Assessment of the 2006 revised antiphospholipid syndrome classification criteria

Objective: To analyse antiphospholipid ( aPL) antibody- positive patients using the 2006 revised antiphospholipid syndrome ( APS) classification criteria. Methods: A descriptive study of 200 aPL- positive patients identified in a local, hospital- based registry, analysing demographic, clinical and aPL characteristics. Patients were analysed for ( 1) fulfilment of the 1999 original ( Sapporo) and 2006 revised APS classification criteria; ( 2) non- criteria aPL features ( for all aPLpositive patients, based on the 2006 revised criteria definitions); and ( 3) non- aPL thrombosis risk factors at the time of the clinical events ( for patients with APS, based on the 2006 revised criteria stratifications). Results: Of the 200 patients, 183 patients had sufficient data for analysis. Of these, 39 ( 21%) patients did not meet the laboratory requirement of the original 1999 criteria. Of 81 patients with APS who met the 1999 classification criteria, 47 ( 58%) also met the 2006 revised criteria. Of 63 asymptomatic ( no vascular or pregnancy events) aPL- positive patients who met the laboratory requirement of the 1999 classification criteria, 38 ( 60%) also met the laboratory requirement of the 2006 revised criteria. More than 50% of the patients with APS with vascular events had identifiable non- aPL thrombosis risk factors at the time of clinical events. Conclusions: Only 59% of the patients meeting the 1999 APS Sapporo classification criteria met the 2006 APS classification criteria. The revised criteria will have positive implications in APS research by way of limiting the inclusion of a heterogeneous group of patients and also by way of providing a risk- stratified approach.