Sex-specific associations between adolescent categories of BMI with cardiovascular and non-cardiovascular mortality in midlife

CONTEXT: Most studies linking long-term consequences of adolescent underweight and obesity are limited to men. OBJECTIVE: To assess the sex-specific association of adolescent BMI with cardiovascular- and non-cardiovascular-related mortality in young adulthood and midlife. SETTING: A nationwide cohort. PARTICIPANTS: 927,868 women, 1,366,271 men. INTERVENTIONS: Medical examination data at age 17, including BMI, were linked to the national death registry. MAIN OUTCOMES: Death attributed to cardiovascular (CVD) and non-CVD causes. RESULTS: During 17,346,230 women-years and 28,367,431 men-years of follow-up, there were 451 and 3208 CVD deaths, respectively, and 6235 and 22,223 non-CVD deaths, respectively. Compared to low-normal BMI (18.5–22.0 kg/m(2)), underweight women had a lower adjusted risk for CVD mortality (Cox hazard ratio (HR) = 0.68; 95% CI 0.46–0.98) in contrast to underweight men (HR = 0.99; 0.88–1.13). The latter were at higher risk for non-CVD mortality (HR = 1.04; 1.00–1.09), unlike underweight women (HR = 1.01; 0.93–1.10). Findings, which persisted when the study sample was limited to those with unimpaired health, were accentuated for the obese with ≥ 30 years follow-up. Both sexes exhibited similarly higher risk estimates already in the high-normal BMI range (22.0 ≤ BMI < 25.0 kg/m(2)) with overall no interaction between sex and BMI (p = 0.62). Adjusted spline models suggested lower BMI values for minimal mortality risk among women (16.8 and 18.2 kg/m(2)) than men (18.8 and 20.0 kg/m(2)), for CVD and non-CVD death, respectively. CONCLUSIONS: Underweight adolescent females have favorable cardiovascular outcomes in adulthood. Otherwise the risk patterns were similar between the sexes. The optimal BMI value for women and men with respect to future CVD outcomes is within or below the currently accepted low-normal BMI range. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12933-018-0727-7) contains supplementary material, which is available to authorized users.