Six RCTs were included in the review (n=691 patients). Sample sizes ranged from 20 to 222 patients. Trial quality was generally poor: Jadad scores ranging from 0 to 2 (median 1.5) out of a maximum of 5. There was no evidence of statistical heterogeneity in any analyses except intraoperative red blood cell transfusions (OR analysis), which showed moderate heterogeneity (I2=48%). Mean prime volume was 1519.8mL for the control group and 596.5mL for the RAP group (p<0.0001).
Intraoperative red blood cell transfusions: There was a statistically significant 64% reduction in the number of patients transfused intraoperative red blood cells in the RAP group compared with the control group (OR 0.36, 95% CI 0.13 to 0.94; four trials, n=557 patients). There was no significant difference between RAP group and control for the number of intraoperative red blood cells transfused (one trial, n=222 patients).
Total hospital stay red blood cell transfusions: There was a statistically significant 74% reduction in the number of patients transfused red blood cells over the total hospital stay in the RAP group compared with the control group (OR 0.26, 95% CI 0.13 to 0.52; two trials, n=160 patients). There was a statistically significant reduction in the total number of units of red blood cells transfused over the whole hospital stay for patients in the RAP group compared with the control group (WMD -0.60, 95% CI -0.90 to -0.31; four trials, n=294 patients).
Sensitivity analyses indicated that the results for intraoperative red blood cell transfusions were not robust to removal of single trials; removal of either one of the two trials that demonstrated the most benefits with RAP negated the statistical benefit of the pooled result.