Background and aims The evaluation of thrombotic and pregnancy risks associated with antiphospholipid antibodies (aPLs) in individual patients is challenging. Our objective was to identify potential clinical and epidemiological predictors of thrombosis and pregnancy morbidities in a large Chinese antiphospholipid syndrome (APS) cohort.

Methods This cohort included 177 consecutive APS patients and 146 asymptomatic aPLs control patients who attended the rheumatology clinic at People’s Hospital of Beijing University Health Science Centre. All APS patients fulfilled the 2006 revised criteria APS. All control patients had at least one persistent positive aPLs without any other criteria APS manifestations. When assessing risk factors associated with pregnancy morbidities, only reproductive age (age <45) female controls were used. Chi-squared or Fisher’s exact test univariate analysis and multivariable logistic regression analyses were used to assess association between different clinical and epidemiological risk factors and clinical manifestations.

Results Of the 177 APS patients, 134 (75.7%) were women with a mean age of 43. 5 (S.D. 16). When comparing to controls, risk factors associated with thromboembolic events included: Raynaud’s phenomenon (odds ratio (OR)=2.371, 95% Confidence interval (CI) 1.039–5.637, p=0.0462), hypertension (OR=1.829, 95% CI 1.114–3.05, p=0.022), and smoking (OR=3.941, 95% CI 1.816–8.799, p=0.0004). Age, hyperlipidemia, diabetes, hypocomplementemia, and thrombocytopenia did not demonstrate significant association with thrombosis. None of the analysed clinical characteristics showed significant association with pregnancy morbidities. A high frequency of thrombocytopenia and hypocomplementemia were observed in both APS patients and control patients with persistent +aPLs.

Conclusions Smoking, Raynaud’s phenomenon, and hypertension are potential predictors of thromboembolic events in +aPLs Chinese patients.