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

Abstract

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 = 0.80-0.93).

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.