Readmission to Surgical Intensive Care Increases Severity-Adjusted Patient Mortality

Abstract

This study aims to determine whether severity-adjusted outcomes including mortality are adversely impacted by readmission to a surgical intensive care unit (SICU) during the same hospital stay. The study included all patients admitted to the 20-bed tertiary care SICU in an urban teaching Level I trauma center and multiorgan transplant center from January 1, 1996 to December 31, 2001. This was a prospective observational study with secondary data analysis. Acute Physiology and Chronic Health Evaluation (APACHE II) and Simplified Acute Physiology (SAPS) severity scores were calculated by a clinical information system. Outcomes were extracted from a computerized data warehouse. In-hospital mortality and SICU length of stay (LOS) were measured for patients admitted and readmitted to the SICU. Of 10,840 patients admitted to the SICU, 296 (2.73%) required readmission to the SICU during the same hospital stay. The length of the original SICU stay was 4.9 +/- 6.7 days for readmitted patients compared with 3.2 +/- 6.0 days for nonreadmitted patients (p < 0.001). Readmitted patients had a higher mean APACHE II score on the day of original SICU discharge compared with nonreadmitted patients, 15.7 +/- 6.7 versus 13.8 +/- 7.1 (p < 0.001). The average APACHE II score increased from 15.7 +/- 6.7 to 18.1 +/- 8.6 between the day of SICU discharge and readmission (p < 0.001) and SAPS increased from 12.2 +/- 4.8 to 13.5 +/- 5.4 (p < 0.001). The distributions of severity-adjusted hospital mortality for both APACHE II and SAPS revealed that readmission to the SICU significantly increased mortality independent of the admission severity score. Readmission to the SICU significantly increases the risk of death beyond that predicted by the APACHE II or SAPS scores alone. Higher APACHE II and SAPS scores upon discharge from the SICU and longer SICU LOS are associated with an increased incidence of readmission to the SICU on the same hospital stay. These results may be used to optimize the timing of SICU discharge and reduce the chance of readmission to intensive care.