Warfarin not useful for prophylaxis of catheter-related thrombosis

Compared with no warfarin, prophylactic warfarin was not associated with a reduction in symptomatic catheter-related or other thrombosis in people with cancer.

“Our findings show that warfarin does not have a useful role in the prophylaxis of catheter-related thrombosis,” the researchers wrote. “These findings only add to the assertion that the time has come to move on from warfarin for thromboprophylaxis in patients with cancer.”

In this international, randomized controlled trial, researchers used data from 68 clinical centers on 1,590 patients with cancer aged 16 years or older. Patients were receiving chemotherapy through central venous catheters.

Physicians who were uncertain of the benefits of warfarin for thromboprophylaxis randomly assigned participants to either no warfarin, fixed-dose warfarin 1 mg per day or dose-adjusted warfarin per day to maintain a 1.5 to 2.2 international normalized ratio. Physicians who were certain of the benefits of warfarin randomly assigned patients to fixed-dose or dose-adjusted warfarin.

Results indicated that 85 of the 1,590 study participants had a radiologically confirmed catheter-related thrombotic event. When compared with no warfarin treatment, warfarin did not reduce the rate of this outcome (6% vs. 6%; RR=0.99; 95% CI, 0.57–1.72).

However, dose-adjusted warfarin did reduce symptomatic catheter-related thromboses compared with fixed-dose warfarin (3% vs. 7%; RR=0.38; 95% CI, 0.20-0.71).

“For clinicians still wishing to offer prophylactic oral anticoagulation to patients with central venous catheters, dose-adjusted warfarin could be the most logical choice,” the researchers wrote.

Lancet.2009;373:567-574.