Prediction of in-hospital bleeding in acutely ill medical patients: External validation of the IMPROVE bleeding risk score

Pharmacological thromboprophylaxis slightly increases bleeding risk. The only risk assessment model to predict bleeding in medical inpatients, the IMPROVE bleeding risk score, has never been validated using prospectively collected outcome data.We validated the IMPROVE bleeding risk score in a prospective multicenter cohort of medical inpatients. Primary outcome was in-hospital clinically relevant bleeding (CRB) within 14 days of admission, a secondary outcome was major bleeding (MB). We classified patients according to the score in high or low bleeding risk. We assessed the score's predictive performance by calculating subhazard ratios (sHRs) adjusted for thromboprophylaxis use, positive and negative predictive values (PPV, NPV), and the area under the receiver operating characteristic curves (AUC).Of 1155 patients, 8 % were classified as high bleeding risk. CRB and MB within 14 days occurred in 0.94 % and 0.47 % of low-risk and in 5.6 % and 3.4 % of high-risk patients, respectively. Adjusted for thromboprophylaxis, classification in the high-risk group was associated with an increased risk of 14-day CRB (sHR 4.7, 95 % confidence interval [CI] 1.5-14.5) and MB (sHR 4.9, 95%CI 1.0-23.4). PPV was 5.6 % and 3.4 %, while NPV was 99.1 % and 99.5 % for CRB and MB, respectively. The AUC was 0.68 (95%CI 0.66-0.71) for CRB and 0.73 (95%CI 0.71-0.76) for MB.The IMPROVE bleeding risk score showed moderate to good discriminatory power to predict bleeding in medical inpatients. The score may help identify patients at high risk of in-hospital bleeding, in whom careful assessment of the risk-benefit ratio of pharmacological thromboprophylaxis is warranted.