The obesity paradox in acute coronary syndrome: a meta-analysis

In the general population, the lowest mortality risk is considered to be for the body mass index (BMI) range of 20-24.9 kg/m(2). In chronic diseases (chronic kidney disease, chronic heart failure or chronic obstructive pulmonary disease) the best survival is observed in overweight or obese patients. Recently above-mentioned phenomenon, called obesity paradox, has been described in patients with coronary artery disease. Our aim was to analyze the relationship between BMI and total mortality in patients after acute coronary syndrome (ACS) in the context of obesity paradox. We searched scientific databases for studies describing relation in body mass index with mortality in patients with ACS. The study selection process was performed according to PRISMA statement. Crude mortality rates, odds ratio or risk ratio for all-cause mortality were extracted from articles and included into meta-analysis. 26 studies and 218,532 patients with ACS were included into meta-analysis. The highest risk of mortality was found in Low BMI patients--RR 1.47 (95 % CI 1.24-1.74). Overweight, obese and severely obese patients had lower mortality compared with those with normal BMI-RR 0.70 (95 % CI 0.64-0.76), RR 0.60, (95 % CI 0.53-0.68) and RR 0.70 (95 % CI 0.58-0.86), respectively. The obesity paradox in patients with ACS has been confirmed. Although it seems to be clear and quite obvious, outcomes should be interpreted with caution. It is remarkable that obese patients had more often diabetes mellitus and/or hypertension, but they were younger and had less bleeding complications, which could have influence on their survival.