Mean BMI was 26.59 kg/m2 +/-3.5 in 2012. Long-term occupational exposure to arm elevation and squatting predicted severe shoulder and knee pain after retirement. Obesity (BMI≥30 kg/m2) was a risk factor for severe shoulder pain (adjusted OR 1.28; 95% CI 1.03, 1.90). Overweight (adjusted OR 1.71; 1.28,2.29) and obesity (adjusted OR 3.21; 1.90,5.41) were risk factors for severe knee pain. In stratified models, associations between long-term squatting and severe knee pain varied by BMI. CONCLUSION Obesity plays a role in relationships between occupational exposures and musculoskeletal pain. Further prospective studies should use BMI in analyses of musculoskeletal pain and occupational factors, and continue to clarify this relationship.