Joint effects of obesity and body height on the risk of venous thromboembolism: the Tromsø Study.

OBJECTIVE The goal of this study was to investigate the combined effect of obesity and body height on the risk of venous thromboembolism (VTE) in a prospective population-based study. METHODS AND RESULTS Personal characteristics, including measures of obesity and body height, were collected in 26 714 men and women, aged 25 to 97 years, who participated in the Tromsø Study in 1994 to 1995. Incident VTE events were registered through September 1, 2007. There were 461 incident VTE events during a median of 12.5 years of follow-up. A tall stature was associated with increased risk of VTE in normal-weight (body mass index <25 kg/m(2)) and obese (body mass index ≥30 kg/m(2)) men, but not in women. The combination of obesity and tall stature synergistically increased the risk of VTE in both sexes. Tall (≥182 cm), obese men had a 5-fold (multivariable hazard ratio 5.16; 95% CI 2.39 to 11.14) increased risk of VTE compared with normal-weight men with short (≤172 cm) stature. Tall (≥168 cm), obese women had an almost 3-fold (multivariable hazard ratio 2.89; 95% CI 1.31 to 6.35) increased risk of VTE compared with normal-weight, short (≤159 cm) women. CONCLUSION The combination of obesity and a tall stature was associated with a substantially increased risk of VTE, especially in men, suggesting synergistic effects of obesity and height on risk of VTE in both sexes.