Anemia and mortality in acute coronary syndromes: a systematic review and meta-analysis

Abstract

Background: Anemia is a common comorbidity among patients with acute coronary syndromes (ACS) and may adversely affect cardiovascular outcomes in these patients. We conducted a systematic review and meta-analysis to examine the association between anemia and mortality among patients with ACS.

Methods: We systematically searched MEDLINE to identify cohort studies and secondary analyses of randomized controlled trials examining the association between anemia and all-cause mortality among patients with ACS. Data were aggregated at 4 follow-up times (inhospital, 30 days, 1 year, and maximal available follow-up) using random-effects meta-analysis models.

Results: Twenty-seven studies met the inclusion criteria, involving 233,144 patients. Anemia was present in 44,519 (19.1%) of these patients. Anemic patients were generally older and had a higher prevalence of comorbidities including diabetes mellitus, congestive heart failure, cerebrovascular disease, and history of major bleeding. Anemia was associated with an increased risk of crude all-cause mortality (relative risk 2.08, 95% CI 1.70-2.55) and reinfarction (relative risk 1.25, 95% CI 1.02-1.53) at maximal available follow-up. When adjusted risk ratios from individual studies' multivariable regression analyses were pooled, the magnitude of the associated mortality risk was attenuated but remained significant at maximal follow-up (hazard ratio 1.49, 95% CI 1.23-1.81). Clinically and statistically significant increases in mortality were observed as early as at 30 days post-ACS and persisted at 1 year.

Conclusions: Anemia in patients with ACS is independently associated with a significantly increased risk of early and late mortality.