Decreases in adiposity reduce the risk of hypertension: Results from a prospective cohort of adolescents

This study aimed to evaluate the effect of age-related changes in body mass index and waist circumference during adolescence on blood pressure levels and incidence of hypertension. Among the 2159 adolescents recruited at 13 years in Porto, Portugal, we evaluated those free of hypertension at baseline and followed-up at 17 years (n = 1377) - EPITeen cohort, 2003-2008. Changes in BMI percentage (BMI%) and waist circumference percentage (WC%) were evaluated continuously as the difference between 13 and 17 years, then categorized in sex-specific quartiles. Hypertension was defined as systolic and/or diastolic blood pressure >= 95th sex- age- and height-specific reference percentile. The association between changes in adiposity and incidence of hypertension was computed through generalized linear models with log link function and Poisson distribution [incidence rate ratios (IRR), 95% confidence intervals (95%CI)], adjusting for baseline adiposity, sex, and family history of hypertension. Overall incidence rate of hypertension was 23.8 (95%CI 19.6-28.8) per 1000 person-years. Participants presenting the highest decrease in BMI% from 13 to 17 years (1st quartile) presented lower SBP at 17y, while for those with increasing BMI% (4th quartile) SBP increased. In comparison to stable BMI% (3rd quartile), decreases in BMI% (1st quartile) were associated with 44% lower risk of hypertension at 17y (IRR = 0.56, 95%CI 0.32-0.97). Increases in BMI% (4th quartile) were associated with increased incidence, although without statistical significance (IRR = 1.11, 95%CI 0.66-1.85). Results were similar when considering changes in WC%. Decreases in BMI and WC throughout adolescence in the whole spectrum of adiposity levels presented potential benefit for blood pressure.