Genotype-guided Warfarin Dosing Vs. Conventional Dosing Strategies: a Systematic Review and Meta-analysis of Randomized Controlled Trials

Aims: Previous trials on the effectiveness of genotype-guided warfarin dosing vs. conventional dosing have been inconclusive. We conducted a systematic review and meta-analysis of randomized trials comparing genotype-guided to conventional dosing strategies.

Methods: PubMed and the Cochrane Library were searched up to 23 October 2017.

Results: A total of 76 and 94 entries were retrieved were retrieved from PubMed and the Cochrane Library, respectively. A total of 2626 subjects in the genotype-guided dosing (mean age 63.3 ± 5.8 years; 46% male) and 2604 subjects in the conventional dosing (mean age 64.7 ± 6.1 years; 46% male) groups (mean follow-up duration 64 days) from 18 trials were included. Compared with conventional dosing, genotype-guided dosing significantly shortened the time to first therapeutic international normalized ratio (INR) (mean difference 2.6 days, standard error 0.3 days; P < 0.0001; I 0%) and time to first stable INR (mean difference 5.9 days, standard error 2.0 days; P < 0.01; I 94%). Genotype-guided dosing also increased the time in therapeutic range (mean difference 3.1%, standard error 1.2%; P < 0.01; I 80%) and reduced the risks of both excessive anticoagulation, defined as INR ≥4 [risk ratio (RR) 0.87; 95% confidence interval (CI) 0.78, 0.98; P < 0.05; I : 0%), and bleeding (RR 0.82; 95% CI 0.69, 0.98; P < 0.05; I 31%). No difference in thromboembolism (RR 0.84; 95% CI 0.56, 1.26; P = 0.40; I 0%) or mortality (RR 1.16; 95% CI 0.46, 2.91; P = 0.76; I 0%) was observed between the two groups.

Conclusions: Genotype-guided warfarin dosing offers better safety with less bleeding compared with conventional dosing strategies. No significant benefit on thromboembolism or mortality was evident.