Case-mix adjustment of HCAHPS scores based on national benchmarks in Japan: a multicenter cross-sectional study

ObjectivesDespite the increasing adoption of patient experience measurement in Asia, including Japan, limited progress has been made in identifying suitable patient-level adjusters and developing statistical methods for case-mix adjustment. This study aimed to develop and evaluate a case-mix adjustment model for the Japanese version of the Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) using nationwide benchmark survey data. MethodsWe conducted a multicenter cross-sectional study using data from 83 hospitals across Japan that participated in the 2023 national patient experience survey. Self-administered questionnaires were distributed to adult inpatients (aged [≥]20 years) discharged between September and November 2023. The Japanese version of HCAHPS, comprising six composite measures and two global ratings, was used to calculate top-box scores (percentage of most positive responses). Candidate case-mix adjusters included age, gender, self-rated general health, self-rated mental health, and admission through the emergency department. The explanatory power (EP) of each adjuster was calculated as the product of predictive power and the between-versus within-hospital variance ratio. The impact of adjustment was evaluated by comparing unadjusted and adjusted scores and by assessing hospital rank changes using Kendalls {tau}. ResultsOf 31,028 distributed questionnaires, 13,602 were returned (response rate 43.8%). Self-rated mental and general health showed the highest EP, whereas gender and emergency admission contributed minimally. The mean absolute adjustment of top-box scores ranged from 1.52 to 3.20 points. Case-mix adjustment changed hospital rankings in 7.4-16.5% of all possible pairwise comparisons (Kendalls {tau} = 0.67-0.85). ConclusionsThis study provides the first evidence-based case-mix adjustment model for HCAHPS scores in Japan. Applying such an adjustment is crucial to ensure fair benchmarking of PX across hospitals and to support data-driven quality improvement and accountability initiatives within Japans evolving healthcare quality framework.