Are the 2023 ACR/EULAR classification criteria a step forward in the management of antiphospholipid syndrome? A literature-based and clinical practice appraisal.

Antiphospholipid syndrome (APS) is an autoimmune disease (AID) without defined diagnostic criteria, but having classification criteria, as happens in most AID. Until 2023, we were using 2006 Sydney classification criteria. Although they had a research purposes, in the real life they have been used as a diagnostic tool, equating classification with diagnostic. From July 2023, these criteria were revisited by American College of Rheumatology and European League Against Rheumatism (ACR/EULAR) panel of experts. This recently reported set of classification criteria underlie that only should be used for research purposes. They prioritises specificity ̵ 99 % ̵ at the cost of sensitivity ̵ 84 % ̵ ACR/EULAR criteria consider 6 clinical and 2 laboratory domains. Although new clinical items have been included, improving overall the inclusion of patients and, indirectly diagnosis, i.e., thrombocytopenia, cardiac valvular involvement and microvascular thrombosis, a remarkable number of patients with putative aPL-related disorders could leave out of classification as having APS, and in the real life, losing the opportunity to manage them appropriately. Consequently, these patients will be prone to suffer new events, thrombotic or obstetric, as have been already demonstrated. This manuscript focuses on the pros and cons of the clinical and laboratory domains of these new criteria and their impact not only on the clinical point of view, but also in the APS research field. Using 6 clinical cases, we provide readers with a sense of diagnostic certainties and uncertainties, and their shortcomings in the context of the ACR/EULAR APS classification.