Predicted mortality for patients undergoing elective surgery was calculated using logistic regression with RAI scores as the sole independent variable. The predicted mortality for each RAI score is plotted against the observed mortality with 95% confidence intervals. The revised RAI showed significant improvement in model calibration, as demonstrated by improved c-statistic and overlap of the predicted mortality with observed mortality.
Figure 1a: Observed vs. Predicted 180-day Mortality for RAI-A Original Score in Veterans Affairs Surgical Quality Improvement Program (VASQIP; c=0.813)
Figure 1b: Observed vs. Predicted 180-day Mortality for RAI-rev Recalibrated Score in VASQIP (c=0.842)
Figure 1c: Observed vs. Predicted 30-day Mortality for RAI-rev Recalibrated Score in American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP; c=0.87)
Figure 1d: Observed vs. Predicted 30-day Mortality for RAI-C-rev Recalibrated Score in prospectively collected data at Nebraska Western Iowa Health Care System (NWIHCS; c=0.8)