ICU-Acquired Infection Is the Main Driver of Resource Utilization, Independent of Antimicrobial Resistance

Healthcare-associated infections (HAIs) are frequent in intensive care units (ICUs) and are associated with substantial clinical and economic burden. However, the independent contribution of antimicrobial resistance (AMR) beyond the occurrence of infection remains uncertain.

We conducted a retrospective cohort study including 802 adult ICU admissions in a tertiary university hospital. Patients were classified into three groups: no ICU-acquired HAI (n=666), HAI without AMR (n=105), and HAI with AMR (n=31). Primary outcomes were ICU length of stay (LOS) and hospital costs; hospital mortality was analysed as a secondary outcome. Generalized linear models adjusted for age, sex, Simplified Acute Physiology Score II (SAPS II), and comorbidities were used. A restricted analysis among infected patients evaluated the independent association of AMR.

ICU-acquired HAI occurred in 17% of patients, with AMR identified in 3.9%. ICU LOS increased across groups (6 vs 19 vs 21 days; p<0.001). In adjusted analyses, ICU LOS was 7.6 days in patients without HAI, 21.7 days in patients with HAI without AMR, and 30.3 days in those with AMR. Adjusted hospital costs were €29,105, €60,065, and €70,164, respectively. In analyses restricted to infected patients, AMR was not independently associated with ICU LOS or hospital costs.

ICU-acquired infection was the primary driver of increased ICU length of stay and hospital costs. After adjustment for severity and comorbidity burden, antimicrobial resistance was not independently associated with additional resource utilization among infected patients. These findings highlight infection prevention as a priority for reducing ICU burden, alongside antimicrobial stewardship strategies.