Obesity in adolescent men increases the risk of venous thromboembolism in adult life.

BACKGROUND: As the population of obese and severely obese young adults grows, it is becoming increasingly important to recognize the long-term risks associated with adolescent obesity. OBJECTIVES: This study aimed to determine the association between body mass index (BMI) in young men at enlistment for military service and later risk of venous thromboembolism (VTE). METHODS: Nationwide register-based prospective cohort study of men enlisting 1969 to 2005, followed through the Swedish National Patient and Cause of Death registries. We identified 1 639 838 men (mean age, 18.3 years) free of prior venous thromboembolism, of whom 29 342 were obese (BMI 30 to /= 35 kg m(-2) ). The participants were followed until a first registered diagnosis of VTE. RESULTS: During a median follow-up of 28 years (interquartile interval, 20 to 36 years), 11 395 cases of deep vein thrombosis and 7270 cases of pulmonary embolism were recorded. Compared with men with a BMI of 18.5 to /=35 kg m(-2) had a hazard ratio of 4.95 (95% confidence interval, 4.16 to 5.90). CONCLUSIONS: Men who were obese or severely obese in young adulthood had a marked increase in risk of VTE.