Newsroom & Reports

Analysis Paper: How Methodological Choices Affect California’s 30-Day Hospital Readmission Rates

Key Points: 

  • The calculation of 30-day hospital-wide all-cause readmission rates varies significantly across organizations due to differences in inclusion/exclusion criteria, data sources, and operational definitions. For example, the Centers for Medicare & Medicaid Services (CMS) uses both encounter and claims data, while the California Department of Health Care Access and Information (HCAI) and the Hospital Quality Institute (HQI) rely on patient-level encounter data only.  
  • HQI’s adherence to CMS methodologies results in higher alignment with national benchmarks, whereas HCAI’s broader criteria — such as counting all readmissions within 30 days and crediting readmitting facilities — lead to inflated statewide rates and potential inconsistencies for benchmarking.  
  • HQI’s methodology, closely mirroring CMS standards, supports standardized benchmarking and state-level policy decisions, whereas HCAI’s approach, while operationally useful, lacks consistency for broader comparative analyses.  

    • Analysis Paper: Using HQI’s Hospital Similarity Clusters Improves Quality Comparisons

    Key Points:  

  • Evaluating a hospital’s performance against its peers by comparing hospital quality metrics is important, but identifying appropriate peers can be complex.  
  • Clustering hospitals based on their similarity across multiple characteristics — such as inpatient admission volume and hospital type — can help identify more comparable peers.  
  • The Hospital Quality Institute’s (HQI’s) Hospital Similarity Clusters allow for comparisons and provide insights, as demonstrated in a recent article on sepsis mortality rates. 

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