Improving warfarin therapy through implementation of a hospital-based pharmacist managed clinic in Jamaica

Abstract

Background: Pharmacist managed warfarin clinics can improve the anticoagulation status of non-valvular patients. The first of such services was implemented at the Cornwall Regional Hospital in Jamaica in 2013.

Objectives: To assess the anticoagulation control of patients on warfarin therapy over six months in the pharmacist managed warfarin clinic at Cornwall Regional Hospital.

Methods: Retrospective docket review for the period January 2014 to December 2016 was done to include data of patients attending routine clinic appointments for at least six months. Age, gender, date of visit, indication for warfarin therapy, warfarin dose and International Normalized Ratio readings were extracted. Percentage time spent in therapeutic range (TTR) was calculated by month for six months using the Rosendaal linear interpolation method. Patient anticoagulation status was categorized as poor (TTR<40%), moderate (TTR=40-64%) or good (TTR≥65%) and anticoagulation status at three months and six months was compared.

Results: For the period of assessment, 52 patients were identified; the median age was 58 years and 36 patients were males. Deep vein thrombosis was the main indication for therapy (22 of 52) and median warfarin weekly dose ranged was 15.0-130 mg. At time of recruitment most of the patients were outside the target INR range (43 of 52). Within one month, the median TTR attained was 31% [IQR 62-10]. This significantly improved by second month to 60% [IQR 82-23] (p=0.001). By month three, the proportion of patients in good, moderate and poor anticoagulant status was 19/51, 15/51 and 17/51 respectively, which at six months changed to 23/51, 12/51. 16/51 respectively; thus, although coagulation status improved from month one to three, there was no significant improvement from month three to month six (p=0.31).

Conclusions: The pharmacist managed warfarin clinic monitoring services were successful in attaining TTRs >40% and sustaining these values over six months. The services should therefore be encouraged.

Keywords: Anticoagulants; International Normalized Ratio; Jamaica; Pharmaceutical Services; Pharmacists; Program Evaluation; Retrospective Studies; Warfarin.

Figure 1. Change in anticoagulation status of patients on warfarin therapy from month three to month six; bars represent anticoagulation status at month six.

At month three the proportions of patients in good, moderate and poor anticoagulation status were 19, 15, 17 respectively. By six months the proportions changed to 23, 12 and 16 respectively. With some patients improving and some deteriorating, the overall anticoagulation status remained the same from month three to month six (McNemar-Bowker pairwise chi-square=3.60; degrees of freedom=3; p=0.31).