Body mass index and mortality after acute coronary syndromes: a systematic review and meta-analysis

OBJECTIVE: The association between body mass index (BMI) and mortality after acute coronary syndromes (ACS) is controversial. The objective of this analysis is to summarize the available evidence of this association and perform meta-analysis using adjusted estimates. METHODS AND RESULTS: Systematic review from MEDLINE and EMBASE through May 2015 was performed. Studies were considered eligible if they described the association between BMI and all-cause mortality after ACS, and those reporting adjusted estimates were included in the meta-analysis. We included 35 articles with 316,455 participants, with overall poor to moderate quality. No study reported that overweight, type-I or type-II obesity was related to an increased risk of mortality compared to normal weight. Pooled adjusted estimates from 18 studies (137,975 participants) showed lower adjusted mortality both overweight (RR: 0.83; 95% CI: 0.75-0.91; p < .001; I² 51%) and obese (RR: 0.79; 95% CI: 0.71-0.88; p < .001; I² 33%) categories when compared to normal weight. Heterogeneity was not explained in pre-specified subgroups analysis. CONCLUSIONS: Increased BMI was associated with increased adjusted survival after ACS when compared to normal BMI. Unexplained heterogeneity and suboptimal quality of studies limit the strength of the results. This seemingly paradoxical finding needs to be confirmed with further research.