Mortality, Cardiovascular, and Medication Outcomes in Patients With Myocardial Infarction and Underweight in a Meta-Analysis of 6.3 Million Patients

Although most of the current evidence on myocardial infarction focuses on obesity, there is growing evidence that patients who are underweight have unfavorable prognosis. This study aimed to explore the prevalence, clinical characteristics, and prognosis of this population at risk. Embase and Medline were searched for studies reporting outcomes in populations who were underweight with myocardial infarction. Underweight and normal weight were defined according to the World Health Organization criteria. A single-arm meta-analysis of proportions was used to estimate the prevalence of underweight in patients with myocardial infarction, whereas a meta-analysis of proportions was used to estimate the odds ratio of all-cause mortality, medications prescribed, and cardiovascular outcomes. Twenty-one studies involving 6,368,225 patients were included, of whom 47,866 were underweight. The prevalence of underweight in patients with myocardial infarction was 2.96% (95% confidence interval 1.96% to 4.47%). Despite having fewer classical cardiovascular risk factors, patients who were underweight had 66% greater hazard for mortality (hazard ratio 1.66, 95% confidence interval 1.44 to 1.92, p