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.