Adolescence BMI and trends in adulthood mortality: A study of 2.16 million adolescents

Context: The consequence of elevated body mass index (BMI) at adolescence on early adulthood mortality rate and on predicted life expectancy is unclear. Objective: The objective of the investigation was to study the relationship between BMI at adolescence and mortality rate as well as the mortality trend over the past 4 decades across the entire BMI range. Design and Setting: The study included a nationwide longitudinal cohort. Participants: A total of 2 159 327 adolescents (59.1% males) born between 1950 and 1993, who were medically evaluated for compulsory military service in Israel, participated in the study. Interventions: Height and weight were measured at age 17 years, and BMI was stratified based on the Centers for Disease Control and Prevention-established percentiles for age and sex. Main Outcome Measure: Incident cases of all-cause mortality before age 50 years were recorded. Cox-proportional hazard models were used to assess mortality rates and its trend overtime. Results: During 43 126 211 person-years of follow-up, 18 530 deaths were recorded. As compared with rates observed in the 25th to 50th BMI percentiles, all-cause mortality continuously increased across BMI range, reaching rates of 8.90/10⁴ and 2.90/10⁴ person-years for men and women with BMI greater than the 97th percentile, respectively. A multivariate analysis adjusted for age, socioeconomic status, education, and ethnicity demonstrated a significant increase in mortality at BMI greater than the 50th percentile (BMI < 20.55 kg/m²) for men and the 85th percentile or greater inwomen(BMI<24.78 kg/m²). During the last 4 decades, a significant decrease in mortality rates was documented in normal-weight participants born between 1970 and 1980 vs those born between 1950 and 1960 (3.60/104 vs 4.99/104 person-years, P > .001). However, no improvement in the survival rate was observed among overweight and obese adolescents during the same time interval. Significant interaction between BMI and birth year was observed (P = .007). Conclusions: BMI at adolescence, within the normal range, is associated with all-cause mortality in adulthood. Mortality rates among overweight and obese adolescents did not improve in the last 40 years, suggesting that preadulthood obesity may attenuate the progressive increase in life expectancy.