Informing Medicare's Two-Midnight Rule Policy With an Analysis of Hospital-Based Long Observation Stays.

ABSTRACT

STUDY OBJECTIVE: Outpatient observation stays are increasingly substituting for standard inpatient hospitalizations. In 2013, the Centers for Medicare & Medicaid Services adopted the controversial Two-Midnight Rule policy to curb long observation stays and better define the use of hospital-based observation services versus inpatient hospitalizations. We seek to determine the extent to which Medicare beneficiaries exposed to long observation stays (>48 hours) are clinically similar to those with short observation stays (≤48 hours) because this has relevance to the Two-Midnight Rule. METHODS: Using 100% Medicare claims data from 2008 to 2010, we identified all patients with long observation stays (>48 hours) who were admitted through the emergency department (ED). We report beneficiary characteristics, as well as crude and risk-adjusted 30-day rates of mortality, readmissions, and return ED visits stratified by observation stay length. RESULTS: Seven percent of 2.8 million observation stays were greater than 48 hours. Beneficiaries with long observation stays tended to be older, women, nonwhite, and urban residents, with a greater number of comorbid conditions. Crude rates increased with observation stay length for all 3 outcomes. However, after directly standardizing the rates, we observed the reverse trend because all adjusted rates decreased stepwise with observation stay length greater than 48 hours in a dose-response pattern. CONCLUSION: Patients with observation stays lasting longer than 48 hours are a clinically distinct population. Our findings support the conceptual underpinnings of the Two-Midnight Rule, but suggest that observation versus inpatient determinations should be based on actual length of stay rather than prospective prediction to reduce the administrative ambiguity this policy has created.