Significance of pharmacist intervention to oral antithrombotic therapy in the pharmaceutical outpatient clinic of cardiovascular internal medicine: a retrospective cohort study

BACKGROUND: Optimised antithrombotic therapy requires clinical experience and an understanding of the current guidelines. This retrospective study aimed to evaluate whether pharmacist interviews and interventions with patients taking oral antithrombotic drugs in the pharmaceutical outpatient cardiology clinic had favourable clinical outcomes including decreased bleeding. METHODS: The participants included patients visiting the outpatient clinic of cardiovascular internal medicine at the Kobe University Hospital from January–December 2017, and were taking oral antithrombotic medication. The observation period was from the first visit to the outpatient clinic to October 2021 or death. Patients who received pharmacist intervention more than twice were defined as the pharmacist intervention group. Two control patients per one pharmacist intervention group individual were selected from the non-intervention pool matched for age, gender and antithrombotic medication type. RESULTS: Of the 895 eligible patients, 132 were in the pharmacist intervention group and 264 were selected for the matched non-intervention group. Bleeding events according to the Bleeding Academic Research Consortium criteria over type 2 were significantly lower in the pharmacist intervention group compared with the non-intervention group (17.4% versus 28.4%, P = 0.019). There were no significant differences in mortality and heart failure hospitalisation frequency, stroke, or cardiovascular events between the groups. Multivariate analysis identified age (≥ 65 years) and pharmacist intervention as factors associated with bleeding (odds ratio = 2.29 and 0.51, respectively). CONCLUSION: Pharmacist intervention in the outpatient clinic of cardiovascular internal medicine was effective in reducing the risk of bleeding in patients undergoing antithrombotic therapy.