Incidence rate and variable cost of nosocomial infections in different types of intensive care units

Abstract

Objective: Nosocomial infection (NI) is one of the most serious healthcare issues currently influencing healthcare costs. This study estimates the impact of NI on costs in intensive care units (ICUs).

Design: Prospective surveillance by a retrospective cohort study.

Setting: A medical ICU, a surgical ICU, and a mixed medical and surgical ICU in a large tertiary referral medical center.

Methods: Surveillance for NIs was conducted for all patients admitted to adult ICUs from 2003 through 2005. Retrospective chart review was conducted for each patient. The generalized linear modeling approach was used to assess the relationship of NIs to the increase in variable costs in individual ICUs and in all ICUs.

Results: A total of 401 NIs occurred in 320 of 2,757 screened patients. The incidence rate was 12.1% in the medical ICU, 14.7% in the surgical ICU, and 16.7% in the mixed medical and surgical ICU (P>.05). All of the mean variable costs were significantly higher for patients with NI than they were for patients without NI, after controlling for covariates. The medical ICU had the greatest increase in mean cost ($13,456, which was 3.52 times [95% confidence interval {CI}, 2.94-4.22 times] the mean cost for patients without NI), followed by the mixed medical and surgical ICU ($6,748, which was 2.74 times [95% CI, 2.33-3.22 times] the mean cost for patients without NI) and the surgical ICU ($5,433, which was 2.46 times [95% CI, 1.99-3.05 times] the mean cost for patients without NI). Mean cost increases according to the site of NI were $6,056 for bloodstream infection (2.36 times [95% CI, 1.97-2.84 times] the mean cost for patients without NI), $4,287 for respiratory tract infection (1.91 times [95% CI, 1.57-2.32 times] the mean cost for patients without NI), $1,955 for urinary tract infection (1.42 times [95% CI, 1.18-1.72 times] the mean cost for patients without NI), and $1,051 for surgical site infection (1.23 times [95% CI, 0.90-1.68 times] the mean cost for patients without NI).

Conclusions: The medical ICU had the lowest rate of NI and the largest excess costs, the surgical ICU had the lowest excess costs, and the mixed medical and surgical ICU had the highest rate of NI. The cost is largely attributable to bloodstream infection and respiratory tract infection.