Recent studies have shown that intensivist physicians improve patient outcomes in intensive care units (ICUs), leading to the assumption that there may be a dose-response effect, with greater exposure to intensivists being associated with even better outcomes. This assumption has led to many ICUs, including one third of academic ICUs in the United States, using in-hospital intensivist staffing at night.
Studies conducted before and after implementation of nighttime intensivist staffing have seen mixed results. Noting the limitations of observational studies and concerns about the costs of nighttime intensivist staffing, researchers recently conducted a randomized clinical trial at a US academic medical ICU that had high-intensity daytime staffing and continuous coverage by medical residents. They reported study results online in the New England Journal of Medicine [doi:10.1056/NEJMoa1302854]. The results were published to coincide with presentations at an American Thoracic Society meeting.
The SUNSET-ICU (Study to Understand Nighttime Staffing Effectiveness in a Tertiary Care ICU) was conducted in the medical ICU of the Hospital of the University of Pennsylvania. The trial compared nighttime staffing with in-hospital intensivists plus the usual complement of medical students (intervention) with nighttime staffing with in-hospital residents alone (control). Nighttime was defined as 7:00 pm to 7:00 am.
The main study outcome was patients’ length of stay in the ICU. Secondary outcomes included patients’ length of stay in the hospital, ICU and in-hospital mortality, discharge disposition, and rates of readmission to the ICU.
The study included 352 nights, half of which (n=175) were randomly assigned to the intervention; nighttime intensivists staffed 95% (n=166) of the intervention nights. Of the 1598 patients included in the analysis, 61% (n=970) were admitted at night. The mean APACHE III (Acute Physiology and Chronic Health Evaluation) score was 67 (scores range from 0 to 299, with higher scores indicating more severe illness), and median length of stay in the ICU was 52.7 hours. A total of 381 patients died in the hospital, 18% of whom (n=293) died in the ICU.
Exposure to nighttime intensivist staffing was greater for patients admitted on intervention days compared with patients admitted on control days (median 100% of nights vs median, 0%; P<.001). However, there was no significant effect of intensivist staffing on the night of admission or on length of stay in the ICU. Rate ratio for ICU discharge was 0.98 (95% confidence interval, 0.88-1.09; P=.72). Rate ratio was defined as the instantaneous rate of discharge from the ICU in the intervention group divided by the instantaneous rate of discharge from the ICU in the control group; thus, a rate ratio >1 would indicate that the intervention shortened the time to ICU discharge.
Nighttime intensivist staffing also had no significant effect on the length of stay in the hospital (median, 174 hours in the intervention group vs 166 hours in the control group) or on ICU mortality (19% in the intervention group vs 18% in the control group), hospital mortality (25% vs 23%), readmission to the ICU within 48 hours of discharge among ICU survivors (5% vs 3%), or discharge to home (39% vs 40%).
In summary, the researchers stated, “In an academic medical ICU in the United States, nighttime in-hospital intensivist staffing did not improve patient outcomes.”