A randomized trial of minidose warfarin for the prevention of late malfunction in tunneled, cuffed hemodialysis catheters

Background. Minidose warfarin (1 mg/day) has been associated with a 74% red uction in the thrombosis rate of central venous catheters used in oncology patients. To determine the efficacy of minidose warfarin on late malfunctio n caused by thrombosis or fibrin sheath formation in tunneled, cuffed cathe ters (TCC) used for hemodialysis (HD), we performed a randomized, placebo-c ontrolled trial. Methods. One hundred five chronic IID patients with TCCs were initially ran domized. Oi these, 85 (warfarin 41 and placebo 44) completed the first two weeks of the protocol and were followed for the first year of TCC life or u ntil TCC removal. Results. Sixteen TCCs failed with late TCC malfunction, eight in each group . In a multivariate analysis, there was no significant effect of warfarin o n thrombosis-free TCC survival or time to the first urokinase (UK) instilla tion for incipient thrombosis. The presence of a low hemoglobin (Hgb; < 10. 5 g/dL) or a low international normalized ratio (INR; <1.00) was significan tly associated with a higher risk of late TCC malfunction (RR 5.2 and 4.0, respectively), a higher risk of incipient TCC thrombosis requiring UK: (RR 2.0 and 2.8, respectively), and higher rates of UK dosing. Diabetics had a 3.6-fold higher risk of late TCC malfunction and a twofold higher risk of i ncipient thrombosis requiring UK, although these findings were not statisti cally significant. Aspirin use, race, age, number of hospitalizations, eryt hropoietin dose, intradialytic heparin dose, serum albumin, and the number of episodes of TCC-associated infection were not significantly associated w ith late TCC malfunction. Conclusions. Thrombosis prophylaxis using fixed minidose warfarin is not ef ficacious in TCCs used for HD. However, the present data suggest improved T ee survival in patients with an INR >1.00. Patients with diabetes and those with a low Hgb or INR have a higher risk of late TCC malfunction.