Obesity Paradox in the Intrahospital and Follow-Up Phases of the Acute Coronary Syndrome: A Meta-Analysis and Systematic Review.

BACKGROUND

Obesity is an important risk factor for the development of dyslipidemia, diabetes mellitus, hypertension, coronary artery disease, ventricular dysfunction, congestive heart failure (HF), stroke, and cardiac arrhythmias.

OBJECTIVES

This meta-analysis brings comprehensive evaluation about still controversial association between the body mass index (BMI) and the outcomes of acute coronary syndrome.

METHOD: PubMed/ScienceDirect databases were systematically searched for studies with baseline parameters, primary (HF, cardiogenic shock, cardiac arrest, reinfarction, stroke, death, total in-hospital complications) and secondary outcomes (reinfarction, stroke, death, total major adverse cardiovascular events [MACE]) in relation to BMI strictly classified into four groups (underweight [<18.5 kg/m2], normal weight [18.5-24.9 kg/m2], overweight [25.0-29.9 kg/m2], and obese [≥30.0 kg/m2], grouped into mildly obese [30.0-34.9 kg/m2] and severely obese [≥35.0 kg/m2]).

RESULTS

We included 24 studies, with 585,919 participants (55.5% males), aged 66.8 years. Underweight was negatively associated with hypertension, hyperlipidemia and diabetes, and positively with primary outcomes {HF (odds ratio [OR] = 1.37, confidence interval [CI] [1.15-1.63]), cardiogenic shock (OR = 1.43, CI [1.04-1.98]), stroke (OR = 1.21, CI [1.05-1.40]), overall death (OR = 1.64, CI [1.20-2.26]), total in-hospital complications (OR = 1.39, CI [1.24-1.56])} and secondary outcomes during 34-month follow-up {cardiovascular/overall death (OR = 3.78, CI [1.69-8.49]/OR = 2.82, CI [2.29-3.49]), respectively, total MACE (OR = 2.77, CI [2.30-3.34])} (for all p < 0.05). Obesity had positive association with hypertension, hyperlipidemia, diabetes and smoking, and negative with primary outcomes {reinfarction (OR = 0.83, CI [0.76-0.91]), stroke (OR = 0.67, CI [0.54-0.85]), overall death (OR = 0.55, CI [0.49-0.63]), total in-hospital complications (OR = 0.81, CI [0.70-0.93])} and secondary outcomes {cardiovascular/overall death (OR = 0.77, CI [0.66-0.88]/OR = 0.62, CI [0.53-0.72]), respectively, total MACE (OR = 0.63, CI [0.60-0.77])} (for all p < 0.05). This negative association with several primary outcomes (cardiogenic shock, overall death, total in-hospital complications) and secondary outcomes (cardiovascular/overall death, total MACE) was more pronounced in mild obesity (p < 0.05). These results give an "obesity paradox" with a bimodal pattern (slightly U-shaped).

CONCLUSIONS

Obesity is positively associated with traditional cardiovascular risk factors and negatively with primary and secondary outcomes, which confirms the persistence of overall "obesity paradox."