Abstract 18 — Standardized Mortality Ratio and Risk Factors for Mortality and Recurrence in Hong Kong Chinese Patients with Antiphospholipid Syndrome

Background To report standardized mortality ratio (SMR) and assess risk factors for mortality and recurrence in Hong Kong Chinese patients with antiphospholipid syndrome (APS). Methods Patients followed up in 16 public hospitals in Hong Kong were identified by the Hospital Authority Clinical Data Retrieval System (CDARS) using the ICD-10 diagnostic code of APS. Their diagnoses were verified using the 2006 modified consensus criteria (1) for APS. The mortality, thrombosis recurrence rate and their associated risk factors were studied by Kaplan-Meier method and Cox Regression. Results Four hundred twenty-three Chinses APS patients were identified. Among them, 288 patients fulfilled the 2006 criteria for APS and were classified as definite APS, while 135 patients had probable APS. APS was primary in 204 patients and secondary in 219 patients. On presentation, 369 patients had thrombotic events. Arterial thrombosis occurred in 177 patients and venous thrombosis occurred in 189 patients. Obstetric morbidities occurred in 77 patients. Twenty three patients had both obstetric and thrombotic events. Over a mean follow-up of 9.7±7.2 years, 75 (17.7%) patients succumbed. The age and sex adjusted SMR relative to general population was 4.34[95% CI 3.44-5.41]. In thrombotic APS patients, mortality was associated with age [Formula: see text]60 years at diagnosis (HR 5.30 [95% CI 3.11-9.03]; p<0.001), presence of arterial hypertension (HR 1.89 [95% CI 1.11-3.19]; p =0.018), and presence of arterial thrombosis (HR 1.81 [95% CI 1.06-3.10]; p=0.031). Recurrence of thrombosis occurred in 89 (21%) patients (15% arterial, 5.2% venous). Recurrence of thrombosis was found to be associated with triple positive antibodies (HR 2.71 [95% CI 1.15-6.42]; p=0.023) independent of other risk factors in a multivariate model. Conclusion Increased mortality rate was observed in Chinese APS patient, with older age at diagnosis, presence of arterial hypertension and arterial thrombosis being independent risk factors for mortality. Recurrence of thrombotic events was not uncommon and associated with the presence of triple positive aPL antibodies.