Health-related Quality of Life and Willingness to Pay Measurement Among Patients on Warfarin in Thailand

Background: Complex dosage regimens and the high incidence of adverse events associated with warfarin therapy can affect the health-related quality of life (HRQoL) and willingness to pay (WTP) among patients on warfarin. No such previous study has been conducted to assess the HRQoL and WTP among Thai patients on warfarin; therefore, this study aimed to measure these parameters and identify some sociodemographic factors associated with those aspects among patients on warfarin in Thailand.

Methods: This cross-sectional survey study involving 260 patients on warfarin between June 2022 and June 2023 used a quantitative method for data collection. Face-to-face interviews with well-trained interviewers were conducted and patients were required to complete the questionnaires of both World Health Organization Quality of Life-BREF (WHOQOL-BREF) and EQ-5D-5L to assess and measure their HRQoL levels. WTP was assessed using a bidding game technique. Descriptive statistics with mean and standard deviations were used to report HRQoL scores and WTP, whereas a generalized linear model was employed to identify factors associated with both HRQoL and WTP.

Results: The mean EQ-5D index and mean EQ-VAS score were 0.89 ± 0.15 and 76.92 ± 15.95, respectively, whereas the mean WHOQOL-BREF domain scores were 59.18 ± 14.13, 68.56 ± 15.47, 59.13 ± 19.64, and 65.23 ± 14.04 for the physical, psychological, social, and environmental domains, respectively. Elderly participants (age > 60 years) and those with comorbidities had lower HRQoL scores than their counterparts. The mean WTP was 22.25 ± 32.19 USD for one patient's visit. The presence of comorbidities was the only factor significantly associated with WTP values.

Conclusions: Thai patients on warfarin have lower mean EQ-5D indexes and EQ-VAS scores than members of the general Thai population. Patients on warfarin with comorbidities have diminished HRQoL and WTP values. Therefore, all healthcare professionals should pay more attention to this group of patients on warfarin to achieve better outcomes.