Abstract and Introduction
Abstract
Background Little other than subjective judgment is available to help clinicians determine when a patient should be transferred out of the intensive care unit.
Objective To assess whether remaining in the intensive care unit longer than judged to be medically necessary is associated with increased 30-day mortality.
Methods This prospective, observational cohort study was performed in a 13-bed, closed-model, adult medical intensive care unit of a county-owned, university-affiliated hospital that often has difficulty transferring patients to general care areas because of a lack of available beds. Analysis included all 2401 survivors of intensive care from the study period. Delay in discharge from the intensive care unit was defined as time elapsed between the request for transfer and the actual transfer. Logistic regression was used to assess the association of discharge delay with 30-day mortality, adjusting for demographics, comorbid conditions, type and severity of acute illness, care limitations in the unit, and other potential confounding variables. Nonlinear relationships with continuous variables were modeled with restricted cubic splines.
Results Overall, 30-day mortality was 10.1%. Mean discharge delay was 9.6 (SD, 11.7) hours; 9.9% had a discharge delay exceeding 24 hours. The relationship of 30-day mortality to discharge delay was statistically significant and U-shaped, with the nadir at 20 hours.
Conclusions These data indicate an optimal time window for patients to leave the intensive care unit, with increased mortality not only if they leave earlier but also if they leave later than this optimal timing.
Introduction
Little other than subjective clinical judgment is available to help clinicians determine when a patient should be transferred out of the intensive care unit (ICU). The criterion of no longer requiring care that can be supplied only in the ICU seems straightforward to apply for mechanical ventilation and vasopressors, but less so for many interventions that are used in ICUs but are often performed outside of them as well. The decision about the need for ICU nursing care is largely subjective. As in other domains of clinical judgment in the ICU, large individual variation between physicians is likely. In addition, bed availability can influence when patients leave the ICU. Admissions when the ICU is fully occupied can result in patients being transferred out before the physician would like, whereas limited availability of beds in step-down areas can lead to transfer occurring later than desired.
Some evidence indicates excess mortality among patients transferred out of the ICU prematurely. We are unaware of any data assessing outcomes associated with remaining in the ICU longer than appears medically required; such delays may increase mortality rates by prolonging the risk of ICU-acquired complications.
Our goal was to assess how the timing of transfer out of ICU influences mortality. We were able to study the consequence of remaining in the ICU longer than the treating physicians deemed to be medically indicated because, owing to frequently inadequate availability of beds in the general care areas, patients in our ICU commonly experience such transfer delays. We hypothesized that delays in transferring patients out of the ICU due to lack of available beds in step-down units would increase mortality.