Table 2.

Primary, Restricted, and Sensitivity Analyses of the Effect of the Intervention.^*

Analysis and Exposure Variable	Population†	Outcome Measured	Rate Ratio (95% CI)‡	P Value
Primary
Intensivist staffing on first night	All patients	Time to ICU discharge	0.98 (0.88–1.09)	0.72
Restricted
Intensivist staffing on first night	Patients admitted at night	Time to ICU discharge	0.98 (0.84–1.13)	0.74
Sensitivity
Intensivist staffing on first night	All patients	Time to request for bed in general ward	0.97 (0.87–1.08)	0.56
Intensivist staffing on first night	All patients	Time to ICU discharge, with patients transferred to hospice facility categorized as having died	0.97 (0.87–1.09)	0.61
Cumulative proportion of nights exposed to the intervention§	All patients	Time to ICU discharge	0.92 (0.81–1.04)	0.18
100% vs. 0% intensivist staffing	Patients with all or no exposure to intervention	Time to ICU discharge	0.98 (0.86–1.12)	0.81

^*All the analyses were adjusted for APACHE III score and source of ICU admission (e.g., outside hospital, in-hospital floor, or emergency department).

^†The total population (all patients) comprised 1598 patients. A total of 970 patients were admitted at night from (5:00 p.m. through 4:59 a.m.), and 1072 patients had either all or no exposure to the intervention.

^‡In this study, the rate ratio refers to 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, such that a rate ratio greater than 1 would indicate that the intervention shortened the time to ICU discharge.

^§On each day of a patient's stay in the ICU, the cumulative exposure was calculated as the number of intervention nights divided by the total number of nights up to that day.