Low adjusted-dose acenocoumarol therapy in sickle cell disease: A pilot study

Vasoocclusion is a continuous process in sickle cell disease (SCD) and accu mulates to significant end organ damage, mostly irrespective of the occurre nce of manifest acute vasoocclusive events. As there are indications that r eversing the hypercoagulable state may be of clinical benefit in sickle cel l patients, we performed a randomized, double blind, placebo-controlled, cr oss-over pilot study to assess the efficacy and safety of low-adjusted dose acenocoumarol therapy (international Normalized Ratio: 1.6-2.0) in SCD. Tr eatment consisted of either acenocoumarol or placebo for 14 weeks, after wh ich treatment was discontinued for a period of five weeks. Then, patients i nitially on acenocoumarol received placebo (and vice versa) for 14 weeks. T herapy efficacy was assessed by comparing the frequency of vasoocclusive co mplications, the occurrence of bleeding, and clotting activation between ac enocoumarol and placebo treatment of each individual patient. Twenty-two pa tients (14 homozygous [HbSS] and 8 double heterozygous sickle-C [HbSC]; age d 20-59 years) completed the entire study. Acenocoumarol treatment did not result in a significant reduction of acute vasoocclusive events (three pain ful crises during acenocoumarol, five painful crises during placebo). There was a marked reduction of the hypercoagulable state (depicted by a decreas e in plasma levels of prothrombin F1.2 fragments [P = 0.002], thrombin-anti thrombin complexes [P = 0.003], and D-dimer fragments [P = 0.001]) without the occurrence of major bleeding. Even though no clinical benefit (pertaini ng to the frequency of painful crises) was detected in this pilot study, th e value of low adjusted-dose acenocoumarol for preventing specific events ( such as strokes) and as a long-term treatment of sickle cell patients shoul d be subject of further study. (C) 2001 Wiley-Liss, Inc.