Platelet to red cell distribution width ratio for predicting clopidogrel efficacy in patients undergoing percutaneous coronary interventions: insights from the ONSIDE-TEST study

INTRODUCTION Dual antiplatelet therapy (DAPT) with aspirin and clopidogrel remains a cornerstone of pharmacotherapy after percutaneous coronary intervention (PCI). It has been demonstrated that even up to 30% of patients receiving DAPT have inadequate response to clopidogrel, namely, high on‑treatment platelet reactivity (HPR). The platelet to red cell distribution width (P‑RDW) ratio represents an indicator of cardiovascular risk and may be related to HPR.
OBJECTIVES The aim of the present study was to establish whether the P‑RDW ratio predicts HPR in clopidogrel‑treated patients undergoing elective PCI.
PATIENTS AND METHODS This was a subanalysis of the prospective randomized‑controlled ONSIDE TEST study. A total of 70 patients were included in the analysis, of whom 12 were identified with HPR. The HPR was defined as the values above the threshold of 208 platelet reactivity units (PRU >208) by the VerifyNowP2Y12 assay.
RESULTS The P‑RDW ratio was lower in patients with HPR than in those without HPR (mean [SD], 14.37 [4.13] vs 17.734 [4.96]; P = 0.03). A logistic regression analysis showed that the P‑RDW ratio was associated with HPR (P = 0.03). Using a cut‑off level of 15.23, the P‑RDW ratio predicted HPR with
a sensitivity of 69% and specificity of 75% (odds ratio, 6.67; 95% CI, 0.561–0.890; P = 0.02; are under the receiver operating characteristic curve, 0.723).
CONCLUSIONS The P‑RDW ratio may serve as a supplementary tool for identification of patients at risk of HPR. Further studies are warranted to assess its role in planning DAPT among patients undergoing PCI.