1194: THE MORTALITY CAUSAL EFFECT OF POSITIVE FLUID BALANCES SEPSIS SUBTYPES

Abstract

Introduction: Millions of deaths occur each year due to sepsis and many questions regarding best practices remain. Volume of fluid resuscitation is one of these questions. It is thought that certain sepsis subtypes may actually fare worse with positive fluid balances, however, the current recommendation for an initial resuscitation of 30cc/kg of crystalloid fluids remains. Randomized controlled trials are the gold standard for determining causal effect, but are time and cost-intensive. Causal inference using inverse probability of treatment weighting (IPTW) provides a cost-effective alternative. Through causal inference, we will evaluate the mortality effect of positive fluid balances on sepsis subtypes with the hypothesis that pulmonary sepsis would have a worse outcome. Methods: An anonymous, publicly available database was analyzed using preexisting IRB approval. The eICU Collaborative Research Database contains data on over 200000 intensive care unit admissions. The analysis used 138986 patients with 30 initial features. We dropped features with more than 50% missing values. Imputation with Sklearn Iterative Imputator. Data scaled with Sklearn Standard Scaler. Selecting features sequentially with 6 final features was performed using MLxtend. The primary outcome was ICU mortality. Aim was to establish Average Treatment Effect for positive fluid balances in pulmonary sepsis compared with urosepsis. Pulmonary sepsis had 6754 patients compared to 4152 in urosepsis. Using domain knowledge, we built a Directed Acyclic Graph (DAG). We selected Apache IV as the confounder covariate based on our DAG. As effect modifiers, we selected creatinine and age. In both groups, IPTW was performed using IBM DoWhy. Results: Mortality analysis of the pulmonary sepsis group demonstrated an ATE of 0.13 (95% CI [0.08,0.19]). The urosepsis group showed an ATE of 0.06 (95% CI [0.054 -0.067]). Positive fluid balances had an increased causal effect on mortality for the pulmonary sepsis group. Conclusions: Positive fluid balance may be more harmful in certain sepsis subtypes. Pulmonary sepsis has a higher fluid balance-related effect on mortality than urosepsis, as determined by causal inference techniques. We hope that this analysis will lead to a further evaluation of fluids’ varying effects on sepsis subtypes.