Effectiveness of pharmacist-participated warfarin therapy management: a systematic review and meta-analysis

Although pharmacist-participated warfarin therapy management (PWTM) has been accepted and implemented in various parts of the world, the evidence demonstrating the effects of PWTM compared with usual care on clinical outcomes is lacking. We performed a systematic review and meta-analysis to compare the effects of PWTM with usual care on bleeding and thromboembolic outcomes.

We searched MEDLINE, SCOPUS, EMBASE, IPA, CINAHL, Cochrane CENTRAL, Thai Index Medicus and Thai Medical Index, and reference lists of studies, without language restriction. Databases were searched from their inception to July 2009. The studies using warfarin as an anticoagulant with sufficient data for compilation of 2 × 2 tables were included. Both randomized controlled trials (RCTs) and non-RCTs were considered. Two authors independently reviewed each study, assigned quality scores and extracted data for all outcomes using a standardized form. Pooled effect estimates (risk ratio; RR) were obtained using a random effects model.

Of 661 articles identified, 24 studies with 728,377 patients were included. In the random-effects meta-analysis of RCTs, the PWTM group had statistically significant effects on the prevention of total bleeding [RR, 0.51; 95% confidence interval (CI), 0.28-0.94]. However, the effects on major bleeding (RR, 0.64; 95% CI, 0.18-2.36), thromboembolic events (RR, 0.79; 95% CI, 0.33-1.93), all-cause mortality (RR, 0.93; 95% CI, 0.41-2.13) and warfarin-related mortality (RR, 0.65; 95% CI, 0.18-2.42) were not significant.

Pharmacist's participation in the management of warfarin therapy significantly reduces total bleeding, with a non-significant trend towards decreases in other warfarin-related complications.