thromboses per 100 patient-years in an average of 3 years of followup, but the population studied also included APS patients with vascular thrombosis before the study period (6). To date, no study has specifically addressed thrombosis prophylaxis with ASA or any other medication during nonpregnancy periods. Wahl et al used a Markov decision analysis to evaluate the prophylactic role of ASA in SLE. That model suggested that primary thrombosis prophylaxis with aspirin is beneficial to all patients with SLE, especially patients with aPL, and the authors suggested confirmation in randomized trials (7).
The limitations of our study are the retrospective nature of the data collection, the unconfirmed compliance with ASA treatment, the fact that relatively few confounders were studied, and the fact that all hospitals providing patients for this study were tertiary referral centers, creating a potential bias toward patients with more severe disease.
It is well known that aPL can be asymptomatic over years or it can result in serious, if not fatal, thrombotic events. Currently, there is no way to predict when or which patients will develop vascular thrombosis. Also, we were not able to demonstrate any risk factor for vascular thrombosis, such as age or aPL profile. Our data suggest that there is a high incidence of subsequent thrombosis in APS patients who present only with pregnancy loss and that aspirin may be indicated for thrombosis prophylaxis in this subgroup. Despite the retrospective nature of the data collection, our study results provide the first indication of a beneficial role of ASA in this subgroup of APS patients.