The Dual Anti Platelet Therapy (DAPT) Score does not Predict Ischemic or Bleeding Events in ADAPT-DES

Background: The duration of dual antiplatelet therapy (DAP) after percutaneous coronary intervention (PCI) remains in dispute, particularly when extended beyond 12 months. The Dual Anti Platelet Therapy (DAPT) Score attempted to identify patients who can benefit the most from such extended therapy.
Objective: To assess the performance of the DAPT risk score in the Assessment of Dual Anti Platelet Therapy with Drug Eluting Stents (ADAPT-DES) registry and to test the utility of additional predictors of events on its performance.
Methods: Patients free of death and ischemic or hemorrhagic events after 1 year of DAP post PCI were analyzed. The DAPT score was calculated for each patient and comparisons were made according to median score (>2) in DAPT trial. ROC for the DAPT score were built for ischemic (myocardial infarction [MI] or stent thrombosis [ST]) and clinically relevant bleeding (CB). High-platelet reactivity (HPR) was added to ischemic model and HPR, chronic oral anticoagulation therapy, history of anemia and baseline hemoglobin were added to bleeding model.
Results: Among the 8,582 patients enrolled in ADAPT-DES, 5,397 qualified for this analysis. The DAPT score had moderate discrimination for MI or ST (c-statistic=0.615, compared with 0.68 in DAPT trial) and adequate calibration (P_HL=0.41). The addition of HPR insignificantly improved discrimination for ischemic events to 0.628. The DAPT score was very ineffective in predicting bleeding (c-statistic=0.508 compared with 0.66 in the DAPT trial) but had adequate calibration (P_HL=0.11). The addition of HPR and other bleeding correlates significantly improved the discrimination for bleeding to 0.606. Between 1 and 2 years, ischemic or hemorrhagic events occurred in 413 and 124 patients, respectively. Patients with higher scores had significantly higher rates of ischemic events and death than patients with lower scores, but similar rates of bleeding and need for blood transfusion. There was no significant interaction between continuation of DAP and clinical events.
Conclusions: The DAPT score cannot inform which event-free patients at 1 year after PCI would benefit most from continued DAP for an additional 1 year in the ADAPT-DES registry.