Duration and degree of adiposity: effect on cardiovascular risk factors at early adulthood

The effect of adiposity dynamics throughout adolescence on adult cardiometabolic outcomes is not well known. We aimed to assess the effect of duration and degree of adiposity from adolescence to early adulthood on blood pressure and insulin resistance at 24 years.

We used data from 2253 participants evaluated at 13, 17, 21 and 24 years of age in the EPITeen cohort, Porto, Portugal. The area under the curve of body mass index (BMI_AUC) was computed to summarize duration and degree of BMI for the 11-year period. Outcomes were systolic blood pressure (SBP) and insulin resistance at 24 years. The homeostasis model assessment of insulin resistance (HOMA-IR) was used as an indicator of insulin resistance and the variable was log-transformed. Associations between BMI_AUC and each outcome were estimated by linear regression models.

The median BMI_AUC was 243.1 (223.9-268.6) kg m^-2 in 11 years, corresponding to 22.1 kg m^-2 on average per year. In crude analyses, both BMI_AUC and BMI at 24 years were positively associated with SBP (β=0.096 mm Hg, 95% confidence interval (CI) 0.077; 0.115 for BMI_AUC; β=4.616 mm Hg, 95% CI 3.082; 6.151 for BMI at 24 years) and ln HOMA-IR (β=0.004, 95% CI 0.003; 0.005 for BMI_AUC; β=0.047, 95% CI 0.036; 0.057 for BMI at 24 years). After adjustment for confounders and for BMI at 24 years, the magnitude of the association of BMI_AUC attenuated for both outcomes, mostly for SBP, but the association remained statistically significant. Results using standardized variables confirmed that both outcomes were more strongly associated with BMI at 24 years than with BMI_AUC.

In addition to the effect of adult attained BMI, cumulative exposure to higher BMI throughout adolescence, taking into account duration and degree, was also relevant for adult cardiovascular risk factors, mainly for insulin resistance.