BMI poor predictor of mortality in patients with CAD

General

Clinical Question:
How well does body mass index predict mortality in patients with coronary artery disease?

Bottom Line:
Body mass index (BMI) is a poor predictor of total mortality and cardiovascular mortality in patients with established coronary artery disease (CAD). (LOE = 2a-)

Reference:
Romero-Corral A, Montori VM, Somers VK, et al. Association of bodyweight with total mortality and with cardiovascular events in coronary artery disease: a systematic review of cohort studies. Lancet 2006;368:666-678.  [PMID:16920472]

Study Design:
Meta-analysis (other)

Setting:
Various (meta-analysis)

Synopsis:
The authors searched MEDLINE for studies reporting the effect of BMI on total mortality and cardiovascular events in patients with established CAD. They supplemented the search results with data from unpublished sources. The authors analyzed data from 40 studies that included more than 250,000 patients. Two investigators independently assessed the eligibility of each study and 2 others independently assessed study quality. The average follow-up for the studies was 3.8 years. Only 3 studies were of excellent quality, 30 were good, and 7 were "suboptimal." Patients with a BMI of less than 20 had the highest total mortality and cardiovascular mortality rates. Patients who are overweight (BMI = 25 - 29.9) had the lowest total and cardiovascular mortality rates. Obese patients (BMI = 30 - 35) had the same total and cardiovascular mortality rates as patients with normal BMI. Interestingly, although patients with severe obesity (BMI of at least 35) also had the same total mortality rate as those with normal BMI, their cardiovascular mortality rate was higher (relative risk = 1.88; 95% CI, 1.05-3.34). These data are consistent with the amended reports from the Centers for Disease Control that also demonstrated that being overweight was associated with better health outcomes. Additionally, it is well known that BMI is a poor indicator of obesity in fit people. Other factors may be more important than weight; perhaps weight is merely a fellow traveler with the more important risk factors.