Diagnosis-Related Group - Based Case-Mix Index and Hospital Efficiency: A Systematic Review
Keywords:
Risk adjustment, inpatient financing, cost variation, resource utilization, payment reform, performance measurement, health system reformAbstract
Fair comparison of hospital efficiency requires adjustment for differences in patient complexity and resource needs. Objective: This systematic review synthesized how Diagnosis-Related Group (DRG)-based case-mix measures have been used in hospital efficiency assessment, resource allocation, and payment reform. Methods: Following PRISMA 2020 principles, PubMed, Scopus, Web of Science, and Google Scholar were searched for English-language studies published from January 2002 to December 2025. Eligible studies examined DRG or case-mix measures in inpatient hospital settings and reported efficiency, cost, resource-use, financing, or performance outcomes. Results: Ten studies met the inclusion criteria. Most used the Case-Mix Index (CMI) as a measure of clinical complexity and as a benchmark for payment or resource allocation. CMI was most consistently related to cost variation, inpatient expenditure, resource utilization, and length of stay. Fewer studies incorporated CMI directly into formal efficiency models. Conclusion: CMI is useful for risk-adjusted comparison of hospital performance, but it should not be interpreted as a standalone measure of efficiency. Strong coding systems, quality monitoring, and additional patient-level adjustment are needed for fair financing and policy use.
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