1661b Exploring the combined effect of job strain and occupational physical activity on cardiovascular disease incidence

Abstract

Introduction The aim of the study is to investigate the interplay between job strain (JS) and occupational physical activity (OPA) in determining the risk of major cardiovascular diseases (CVD), in a working male population. Methods n=1515 participants to three population-based (WHO-MONICA Brianza II and III survey and PAMELA) North Italian cohorts, 25–64 years old, employed and CVD-free at baseline, were available for the analyses. JS was investigated using the Job Content Questionnaire (MONICA-MOPSY short version), and dichotomized as high vs no-high strain. A habitual OPA score was derived from the Baecke Questionnaire (8 items) and categorised in tertiles. Age-adjusted hazard ratios (HRs) and 95% confidence intervals for incidence of CVD (first coronary heart disease or ischaemic stroke, fatal or non-fatal) events were estimated from Cox-proportional hazard models. A sensitivity analysis was carried out stratifying by sport PA levels. Result In a median 17 years of follow-up, n=102 first CVD events occurred. As compared to the intermediate OPA tertile, workers with low and high OPA showed higher HRs of 1.67 (95% CI: 0.96 to 2.92) and 2.01 (1.17–3.46), respectively. Stratifying by sport PA, the above reported HRs for low and high OPA workers increased to 2.32 (1.15; 4.69) and to 2.54 (1.09; 5.95) when sport PA was below and above the median, respectively. High vs non-high JS workers evidenced an HR of 1.27 (0.76–2.11). When adjusting for age, BMI, alcohol intake, smoking and sport PA, a joint effect was detected between OPA and JS, with the highest HR for workers in the low OPA and high JS category [2.70 (1.17; 6.26)] as compared to workers in the intermediate OPA and non-high JS. Discussion We observed a joint additive effect between sedentary work and high JS on the incidence of cardiovascular events.