Changes in Inpatient and Skilled Nursing Facility Care After the Medicare 3-Day Rule Reinstatement.

Importance: On May 12, 2023, the Medicare program reinstated the long-standing 3-day hospitalization rule for skilled nursing facility (SNF) care after it had been waived for more than 2 years during the COVID-19 pandemic. This abrupt policy change offers a natural opportunity to assess the contemporary impact of the rule on inpatient and postacute care. Objective: To evaluate changes in inpatient length of stay, SNF utilization, spending, and short-term health outcomes among traditional Medicare beneficiaries following reinstatement of the 3-day hospitalization requirement. Design, Setting, and Participants: This retrospective cohort study of traditional Medicare beneficiaries with acute care hospitalizations included data from January and November 2023. A regression discontinuity design was used to examine changes in outcomes after the 3-day rule's reinstatement. Data were analyzed from June to November 2025. Exposures: Hospitalizations before vs on or after May 12, 2023. Main Outcomes and Measures: Primary outcomes were hospitalization for at least 3 days and SNF discharge. Secondary outcomes included 30-day rehospitalization, 30-day mortality, Medicare spending, and total SNF days. Results: This study included 332 044 unexposed hospitalizations (178 547 female patients [53.8%]; mean [SD] age, 78.3 [8.3] years) and 338 375 exposed hospitalizations (182 049 female patients [53.8%]; mean [SD] age, 78.2 [8.3] years) for traditional Medicare beneficiaries in 2023. Reinstatement of the 3-day rule was associated with a 1.13 percentage point (95% CI, 0.61-1.66; P < .001; relative change, 1.9%) increase in the likelihood of an inpatient stay lasting at least 3 days. Among patients discharged to SNFs, 3-day rule reinstatement increased the probability of an at least 3-day hospitalization by 5.57 percentage points (95% CI, 4.91-6.24; P < .001; relative change, 6.4%). No significant changes were observed in the overall probability of SNF discharge, 30-day rehospitalization, 30-day mortality, Medicare spending, or total SNF days. Subgroup analyses showed greater increases in at least 3-day stays among patients hospitalized for hip fractures and patients with dementia. Conclusions and Relevance: In this cohort study, reinstating Medicare's 3-day hospitalization requirement was associated with longer inpatient stays without decreases in SNF utilization or improvements in short-term health outcomes. These findings suggest that the policy imposes additional costs on hospitals while failing to lower Medicare spending on hospitalized patients. More generally, results raise questions regarding the value and continued relevance of a broadly applicable 3-day inpatient stay rule in the traditional Medicare program.