The Incidence and Methods for Detecting Aspirin Resistance in Pediatric Patients

Since aspirin resistance is rarely assessed in pediatric patients and thrombosis might cause damage in vital organs, such as the myocardium or brain, we aimed to determine its incidence and the pivotal role of routine screening. The point-of-care test by platelet function analyzer (PFA-200) and bedside bleeding time (BT) was compared to standard whole blood impedance aggregometry (IA), the time-consuming and sophisticated assays. This single-center cross-sectional study was investigated in Thai children (≤15 years). All participants received at least five-day administrations of aspirin (3 to 5 mg/kg/day or equivalent to a single tablet of 81 mg) for any prior thrombotic risks. Platelet aggregation >5 ohms on IA with 0.5 mM arachidonic acid, closure time <180 seconds on collagen/epinephrine PFA-200, and modified Ivy BT ≤7 minutes, defined resistance. Of 37 patients, 2.7% had confirmed aspirin resistance to IA. Despite the 100% sensitivity, PFA-200 showed higher specificity than BT (83.3% vs 36.1%). However, both were not comparable (exact McNemar P < 0.05), with a slight/fair reliability (ĸ=0.215 vs ĸ=0.030 respectively). Aspirin resistance is uncommon in Thai children. Routine screening is discouraged but recommended only in cases with recurrent thrombosis despite good aspirin compliance or the presence of resistant risk factors. Although the gold standard IA could not be replaced, the rapid assay of PFA-200, not bedside BT, can potentially be considered a point-of-care alternative screening test to detect aspirin resistance in children.