Summary

Although specific criteria for diagnosing the antiphospholipidsyndrome (APS) exist (the Sapporo Criteria), most physiciansare not aware these include repeat testing and documentationof either a lupus anticoagulant or medium to high levels of anticardiolipinantibody. Incorrect diagnosis of APS may result in unnecessarylong-term anticoagulation.The purpose of this studywas to determine the clinical and serological characteristics ofpatients being treated for APS and concordance with publishedcriteria. This cross-sectional study identified APS patients whowere being treated with warfarin at one of three universitybasedanticoagulation clinics. Levels of anticardiolipin antibodywere classified as low-positive if abnormal but < 40 GPL/MPLunits and medium/high-positive if = 40 units. Strength of meetingSapporo criteria was graded as definite, possible, and not meeting criteria. Of 103 cases, 97 had clinical and laboratory dataavailable. Only 10 cases (10%, 95% Confidence Interval 5 – 19)met criteria for definite APS, 16 (16%, 10 – 26) had a possible diagnosis,and 71 (73%, 63 – 81) did not meet criteria. Of 70 casesthat had abnormal anticardiolipin antibody results, only 32 (46%,34 – 58) had medium/high-positive levels. Repeat laboratorytesting was performed in only 49 cases (51%, 40 – 61). We concludethat few patients treated forAPS met Sapporo criteria. Abnormallevels of anticardiolipin antibody were frequently in thelow-positive range, and repeat testing was often absent. Aquality improvement program that includes review of cases referredfor chronic anticoagulation care is recommended to ensureappropriate testing and treatment of patients with suspectedAPS.