Validity of the 2023 ACR/EULAR APS classification criteria to pediatric primary APS: inputs from a systematic literature review

Objectives The 2023 ACR/EULAR antiphospholipid syndrome (APS) classification criteria have been introduced and validated in adult populations; however, data on their performance in pediatric APS remain limited. The present study aims to apply the 2023 EULAR/ACR classification criteria to a cohort of pediatric patients with primary APS identified through a systematic review of the literature. Methods A systematic literature review was conducted to identify primary pediatric APS. Individual patient data were extracted. A two-stage individual participant data–style random-effects meta-analysis was performed to estimate the pooled sensitivity of the APS scoring systems. Results A total of 118 studies were included, comprising 148 pediatric patients with primary APS. Thrombotic events were reported in 93.2% of patients, while non-thrombotic manifestations occurred in 56.8%; the most frequent extra-thrombotic manifestation was thrombocytopenia (29%). Overall, the 2006 Sapporo criteria reached a sensitivity of 91.2% (95% CI: 85.4–95.2), while the 2023 ACR/EULAR APS classification criteria of 83.1% (95% CI: 76.2–88.3). Most patients who did not satisfy the new criteria set failed to meet the laboratory domains. Conclusion The 2023 ACR/EULAR APS classification criteria demonstrate suboptimal sensitivity when applied to pediatric primary APS. While the inclusion of non-thrombotic manifestations improved the classification of pediatric APS patients, limitations remain, particularly regarding laboratory antiphospholipid antibody thresholds and the exclusion of some pediatric-relevant clinical features, confirming the incomplete overlap between pediatric and adult-onset APS. These findings highlight the need for pediatric-specific APS classification criteria to improve disease characterization and research in this population.