Intensive care unit length of stay: recent changes and future challenges

Abstract

Objective: To compare case-mix adjusted intensive care unit (ICU) length of stay for critically ill patients with a variety of medical and surgical diagnoses during a 5-yr interval.

Design: Nonrandomized cohort study.

Setting: A total of 42 ICUs at 40 US hospitals during 1988-1990 and 285 ICUs at 161 US hospitals during 1993-1996.

Patients: A total of 17,105 consecutive ICU admissions during 1988-1990 and 38,888 consecutive ICU admissions during 1993-1996.

Measurements and main results: We used patient demographic and clinical characteristics to compare observed and predicted ICU length of stay and hospital mortality. Outcomes for patients studied during 1993-1996 were predicted using multivariable models that were developed and cross-validated using the 1988-1990 database. The mean observed hospital length of stay decreased by 3 days (from 14.8 days during 1988-1990 to 11.8 days during 1993-1996), but the mean observed ICU length of stay remained similar (4.70 vs. 4.53 days). After adjusting for patient and institutional differences, the mean predicted 1993-1996 ICU stay was 4.64 days. Thus, the mean-adjusted ICU stay decreased by 0.11 days during this 5-yr interval (T-statistic, 4.35; p < .001). The adjusted mean ICU length of stay was not changed for patients with 49 (75%) of the 65 ICU admission diagnoses. In contrast, the mean observed hospital length of stay was significantly shorter for 47 (72%) of the 65 admission diagnoses, and no ICU admission diagnosis was associated with a longer hospital stay. Aggregate risk-adjusted hospital mortality during 1993-1996 (12.35%) was not significantly different during 1988-1990 (12.27%, p = .54).

Conclusions: For patients admitted to ICUs, the pressures associated with a decrease in hospital length of stay do not seem to have influenced the duration of ICU stay. Because of the high cost of intensive care, reduction in ICU stay may become a target for future cost-cutting efforts.