Case-mix adjustment of HCAHPS scores based on national benchmarks in Japan: a multicenter cross-sectional study
Takuya Aoki, Masato MatsushimaAbstract
Background
Despite 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.
Methods
We 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 Kendall’s τ.
Results
Data from 13,602 patients were analyzed. 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 0.77 to 1.96 points. Case-mix adjustment changed hospital rankings in 3.4–10.2% of all possible pairwise comparisons (Kendall’s τ = 0.80 to 0.93).
Conclusion
This 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 Japan’s evolving healthcare quality framework.