1. Maximum BMIs in overweight, obese, and obese II categories were associated with increases in risk for all-cause mortality.
2. This relationship between BMI and death was maintained regardless of smoking status, sex, and age.
Evidence Rating Level: 2 (Good)
Study Rundown: The relationship between optimal body mass index (BMI) and all-cause mortality lacks consensus. Some studies have identified an inverse association between those that are overweight and mortality, while others suggest that there is an increased risk of death in those that are overweight and obese. The controversial results of these studies are further compounded due to limitations observed in methodologies. To address these controversial results, the authors of this study aimed to investigate the relationship between maximum BMI over 16 years and subsequent mortality. In general, they observed that being overweight at any point in adulthood increases risk for death. This study is limited in its use of data, which was derived predominantly from white participants of high socioeconomic status. Additionally, there is the possibility of residual confounding by unmeasurable variables. Overall, the results of this study indicate that maximum BMI may be a more useful tool to assess all-cause mortality compared to single baseline BMI assessment. Additionally, the study further emphasizes the importance of healthy weight counseling and obesity-prevention measures to reduce all-cause mortality.
In-Depth [retrospective cohort]: In total, 225 072 men and women were included in this study. Data was derived from 3 prospective cohort studies (the Nurses’ Health Study I, II, and the Health Professionals Follow-Up Study). All participants that had returned 2 questionnaires during the weight history periods for each cohort were included in the analysis, regardless of smoking status, baseline illness, and other characteristics. A general association between high BMI and all-cause mortality was observed. Specifically, maximum BMIs in the overweight (25.0 to 29.9 kg/m2) (multivariate hazard ratio [HR], 1.06 [95% CI, 1.03 to 1/08]), obese I (30.0 to 34.9 kg/m2) (HR, 1.24 [CI, 1.20 to 1.29]), and obese II (≥ 35.0 kg/m2) (HR, 1.73 [CI, 1.66 to 1.80]) categories were associated with increases in risk for all-cause death.
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