Background. Central venous catheters (CVCs) continue to be used at a high rate for dialysis access and are frequently complicated by thrombus-related malfunction. Prophylactic locking with an anticoagulant, such as heparin, has become standard practice despite its associated risks. Trisodium citrate (citrate) 4% is an alternative catheter locking anticoagulant.

Methods. The objective was to prospectively study the clinical effectiveness, safety and cost of citrate 4% vs heparin locking by comparing rates of CVC exchanges, thrombolytic use (TPA) and access-associated hospitalizations during two study periods: heparin period (HP) (1 June 2003–15 February 2004) and Citrate Period (CP) 15 March–15 November 2004. Incident catheters evaluated did not overlap the two periods.

Results. There were 176 CVC in 121 patients (HP) and 177 CVC in 129 patients (CP). The event rates in incident CVC were: CVC exchange 2.98/1000 days (HP) vs 1.65/1000 days (CP) (P = 0.01); TPA use 5.49/1000 (HP) vs 3.3/1000 days (CP) (P = 0.002); hospitalizations 0.59/1000 days (HP) vs 0.28/1000 days (CP) (P = 0.49). There was a longer time from catheter insertion to requiring CVC exchange (P = 0.04) and TPA (P = 0.006) in the citrate compared with the heparin lock group. Citrate locking costs less than heparin locking but a formal economic analysis including indirect costs was not done.

Conclusion. Citrate 4% has equivalent or better outcomes with regards to catheter exchange, TPA use and access-related hospitalizations compared with heparin locking. It is a safe and less expensive alternative. Randomized trials comparing these anticoagulants with a control group would definitively determine the optimal haemodialysis catheter locking solution.