Effects of Warfarin-Related Major Bleeding Adverse Events to Hospitalization and Direct Costs in Elderly Patients in Thailand

Abstract

Background: Warfarin remains the first-line therapy for thromboembolism prevention in Thai patients with atrial fibrillation but carries major bleeding risks, particularly among elderly patients who experience age-related pharmacokinetic changes, declining hepatic and renal function, and polypharmacy. These factors increase warfarin levels, leading to supratherapeutic INR, hospitalization, and higher healthcare costs. At Buddhachinaraj Phitsanulok Hospital, one-third of warfarin-treated patients are aged ≥75 years; however, no data currently exist regarding the incidence and outcomes of adverse events in this population.

Objective: To compare the risk of major bleeding between atrial fibrillation patients aged 65–74 years and those aged ≥75 years.

Methods: This retrospective cohort study included atrial fibrillation patients receiving warfarin at Buddhachinaraj Phitsanulok Hospital between January 1, 2019, and January 31, 2022. Data on major bleeding incidence, hospital length of stay, and direct medical costs were obtained from hospital databases and the Warfarin Registry Network.

Results: Among 645 patients (mean age 75.75 ± 7.24 years; mean CHA₂DS₂-VASc score 3.54 ± 1.10), major bleeding occurred in 8.35% (28 patients) of the ≥75-year group and 6.12% (19 patients) of the 65–74-year group. The median length of stay was 5.5 versus 4.0 days (p-value = 0.20). Median direct medical costs were significantly higher in the ≥75-year group (THB 33,530.50) compared with the 65–74-year group (THB 22,280.00; p-value = 0.04).

Conclusions: Among warfarin-treated patients with atrial fibrillation, those aged ≥75 years had a higher, though not statistically significant, incidence of major bleeding and significantly greater direct medical costs than those aged 65–74 years.