Weight has U-shaped association with AMI mortality
MedWire News: Body weight is associated with mortality following acute myocardial infarction (AMI), with both underweight and overweight conferring an increased risk, reports an Israeli team.
Doron Aronson (Rambam Medical Center, Haifa, Israel) and co-workers examined the association between body mass index (BMI) and clinical outcomes among 2157 patients with AMI. The mean duration of follow-up was 26 months.
The participants were classified into nine groups based on their BMI at baseline, ranging from below 18.5 kg/m2 to 35.0 kg/m2 and above. The mean BMI was 27.7 kg/m2 and three-quarters of patients had a BMI above 25.0 kg/m2.
Writing in the International Journal of Cardiology, the researchers report that BMI had a U-shaped association with mortality, with the lowest risk being seen at a BMI of 26.5-27.9 kg/m2.
After adjusting for multiple variables, the risk for death was increased for patients in the lowest BMI categories (BMI <25.0 kg/m2) and the highest BMI category (≥35.0 kg/m2), with hazard ratios (HRs) of 2.3 and 1.8, respectively, versus the 26.5-27.9-kg/m2 category.
There was also a significant interaction between BMI and anemia, such that the U-shaped relationship between BMI and mortality was present mainly in patients with anemia.
Indeed, patients in the lower and upper BMI categories with concomitant anemia had a "striking" increase in mortality, with adjusted HRs of 5.1 and 3.2, respectively, versus their non-anemic counterparts in the lowest-risk category.
Discussing their results, Aronson et al identify an "obesity paradox," whereby overweight and obesity are associated with better survival in certain groups of patients with cardiovascular disease, including those with heart failure and acute coronary syndromes.
By contrast, in the general population, overweight and obesity are clearly linked with an increased risk for cardiovascular events and mortality.
The team concludes: "Both obesity and underweight are associated with increased mortality in patients with AMI. The risk of mortality is particularly high among underweight and obese patients with anemia."
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By Joanna Lyford