Association between body mass index and clinical outcomes of patients after cardiac arrest and resuscitation: A meta-analysis.

BACKGROUND: Obesity as one of the risk factors for cardiovascular diseases increases mortality in general population. Several clinical studies investigated clinical outcomes in patients with different body mass index (BMI) after cardiac arrest (CA). Controversial data regarding BMI on clinical outcomes in those patients exist in those studies. Therefore, we conducted a meta-analysis to evaluate the effect of BMI on survival condition and neurological prognosis in those patients.

METHODS: We searched Pubmed, Embase, Ovid/Medline and EBM reviews databases for relational studies investigating the association between BMI and clinical outcomes of patients after CA. Seven studies involving 25,035 patients were included in this meta-analysis. Primary outcome was survival condition and secondary outcome was neurological prognosis. Three comparisons were conducted: underweight (BMI<18.5) versus normal weight (18.5≤BMI<25), overweight (25≤BMI<30) versus normal weight and obese (BMI≥30) versus normal weight.

RESULTS: Using normal weight patients as reference, underweight patients had a higher mortality (odds ratio [OR] 1.35; 95% confidence interval [CI] 1.10 to 1.66; P=0.004; I2 =17%). Overweight was associated with increased hospital survival (OR 0.80; 95% CI 0.65 to 0.98; P=0.03; I2 =62%) and better neurological recovery (OR 0.72; 95% CI 0.61 to 0.85; P<0.001; I2 =0%). No significant difference was found in clinical outcomes between obese and normal weight patients.

CONCLUSIONS: Low BMI was associated with lower survival rate in CA patients. Overweight was associated with a higher survival rate and better neurological recovery. Clinical outcomes did not differ between obese and normal weight patients. Further studies are needed to explore the underlying mechanisms.