Time-series plots. Erythrocyte transfusion rates up to postoperative day 7. The algorithm was instituted at the beginning of the 13th interval. All odds ratio (OR), 95% CIs, and P values calculated using segmented regression modeling adjusted as described in the Statistical Analysis section. ORs before and after intervention refer to respective changes in outcome per 4-week period. OR for the intervention refers to change in outcome associated with the institution of the algorithm. (A) Entire sample: before intervention: OR, 0.96 (0.92–1.01), P = 0.08; intervention effect: OR, 0.50 (0.32–0.77), P = 0.002; and after intervention: OR, 1.04 (0.97–1.11), P = 0.23. (B) Stratified according to bleeding risk. Low bleeding risk: before intervention: OR, 0.90 (0.86–0.94), P < 0.001; intervention effect: OR, 0.51 (0.30–0.86), P = 0.01; and after intervention: OR, 1.15 (1.07–1.14), P < 0.001. High bleeding risk: before intervention: OR, 1.08 (1.03–1.15), P = 0.005; intervention effect: OR, 0.46 (0.23–0.95), P = 0.04; and after intervention: OR, 0.89 (0.81–0.98), P = 0.02.