Validity of the global anti-phospholipid syndrome score to predict thrombosis: a prospective multicentre cohort study

Objective. To investigate the validity of the global APS score (GAPSS) to predict thrombosis in patients with autoimmune diseases. Methods. This prospective cohort study included consecutive patients with aPL or SLE. aPL, aPS-PT and GAPSS were determined. A Cox proportional hazards model assessed the validity of GAPSS and identified other potential independent predictors of thrombosis. Results. One hundred and thirty-seven patients [43.5 (S.D. 15.4) years old; 107 women] were followed up for a mean duration of 43.1 (S.D. 20.7) months. Mean GAPSS was significantly higher in patients who experienced a thrombotic event compared with those without [10.88 (S.D. 5.06) vs 8.15 (S.D. 5.31), respectively, P = 0.038]. In univariate analysis, age [hazard ratio (HR) = 1.04 (95% CI 1.01, 1.08)] and GAPSS above 16 [HR = 6.86 (95% CI 1.90, 24.77)] were each significantly associated with thrombosis during follow-up, while history of arterial thrombosis [HR = 2.61 (95% CI 0.87, 7.82)] failed to reach significance. Among aPL assays, IgG aPS/PT-a component of the GAPSS-was significantly associated with thrombosis [HR = 2.95 (95% CI 1.02, 8.51)]. In multivariate analysis, GAPSS above 16 remained the only significant predictor of thrombosis [HR = 6.17 (95% CI 1.70, 22.40)]. Conclusion. This first external validation study confirmed that GAPSS can predict thrombosis in patients with aPL and associated autoimmune diseases.