TV viewing and incident venous thromboembolism: the Atherosclerotic Risk in Communities Study.

TV viewing is associated with risk of arterial vascular diseases, but has not been evaluated in relation to venous thromboembolism (VTE) risk in Western populations. In 1987-1989, the Atherosclerosis Risk in Communities Study obtained information on the frequency of TV viewing in participants aged 45-64 and followed them prospectively. In individuals free of prebaseline VTE (n = 15, 158), we used a Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of incident VTE according to frequency of TV viewing ("Never or seldom", "Sometimes", "Often" or "Very often"). During the 299,767 person-years of follow-up, we identified 691 VTE events. In a multivariable-adjusted model, the frequency of TV viewing showed a positive dose-response relation with VTE incidence (P for trend = 0.036), in which "very often" viewing TV carried 1.71 (95% CI 1.26-2.32) times the risk of VTE compared with "never or seldom" viewing TV. This association to some degree was mediated by obesity (25% mediation, 95% CI 10.7-27.5). Even among individuals who met a recommended level of physical activity, viewing TV "very often" carried 1.80 (1.04-3.09) times the risk of VTE, compared to viewing TV "never or seldom". Greater frequency of TV viewing was independently associated with increased risk of VTE, partially mediated by obesity. Achieving a recommended physical activity level did not eliminate the increased VTE risk associated with frequent TV viewing. Avoiding frequent TV viewing as well as increasing physical activity and controlling body weight might be beneficial for VTE prevention.