Evaluation of the impact of pharmaceutical care on the quality of warfarin therapy in patients without stable dose

Author(s)

Leiliane Rodrigues Marcatto

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina (FM/SBD)
• Defense date: 2021-03-31

Examining board members

Paulo Caleb Júnior de Lima Santos; Francisco Carlos da Costa Darrieux; Claudia Fegadolli

• Advisor: Paulo Caleb Júnior de Lima Santos

Abstract

Thromboembolic events are associated with high mortality and morbidity indexes. In this context, warfarin is the most widely prescribed oral anticoagulant agent to prevent and treat these events. This drug has a narrow therapeutic range and, consequently, it is difficult to achieve and maintain stable target therapeutics. Some studies in the literature showed that pharmaceutical care could improve the efficiency of anticoagulant therapy. However, there are no studies in the literature that evaluated the implementation of pharmaceutical care in patients with time out the therapeutic range (TTR<50%) in the long term. This way, the objectives of this study were to evaluate: the impact of pharmaceutical care on patients with atrial fibrillation (AF) using warfarin with low TTR (<50%); the quality of anticoagulation with warfarin in the long term after the finalization of the pharmaceutical care; and, the adherence profile to warfarin therapy on the quality of anticoagulation during the 12 weeks of pharmaceutical care. Approximately 2600 patients were evaluated and 268 patients with AF and with TTR<50%, based on the last 3 international normalized ratio (INR) values were included. These patients were followed up for 12 weeks, receiving pharmaceutical care during this period. In this caring process, the pharmacist evaluated: adherence; adverse events; instructed patients about the pharmacotherapy; evaluated drug and food interaction. In addition, INR were assessed and doses adjustments were performed when necessary. Furthermore, it was evaluated for each patient the TTR 1 year before the follow up and also the TTR 1 year after the end of the follow up with the pharmacist. The comparisons between basal TTR (which was calculated based on the three last INR values before the follow up stage) and TTR of 4 weeks (calculated by considering the INR tests from visits 0 to 4); and basal TTR and TTR of 12 weeks (calculated based on the INR tests from visits 0 to 12) revealed significant statistical differences (mean ± standard error- TTR of 12 weeks: 0.541 ± 0.015 vs TTR basal: 0.134 ± 0.010; p < 0.001; TTR of 4 weeks: 0.383 ± 0.016 vs basal TTR: 0.134 ± 0.010; p < 0.001). We also observed that the mean TTR value 1 year before pharmaceutical care was lower than TTR value after 1 year after the end of the protocol (TTR 1 year before:0.313 ± 0.015 vs TTR 1 year after: 0.565 ± 0.015; p < 0.001). Despite that, when TTR was analyzed in categories, it was noticed that 1 year before pharmaceutical care, 76% (n=199) of the patients showed TTR < 50% and 24% (n=63) of the patients had TTR50%. After 1 year of the end of the follow up with the pharmacist, 32% (n=83) of the patients showed TTR < 50, while 68% (n=179) had TTR50%. Concluding, the implementation of pharmaceutical care for patients with AF and with low TTR was able to increase TTR values and maintain the quality acquired during pharmaceutical care 1 year after the end of pharmaceutical follow up. In addition, the patients who adhered to the treatment with warfarin during pharmaceutical care, had a better quality of treatment than those who did not adhere to the therapy with warfarin. (AU)

• FAPESP's process: 16/23454-5 - Evaluation of a pharmacogenetic-based warfarin dosing algorithm in patients without stable dose
• Grantee: Leiliane Rodrigues Marcatto
• Support Opportunities: Scholarships in Brazil - Doctorate