Objective: Tunneled hemodialysis catheters (caths) often fail as a result of luminal obstructive thrombus or formation of a fibrin sheath at the tip. Anecdotal and non-randomized studies have indicated that aspirin (A) and/or warfarin (W) can prolong cath patency. We examined the effect of chronic usage of either A or W on primary cath patency.
Material and methods: A prospective cross-sectional monitoring of cath patency was conducted over a 3-year period. Patients were grouped according to their long-term usage of either A (325 mg daily) or W. Patients on neither medication served as a control (C). The end point of the study occurred at cannulation of the patients' arteriovenous fistulae, when there was development of cath-related bacteremia or when there was inability to maintain a blood flow of 250 ml/min.
Results: Sixty-three patients with a mean age of 57 +/- 15 years completed the study. There were 21 patients in the A group, 11 in the W group and 31 in the C group. Cath survival was 91%, 73% and 29% at 120 days for the A, W and C groups, respectively (A vs C, p < 0.0001; W vs C, p < 0.0001; A vs W, p = NS). The mean durations of cath patency were 114 +/- 18, 111 +/- 17 and 68 +/- 37 days for the A, W and C groups, respectively (A vs C, p < 0.0001; W vs C, p < 0.0001; A vs W, p = NS). Gastrointestinal (GI) bleeding complication rates were 24%, 18% and 0% for the A, W and C groups, respectively (A vs C, p = 0.02; W vs C, p = 0.02; A vs W, p = NS). The relative risk of GI bleeding associated with aspirin was 0.71 [95% confidence interval (CI) 0.11-4.4, p = 0.7] but among elderly aspirin users it was 1.14 (CI 1.0-1.3, p = 0.008).
Conclusion: Both aspirin and warfarin are equally effective at prolonging cath patency but their routine use for failing caths cannot be unequivocally recommended because of the increased risk of GI bleeding. Further prospective and randomized studies are called for.