At the time of writing, there have been four randomised trials comparing different dose prediction models to standard therapy. The randomised control trial reported in Anderson et al. compared two pharmacogenetic dosing algorithms to standard warfarin therapy; the results showed that pharmacogenetic-guided dosing was superior to standard warfarin therapy according to three clinical endpoints. Pirmohamed et al. Dabrafenib cost concludes that pharmacogenetic-based dosing was associated with a higher percentage of time in the therapeutic INR range than was standard dosing during the initiation of warfarin therapy. Further, there were significantly fewer incidences of excessive anticoagulation in the genotype-guided group. However, the results from the two other randomised control trials comparing dose prediction models to standard therapy, Anderson et al. and Hillman et al., did not conclude significant differences in any outcomes. This leads to an uncertainty about the true merit of algorithms when compared with standard care. Importantly, whilst further trials comparing an algorithm guided dosing arm to standard therapy are recommeneded, the comparison is complicated by the subjective interpretation of standard therapy. With increasing numbers of RCTs being conducted for comparing these specific arms there may be the opportunity to meta-analyse the results to conclude the between study variability and, potentially, the causes of this variability. The randomised control trial, Clarification of Optimal Anitcoagulation through Genetics, had an alternative set of arms, patients dosed according to combined clinical and pharmacogenetic algorithms and patients dosed according to clinical only algorithms. The results showed that there was no significant difference between the two patient arms for multiple outcomes. The outcomes measured in COAG were time in therapeutic range, any INR readings above 4, major bleeding or thromboembolism, time to first therapeutic INR, the time to the determination of a maintenance dose and the time to an adverse event. The conclusions from this study require a different prespective on ascertaining the merit of warfarin maintenance dosing algorithms; as there were no significant differences observed between endpoints observed in the respective pharmacogenetic and non-pharmacogenetic dosing algorithm arms, a critical view of the algorithms themselves is possible. Two potential conclusions can be proposed, the extra sources of variability included in the pharmacogenetic dosing algorithm do not aid dosing in comparison to the non-pharmacogenetic algorithm or the algorithm methodology, linear regression, does not maximally implement the extra sources of variability. These two conclusions are also proposed by this manuscript, where, similarly, pharmacogenetic algorithms outcomes are relatively indistinguishable from non-pharmacogenetic algorithms. A further large, well powered trial, Genetics Informatics Trial is currently underway to investigate clinical endpoints and respective clinical ; this will provide further insight into targeted warfarin maintenance dosing. The limitations of linear regression method.