Influence of body mass index on the prognosis of patients successfully resuscitated from out-of-hospital cardiac arrest treated by therapeutic hypothermia

Abstract

Background: Obesity prevalence has dramatically increased over recent years and is associated with cardiovascular diseases, but data are lacking on its prognostic impact in out-of-hospital cardiac arrest (OHCA) patients.

Methods: Data of all consecutive OHCA patients admitted in two cardiac arrest centers from Paris and suburbs between 2005 and 2012 were prospectively collected. Patients treated by therapeutic hypothermia (TH) were included in the analysis. Logistic and Cox regression analyses were used to quantify the association between body mass index (BMI) at hospital admission and day-30 and 1-year mortality respectively.

Results: 818 patients were included in the study (median age 60.9 [50.8-72.7] year, 70.2% male). Obese patients (BMI>30kgm^-2) were older, more frequently male and evidenced more frequently cardiovascular risk factors than normally (18.5<BMI<25kgm^-2) or overweight patients (25<BMI<30kgm^-2). Post-resuscitation shock and therapeutic hypothermia failure were more frequent in obese patients. Overall mortality at day-30 and one-year was 63.8 and 67.2%, respectively. After multivariate adjustment, BMI>30kgm^-2 was independently associated with day-30 mortality (Odds ratio [OR] in comparison with normally weight patients 2.45; 95% confidence interval [95%CI: 1.32-4.56; p<0.01]). Obesity was not associated with one-year mortality (Hazard ratio [HR] 0.99, 95%CI 0.21,4.67; p=0.99) while underweight was associated with one-year mortality in this subgroup of patients (Hazard ratio [HR] 3.94, 95%CI 1.11,14.01; p=0.03).

Conclusion: In the present study, obesity was independently associated with day-30 mortality in successfully resuscitated ICU TH OHCA patients. Further studies are needed to understand the mechanisms that underpin this finding.

Keywords: Cardiac arrest; Obesity; Outcome; Overweight; Prognosis.