Study objective: To evaluate the causes, risk factors,
and mortality rates associated with unexpected readmission to medical
and surgical ICUs.
Data sources: MEDLINE citation
review of primary articles focusing on ICU readmission or ICU outcomes
from January 1966 to June 1999, and contact with authors of primary
Study selection: Eight primary studies of ICU
readmission and eight multi-institutional ICU outcome studies that
reported ICU readmission rates were included.
extraction: We abstracted data on the methodology and design of
the primary studies, overall rates, causes, predictors, outcomes, and
measures of quality of care associated with ICU readmission.
Data synthesis: The average ICU readmission rate of 7%
(range, 4 to 14%) has remained relatively unchanged in both North
America and Europe. Respiratory and cardiac conditions were the most
common (30 to 70%) precipitating cause of ICU readmission. Patients
readmitted to ICUs had average hospital stays at least twice as long as
nonreadmitted patients. Hospital death rates were 2- to 10-times higher
for readmitted patients than for those who survived an ICU admission
and were never readmitted. Predictors of ICU readmission have been
neither well studied nor reproducible. Unstable vital signs, especially
respiratory and heart rate abnormalities, and the presence of poor
pulmonary function at time of ICU discharge appear to be the most
consistent predictors of ICU readmission. There were no consistent data
supporting the use of readmission rates as a measure of quality of
Conclusions: ICU readmission is associated with
dramatically higher hospital mortality. Unstable vital signs at the
time of ICU discharge are the most consistent predictor of ICU
readmission. Further studies focusing on processes of ICU and hospital
care are needed to determine if ICU readmission rates are a measure of
quality of care.