Association between excessive BMI increase during puberty and risk of cardiovascular mortality in adult men: a population-based cohort study

Background Being overweight during childhood and adolescence is associated with increased risk of cardiovascular disease in adulthood, but the relative contribution of prepubertal childhood BMI and BMI change during puberty to adult mortality due to cardiovascular disease is unknown. We assessed the contribution of these two distinct developmental BMI parameters for cardiovascular mortality in adult men. Methods As a part of the ongoing population-based BMI Epidemiology Study (BEST) in Gothenburg, Sweden, men born between 1945 and 1961 with information on both their childhood BMI at age 8 years and BMI change during puberty were included in the study and followed up until December, 2013. Participants who died or emigrated before age 20 years were excluded from the analysis. BMI was collected from paediatric growth charts and mandatory military conscription tests. Childhood overweight (BMI of >= 17.9 kg/m(2)) was defined according to the Centers for Disease Control and Prevention's cutoff at 8 years of age, and BMI change during puberty was defined as the difference between young adult BMI and childhood BMI (BMI at age 20 years minus BMI at age 8 years). Information on mortality was retrieved from high quality national registers with the participants' ten-digit personal identity number. We used Cox proportional hazard regression to analyse the association between exposures and mortality. The ethics committee of the University of Gothenburg, Sweden, approved the study and waived the requirement for written informed consent. Findings We followed 37 672 Swedish men from age 20 years for a mean of 37.8 years (1 422 185 person-years follow-up). 3188 all-cause deaths and 710 cardiovascular deaths occurred during follow-up. The correlation between childhood BMI and BMI change during puberty was marginal (r=0.06). BMI change during puberty, but not childhood BMI, was independently associated with adult all-cause and cardiovascular mortality in men. Boys that became overweight during puberty (HR 2.39; 95% CI 1.86-3.09) and boys who were overweight consistently throughout childhood and puberty (1.85; 1.28-2.67), but not boys overweight in childhood that normalised during puberty (0.99, 0.65-1.50), had increased risk of cardiovascular mortality compared with participants who were not overweight in childhood or as young adults. The association between BMI change during puberty and cardiovascular mortality was non-linear with a substantial association above a threshold of 6.7 units increase in BMI. Interpretation Excessive BMI increase during puberty is a risk marker of adult cardiovascular mortality. These results indicate that BMI should be monitored during puberty to identify boys with increased risk of adult cardiovascular mortality.