Thrombotic Risk Assessment in Systemic Lupus Erythematosus: Validation of the Global Antiphospholipid Syndrome Score in a Prospective Cohort

Objective This study was performed to prospectively and independently validate the Global Antiphospholipid Syndrome Score (GAPSS), a system derived from the combination of independent risk factors for thrombosis, including antiphospholipid antibodies (aPL) and conventional cardiovascular risk factors. Methods The GAPSS was applied to 51 consecutive systemic lupus erythematosus patients, all positive for aPL and prospectively followed up for mean ± SD 32.94 ± 12.06 months. Of them, 48 were women with a mean ± SD age of 37.35 ± 12.15 years at entry. The GAPSS was calculated yearly for each patient by adding together the points corresponding to the risk factors. Results An increase in the GAPSS (entry versus last visit) was seen in patients who experienced vascular events (n = 4, mean ± SD 7.5 ± 4.36 versus 10.0 ± 5.4; P = 0.032). No changes were observed in those without thrombosis (n = 47, mean ± SD 8.28 ± 4.88 versus 7.13 ± 5.75; P = 0.24). An increase in the GAPSS during the followup was associated with a higher risk of vascular events (relative risk 12.30 [95% confidence interval (95% CI) 1.43–106.13], P = 0.004), and an increase of more than 3 points showed the best risk accuracy for vascular events (hazard ratio 48 [95% CI 6.90–333.85], P = 0.0001). The cumulative proportion of thrombosis‐free individuals was lower in patients whose GAPSS was increased by 3 or more points (P = 0.0027). Conclusion We have prospectively demonstrated that GAPSS is a valid tool for accurate prediction of vascular events in SLE patients with aPL.