Antiphospholipid antibodies and platelet hyperreactivity as markers for thrombosis of the hemodialysis vascular access: A correlative clinical study

Background. End-stage renal disease (ESRD) patients are maintained on renal replacement therapy for survival. Hemodialysis is the most common treatment choice for ESRD patients, yet it is not free of complications. While bleeding is a very common problem in ESRD due to the effects of uremia and heparin, hemodialysis vascular access thrombosis (VAT) is the most morbid and costly complication in ESRD patients. Hypercoagulability is a major risk factor for VAT without an identifiable anatomic lesion. However, in most patients, the cause of hypercoagulability cannot be identified despite clinical suspicion.; Purpose. In this research project, the occurrence of antiphospholipid antibodies (aPAs) and platelet hyperreactivity were investigated for a possible role in the hypercoagulability of ESRD and VAT.; Study design. Forty-three local ESRD patients with arteriovenous fistulas or grafts were enrolled in the study. Several aPA ELISAs were used to measure the titers of anticardiolipin antibodies and antiphosphatidylserine antibodies (IgM, IgG, and IgA isotypes) in patient sera. Nationally recognized aPA reference intervals were used. Platelet function and hypercoagulability were assessed in patient blood using the Baumgartner platelet adhesion apparatus, platelet aggregation, and thromboelastography. A double-blinded comprehensive patient medical chart review of the history of VAT was also conducted.; Results. APAs were detected in 18 patients (42%), of whom, ten patients (26%) had persistent aPAs for over eight weeks, and eight patients had "moderate" titers of IgM and/or IgG aPAs (21%). Twenty-one patients (49%) demonstrated platelet hyper-adhesiveness as revealed in the platelet adhesion assay.; Statistical analyses. A nonparametric two-factor ANOVA was performed to compare the experimental and clinical data. A Kaplan-Meier analysis of hemodialysis vascular access survival was also conducted to examine the aPA status and platelet hyper-adhesiveness as predictors of access survival. Conclusions. This study did not show any evidence for association of aPAs and the history of VAT in these patients. However, the study showed a significant correlation between increased platelet adhesiveness and shortened survival of the primary hemodialysis vascular access. This finding may have significant clinical implications for risk assessment and prevention of VAT, and platelet adhesion testing may become a useful clinical tool for identification of high-risk patients.