The impact of obesity on outcomes of patients admitted to intensive care after cardiac arrest

Studies examining the association between obesity and mortality in cardiac arrest patients have been conflicting which might either be due to residual confounding, or a reliance on estimating the conditional effects rather than the marginal (causal) effects of obesity. We estimated the conditional and causal effects of obesity on mortality in cardiac arrest patients using the Australian and New Zealand Intensive Care Society (ANZICS) Adult Patient Database (APD).This retrospective registry-based cohort study from ICUs of Australia and New Zealand included all ICU patients admitted with cardiac arrest between 2010 and 2020 with height and weight data recorded. The conditional and marginal effects of obesity on mortality was estimated using multivariate binary logistic regression and Targeted Maximum Likelihood Estimation (TMLE) respectively. The primary outcome was in-hospital mortality.A total 13,970 patients had complete data and were available for analysis. In multivariate binary logistic regression, there was no difference in the odds of in-hospital mortality for the obese versus non-obese groups; adjusted OR = 0.95, 95% CI = 0.87-1.03; p 0.25. Results were similar using TMLE (Marginal OR= 0.97; 95% CI = 0.91-1.02, p = 0.62).After adjustment, there was no association between obesity and outcomes in cardiac arrest patients admitted to ICU.