Retrospective analysis of central venous catheter-related thrombosis in 427 cancer patients prophylaxed with low-dose warfarin

Abstract

8102 Background: Cancer patients (pts) develop venous thrombosis more frequently than the general population; central venous catheters (CVC) insertion is a further risk factor. In this retrospective study, we analyzed whether low doses of warfarin are useful and safe in the thrombosis prophylaxis for cancer pts with CVC. Methods: Between July 2000 and May 2003, 427 pts (median age was 57 years; range 19–81) were evaluated. One hundred fifty-six (37%) pts had hematological malignancies. During warfarin prophylaxis, 142 pts received one (33%), 224 (52%) two, and 61 (15%) three or more chemotherapy regimens respectively. One hundred fifty-five pts (36%) underwent high-dose chemotherapy (HDT) followed by peripheral-blood-stem-cell transplantation (PBSCT). Three types of CVC were used throughout the study: 233 patients (54,5%) had an external device such as Vygon catheter, 167 (39%) had an external device such as Groshong Catheter, and 27 (6,5%) had a device completely internalized such as Port-a-cath. All pts received 1 mg/daily of oral warfarin from the day after CVC positioning until its removal. Results: The catheters were monitored for a mean of 168 days (range 22–706). There were 9 thrombotic events (1,8%). Of these, six events were observed in pts with haematological malignancies while one patient developed thrombosis during HDT. The median age was 40 years. The median number of days between line insertion and thrombosis was 152 (22–216). A number of potential predictive factors were analyzed for their impact on thrombotic events but no correlation was detected. Overall, International Normalized Ratio (INR) elevation occurred in 55 (12,8%) pts. Bleeding was observed in 15 (3,5%) pts, ten of whom had elevated INR levels. Of these, all were treated with regimens containing continuous-infusion 5-Fluorouracil (5-FU). Discussion: This large retrospective study shows that minidose warfarin can protect from clinical thrombosis. However an elevation of INR value associated to hemorrhagic symptoms can occur in pts treated with 5-FU-based regimens, suggesting a strict monitoring of these pts. No significant financial relationships to disclose.