Analysis of risk factors and comorbid diseases in the development of thrombosis in patients with anticardiolipin antibodies.

Our objective was to identify the role of various disease states and additional risk factors in the development of thrombosis in patients with anticardiolipin antibodies (aCL). We undertook a retrospective chart review of patients with aCL (IgG or IgM titres > 20 GPL or 20 MPL by ELISA). Patients with a thrombotic event were compared to patients without thrombosis for potential risk factors: age, gender, ethnicity, hypertension (HTN), diabetes (DM), hyperlipidaemia, tobacco use and sequential aCL determinations. The role of systemic lupus erythematosus (SLE), human immunodeficiency virus (HIV), hepatitis C and renal disease was also analysed. Statistical analysis was performed using the t-test, the chi(2) test and multivariate analysis. Of the 107 patients who had moderately positive aCL (IgM and/or IgG), 53 had a thrombotic event. The patients with thrombosis were significantly older than patients without thrombosis (mean age 46.6 vs. 38.75 years, respectively, P=0.014). No significant differences in gender, race, HTN, DM, hyperlipidaemia, tobacco use or concomitant diseases were identified in the two groups. Thrombosis was more frequent in patients who were seropositive for both IgG and IgM ( P=0.027). Thrombosis was observed in equal frequencies in patients with aCL on both determinations and in patients with aCL on only one of the two determinations. In patients with aCL on two determinations a high-titre IgG aCL was associated with thrombosis. Patients with renal disease and aCL on only one of the two determinations had fewer thrombotic events ( P=0.0046). Mean aCL IgM titres were higher in thrombosis groups containing venous thromboses than in the thrombosis group with arterial thrombosis only. We concluded that risk factors for thrombosis with a single aCL determination include older age and both IgM and IgG aCL. With persistent aCL, high-titre IgG aCL was associated with thrombosis.