IgM anticardiolipin antibodies are associated with stenosis of vascular access in hemodialysis patients but do not predict thrombosis

Aim: The prevalence of anticardiolipin antibodies (ACA) is elevated amongst hemodialysis patients as compared with the general population. Previous st udies have disagreed as to whether the presence of ACA represents a risk fa ctor for access thrombosis. Other risk factors for access thrombosis (decre ased blood flow, elevated venous pressure) have also been described. Materi als and methods: We performed a combination retrospective and prospective c ohort study of a single outpatient dialysis unit to assess the association between these potential risk factors and access thrombosis. ACA, access blo od flow, presence of stenosis, and venous pressures were measured in 100 pa tients. Information on episodes of access thrombosis was gathered for 12 mo nths prior to and 12 months after ACA measurement. Results:, ACA were prese nt in 19% of patients with equal numbers of IgG- and IgM-ACA. The presence of IgM-ACA was significantly associated with the use of aspirin and the pre sence of stenosis by Doppler at the time of ACA testing (p < 0.05). A logis tic regression model was used to estimate the association between clinical factors and access thrombosis. In this multivariate analysis, the presence of access stenosis and a history of access thrombosis were both significant ly associated with the development of access thrombosis. Adjusted for these variables, neither IgG-nor IgM-ACA was significantly associated with acces s thrombosis. The presence of an ACA was not associated with episodes of ac cess thrombosis in either the prospective or retrospective analyses. Conclu sion: Further investigation is required to determine if the association bet ween aspirin use and IgM-ACA, or of IgM-ACA and access stenosis, has implic ations for underlying pathogenetic mechanisms of access stenosis.