Risk factors for mortality and cost implications of complicated intra-abdominal infections in critically ill patients

Purpose: To assess risk factors for 28-day mortality and cost implications in intensive care unit (ICU) patients with complicated intra-abdominal infections (cIAIs). Methods: Single-center retrospective cohort study of prospectively collected data analysing ICU patients with a microbiologically confirmed complicated intra-abdominal infections. Results: 137 complicated intra-abdominal infections were included and stratified according to the adequacy of antimicrobial therapy (initial inadequate antimicrobial therapy [IIAT], n = 44; initial adequate antimicrobial therapy [IAAT], n = 93). The empirical use of enterococci/methicillin-resistant Staphylococcus aureus active agents and of carbapenems was associated with a higher rate of therapeutic adequacy (p = 0.016 and p = 0.01, respectively) while empirical double gram-negative and antifungal therapy did not. IAAT showed significantly lower mortality at 28 and 90 days and increased clinical cure and microbiological eradication (p < 0.01). In the logistic and Cox-regression models, IIAT and inadequate source control were the unique predictors of 28-day mortality. No costs differences were related to the adequacy of empirical therapy and source control. The empirical double gram-negative and antifungal therapy (p = 0.03, p = 0.04) as well as the isolation of multidrug-resistant (MDR) bacteria and the microbiological failure after targeted therapy were drivers of increased costs (p = 0.004, p = 0.04). Conclusions: IIAT and inadequate source control are confirmed predictors of mortality in ICU patients with complicated intra-abdominal infections. Empirical antimicrobial strategies and MDR may drive hospital costs.