The study finds that higher BMI correlates with increased cardiovascular mortality and morbidity. Interestingly, adults with elevated BMI (>25) seem to live longer with cardiovascular disease (CVD) than those with normal BMI (19-25). I speculate that once CVD develops, the damage from high BMI may become irreversible yet somewhat protective. Future studies will explore the molecular mechanisms behind this phenomenon.
JAMA Cardiology, February 2018
Importance
Prior studies have demonstrated lower all-cause mortality in individuals who are overweight compared with those with normal body mass index (BMI), but whether this may come at the cost of greater burden of cardiovascular disease (CVD) is unknown.
Objective
To calculate lifetime risk estimates of incident CVD and subtypes of CVD and to estimate years lived with and without CVD by weight status.
Design
In this population-based study, we used pooled individual-level data from adults (baseline age, 20-40, 40-60, and 60-80 years) across 10 large US prospective cohorts, with 3.2 million person-years of follow-up from 1964 to 2015. All participants were free of clinical CVD at baseline with available BMI index and CVD outcomes data. Data were analyzed from October 2016 to July 2017. World Health Organization–standardized BMI categories.
Outcomes
Total CVD and CVD subtype, including fatal and nonfatal coronary heart disease, stroke, congestive heart failure, and other CVD deaths. Heights and weights were measured directly by investigators in each study, and BMI was calculated as weight in kilograms divided by height in meters squared. We performed (1) modified Kaplan-Meier analysis to estimate lifetime risks, (2) adjusted competing Cox models to estimate joint cumulative risks for CVD or noncardiovascular death, and (3) the Irwin restricted mean to estimate years lived free of and with CVD.
Results
Of the 190,672 in-person examinations included in this study, the mean age was 46.0 years for men and 58.7 years for women, and 140,835 patients (73.9%) were female. Compared with individuals with a normal BMI (defined as a BMI of 18.5-25), lifetime risks for incident CVD were higher in middle-aged adults in the overweight and obese groups.
Compared with normal weight, among middle-aged men and women, competing hazard ratios for incident CVD were
- Average years lived with CVD were longer for middle-aged adults in the overweight and obese groups compared with adults in the normal BMI group. Similar patterns were observed in younger and older adults.
- 1.21 and 1.32 , respectively, for overweight (BMI, 25.0-30),
- 1.67 and 1.85 for obesity (BMI, 30.0-40), and
- 3.14 and 2.53 for morbid obesity (BMI, ≥40.0).