Prevalence of financial toxicity and its association with medication adherence among patients undergoing haemodialysis under comprehensive public support in Japan

Abstract Background Beyond affordability, financial strain can induce psychological stress and a sense of financial distress, collectively termed “financial toxicity”. Although dialysis in Japan is extensively covered by public insurance, little is known about the prevalence of financial toxicity and its effects on medication adherence. This study aimed to assess the prevalence of financial toxicity and examine its association with medication adherence among patients undergoing haemodialysis in Japan. Methods This multicentre, cross-sectional study included Japanese adults undergoing in-centre haemodialysis at six facilities. Financial toxicity and self-reported medication adherence were assessed using the Comprehensive Score for Financial Toxicity (COST) and the 12-item Adherence Starts with Knowledge (ASK-12) scale, respectively. The COST scores were compared with published data from Japanese patients with cancer and patients undergoing dialysis from other countries using unpaired t-tests. Associations between the COST and ASK-12 scores were analysed using multivariate general linear models. A mediation analysis was conducted to explore potential pathways underlying this association. Results In total, 455 participants were included. The mean COST score was 22.0, and 68.5% of the participants experienced at least mild financial toxicity. Financial toxicity severity was comparable to that of Japanese patients with cancer and significantly lower than that reported among patients undergoing dialysis in Brazil and China. Lower financial toxicity (higher COST scores) was associated with fewer medication adherence difficulties (per 1-point higher: β = −.17). The mediation analysis suggested that emotional impact represents one pathway linking financial toxicity to adherence difficulties. Conclusions Despite generous public coverage, financial toxicity is common among Japanese patients undergoing haemodialysis and is associated with subjective difficulties in medication adherence.