Conflicting Readmission Rate Trends in a High-Risk Population: Implications for Performance Measurement.

The 30-day readmission rate is a common performance indicator for hospitals and accountable care entities. There is reason to question whether measuring readmissions as a function of hospital discharges is an appropriate measure of performance for initiatives that aim to improve overall cost and quality outcomes in a population. The objectives of this study were to compare trends in 30-day readmission rates per discharge to population-based measures of hospital admission and readmission frequency in a high-risk statewide Medicaid population over a 5-year period of quality improvement and care management intervention. Further, this study aimed to examine case-mix changes among hospitalized beneficiaries over time. This was a retrospective analysis of North Carolina Medicaid paid claims 2008 through 2012 for beneficiaries with multiple chronic or catastrophic conditions. Thirty-day readmission rates per discharge trended upward from 18.3% in 2008 to 18.7% in 2012. However, the rate of 30-day readmissions per 1000 beneficiaries declined from 123.3 to 110.7. Overall inpatient admissions per 1000 beneficiaries decreased from 579.4 to 518.5. The clinical complexity of hospitalized patients increased over the 5-year period. Although rates of hospital admissions and readmissions fell substantially in this high-risk population over 5 years, the 30-day readmission rate trend appeared unfavorable when measured as a percent of hospital discharges. This may be explained by more complex patients requiring hospitalization over time. The choice of metrics significantly affects the perceived effectiveness of improvement initiatives. Emphasis on readmission rates per discharge may be misguided for entities with a population health management focus.