Body mass index and mortality in heart failure: A meta-analysis
Received 5 November 2007; accepted 14 February 2008.
Background
In patients with chronic heart failure (CHF), previous studies have reported reduced mortality rates in patients with increased body mass index (BMI). The potentially protective effect of increased BMI in CHF has been termed the obesity paradox or reverse epidemiology. This meta-analysis was conducted to examine the relationship between increased BMI and mortality in patients with CHF.
Methods
We searched the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, Scopus, and Web of Science to identify studies with contemporaneous control groups (cohort, case-control, or randomized controlled trials) that examined the effect of obesity on all-cause and cardiovascular mortality. Two reviewers independently assessed studies for inclusion and performed data extraction.
Results
Nine observational studies met final inclusion criteria (total n = 28,209). Mean length of follow-up was 2.7 years. Compared to individuals without elevated BMI levels, both overweight (BMI ∼25.0-29.9 kg/m2, RR 0.84, 95% CI 0.79-0.90) and obesity (BMI ∼≥30 kg/m2, RR 0.67, 95% CI 0.62-0.73) were associated with lower all-cause mortality. Overweight (RR 0.81, 95% CI 0.72-0.92) and obesity (RR 0.60, 95% CI 0.53-0.69) were also associated with lower cardiovascular mortality. In a risk-adjusted sensitivity analysis, both obesity (adjusted HR 0.88, 95% CI 0.83-0.93) and overweight (adjusted HR 0.93, 95% CI 0.89-0.97) remained protective against mortality.
Conclusions
Overweight and obesity were associated with lower all-cause and cardiovascular mortality rates in patients with CHF and were not associated with increased mortality in any study. There is a need for prospective studies to elucidate mechanisms for this relationship.
aDepartment of Clinical Epidemiology, School of Public Health, University of Alberta, Edmonton, Alberta, Canada
bDivision of General Internal Medicine, University of Alberta, Edmonton, Alberta, Canada
cDivision of Nephrology and Hypertension, Harbor-UCLA Medical Center, Torrance, CA
dDivision of Cardiology, UCLA David Geffen School of Medicine, Los Angeles, CA
eFaculty of Nursing, University of Alberta, Edmonton, Alberta, Canada
Reprint requests: Raj Padwal, MD, MSc, Division of General Internal Medicine, University of Alberta, 2E3.22 Walter C. Mackenzie Health Sciences Center, 8440-112 Street, Edmonton, Alberta, Canada T6G 2B7.
There was no project specific funding, but A.O. is supported by a CIHR Strategic Training Fellowship in Tomorrow's Research Cardiovascular Health Professionals; C.M.N. is supported by career salary awards from the Alberta Heritage Foundation for Medical Research; C.M.N. is also supported by New Investigator Awards from the Canadian Institutes of Health Research; G.C.F. is supported by a grant from the National Heart Lung and Blood Institute and the Eliot Corday Foundation; K.K. is supported by a grant from the National Institute of Diabetes, Digestive and Kidney Disease from the NIH and by a Grant-in-Aid from the American Heart Association; and F.A.M. is supported by career salary awards from AHFMR and CIHR as well as the Patient Health Management Chair at the University of Alberta.
ABSTRACT