Analysis of Platelet Function Testing in Children Receiving Aspirin for Antiplatelet Effects

Area of Science:

• Pediatric Cardiology
• Pharmacology
• Clinical Chemistry

Background:

• Aspirin (ASA) is a primary antiplatelet therapy for pediatric conditions.
• The VerifyNow Aspirin Test® (VN) measures platelet response to ASA.
• Manufacturer guidelines define therapeutic effect as ≤549 aspirin reaction units (ARU).

Purpose of the Study:

• To evaluate the incidence of ASA biochemical resistance in children.
• To determine the association between VN results and thrombotic/bleeding events.
• To assess the optimal ARU cutoff for predicting ASA resistance in pediatric patients.

Main Methods:

• Observational analysis of 195 children (<18 years) undergoing initial VN testing (2015-2020).
• Primary outcome: proportion of patients with ASA resistance (>549 ARU).
• Secondary outcomes: incidence of thrombotic/bleeding events within 6 months in 113 patients on ASA monotherapy.

Main Results:

• ASA biochemical resistance was detected in 14.4% of children.
• Patients experiencing thrombotic events had significantly higher mean VN results (516 vs 465 ARU).
• VN ASA results ≥500 ARU independently predicted increased thrombosis risk (p<0.01).

Conclusions:

• The VerifyNow Aspirin Test® identifies significant ASA biochemical resistance in pediatric patients.
• An initial VN ASA result of ≥500 ARU, not ≥550 ARU, is linked to higher thrombosis odds.
• The established 550 ARU cutoff for ASA platelet inhibition may require reevaluation in children.