1. Among 2.3 million individuals (42.3 million patient years of follow-up), in those who had a BMI in the mid-normal range (50th to 74th percentile) at seventeen years of age, the rate of fatal cardiovascular events in adulthood demonstrated a significant increase compared to the 5th to 24th percentiles group.
2. The significantly higher rates of cardiovascular events persisted during the 0-10 year and 30-40 year follow-up period.
Evidence Rating Level: 2 (Good)
Study Rundown: Overweight and obese individuals are estimated to make up a third of the adolescent population in some developed countries. At present, studies that have examined the effects of an upper-normal range BMI during adolescence on cardiovascular mortality have demonstrated mixed findings. This study made use of linking data from two Israeli demographic databases: cause of death data from the Israel Central bureau of statistics and heights and weights from medical evaluations of prior to mandatory military service for seventeen-year-old Israeli citizens. BMIs were grouped according to prespecified percentile ranges. Primary outcomes were the number of deaths from cardiovascular causes.
During 42.3 million patient years of follow-up, a graded increase in risk of death from cardiovascular causes could be seen beginning in the group that was in the 50th to 74th percentiles of BMI. The risk of death, as compared to individuals in the 5th to 24th percentiles, was significantly increased for coronary heart disease, stroke, sudden death, and death from total cardiovascular causes.
This study draws strength from its utilization of two large, population-wide data sets, for which data collection began nearly forty years prior to the study. Its stratification BMIs to delineate the cohort that had an upper-normal range during adolescence is an appropriate design for assessing the threshold at which adolescent BMI begins to confer an increased risk of cardiovascular mortality. Among its limitations are the lack of adult BMI measurements and data on cardiovascular lifestyle risk factors.
Click to read the study in NEJM
Relevant Reading: Childhood Obesity, Other Cardiovascular Risk Factors, and Premature Death
In-Depth [retrospective cohort]: Among the study sample of 2 298 130 Israeli Jewish men and non-Orthodox Jewish women that met criteria for analysis, a total of 42 297 007 person-years of follow-up was available for this study. Among a total of 32 127 deaths in the study sample, 2918 (9.1%) were from cardiovascular causes (coronary heart disease, stroke, and sudden death). Hazard ratios for individuals in the 50th to 74th percentiles at age 17, were significantly higher compared with the reference group in the 5th to 24th percentiles (HR 1.49; 95%CI 1.27–1.76; p < 0.001) for coronary heart disease. In the same comparison for total cardiovascular causes the HR was 1.32 (95%CI 1.18–1.48; p < 0.001), for noncardiovascular cases HR was 1.04 (95%CI 1.01-1,08; p = 0.019), and for all causes HR was 1.06 (95%CI 1.03–1.10; p < 0.001). Hazard ratios for death from cardiovascular causes in these groups increased from 2.0 (95%CI 1.1-3.9) during follow-up for 0 to 10 years to 4.1 (95%CI 3.1-5.4) during follow-up for 30 to 40 years.
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