Home medicines reviews in Australian war veterans taking warfarin do not influence international normalised ratio control

Background: The clinical outcomes of warfarin are largely dependent on the International Normalised Ratio (INR) control achieved, and strategies to improve the time in therapeutic range (TTR) should be identified and widely implemented in practice.

Aims: We aimed to investigate the influence of pharmacist-led medication reviews on INR control and observe the quality of INR control in Australian veterans who take warfarin.

Methods: We undertook a retrospective cohort study using administrative claims data for Australian veterans and war-widows identified by the Department of Veterans' Affairs who were regularly dispensed warfarin and invited them to contact the research team. Pathology providers were subsequently contacted to provide INR results.

Results: INR data were available for 344 of 818 (42.1%) veterans who consented to participate in the study; 64.4% were male and the median age was 83 years. The overall TTR for the veteran cohort during the study period was 64.0%. There was no difference in the TTR in the 6 months following home medicines review (HMR) compared with the control group (63.0% vs 67.0%, P = 0.27), with the TTR in patients with INR data available in the 6 months prior to, and the 6 months following HMR, remaining high (67.9% vs 69.6% P = 0.63). Approximately, one-third of veterans in this study had a percentage TTR below 60%.

Conclusions: INR was well-controlled in this elderly cohort, comparable to that achieved in recent randomised trials involving warfarin. Pharmacist-led medication reviews were not associated with a change in INR control.