Evaluation of anticoagulation in patients with antiphospholipid syndrome

Abstract

The quality of anticoagulation therapy in patients with antiphospholipid syndrome (APS) was evaluated. The high risk of unnecessary anticoagulation and recent changes in the recommended International Normalized Ratio (INR) target range prompted a performance-improvement initiative to improve the care of patients with APS within the University of Iowa Hospitals and Clinics internal medicine and family medicine anticoagulation clinics. Twenty-three patients with an initial diagnosis of APS were evaluated through chart review to determine the anticoagulation indication, occurrence of thromboembolic events, and INR target range. Confirmation of APS diagnosis was made using Sapporo criteria. Recommendations were made to the patients' physicians for confirmatory APS testing and changes in the anticoagulation regimen. INR target ranges were 2.0-3.0, 2.5-3.5, and 2.5-3.0 for 57%, 39%, and 4% of patients, respectively. Only 6 (26%) of the 23 patients met Sapporo criteria for a definite diagnosis of APS. Of the 17 patients (74%) who did not meet these criteria, 8 (47%) had another indication for indefinite anticoagulation. Repeat APS testing was indicated for 7 patients, 5 of whom met Sapporo criteria for APS. A lower target INR range of 2.0-3.0 was determined appropriate for 6 (26%) of the 23 patients evaluated. A majority of patients with an initial diagnosis of APS did not meet criteria for a definite diagnosis of APS. Of those patients, approximately half had another indication for long-term anticoagulation, and one third were receiving warfarin dosages based on an INR target range that was higher than clinically indicated.