Impact of genotype-guided dosing on anticoagulation visits for adults starting warfarin: a randomized controlled trial.

AIM: This study aimed to assess the effectiveness of genotype-guided warfarin dosing. PATIENTS & METHODS: A total of 109 adults were randomized to receive initial dosing as determined by an algorithm containing genetic (VKORC1 and CYP2C9) plus clinical information or only clinical information. Primary end points were the number of anticoagulation visits and the time in therapeutic range (TTR) over 90 days. Secondary end points included time to therapeutic dose, International Normalized Ratios of >4, emergency visits, hospitalizations, hemorrhagic events, thrombotic events and mortality. RESULTS: Neither primary end point was significantly different between groups (anticoagulation visits: 6.96 vs 6.37, p = 0.51; TTR: 0.40 vs 0.43, p = 0.59). Fewer emergency visits, hospitalizations, major hemorrhagic events, thrombotic events and deaths occurred in the genetic plus clinical group than in the clinical only group, but these differences were not statistically significant. CONCLUSION: Genotype-guided dosing did not decrease the number of anticoagulation visits or improve TTR. Our trial was not powered to detect anything but large differences for utilization and health outcomes.