Extended Hospital Stays in Medicare Advantage and Traditional Medicare.

Importance: Hospitals have reported growing difficulty in discharging patients in a timely manner, often citing bottlenecks in postacute care. Medicare Advantage plans, now the dominant form of Medicare coverage, may contribute to these delays due to administrative and network constraints, yet national evidence is lacking. Objective: To quantify changes in hospital length of stay for Medicare Advantage vs traditional Medicare beneficiaries. Design, Setting, and Participants: This retrospective cohort study used Medicare claims from 2017 through the third quarter of 2023. The sample included short-stay inpatient admissions to US acute care and critical access hospitals. Adjusted analyses were conducted on a 20% random sample, with subgroup analyses of patients discharged to skilled nursing facilities. Data were analyzed from June 2024 to June 2025. Exposure: Medicare coverage type at the time of hospital admission. Main Outcomes and Measures: Primary outcomes included length of stay (in days) and indicators for extended stays (≥7, ≥14, ≥21, and ≥28 days). Difference-in-differences regression models estimated changes in length of stay for Medicare Advantage relative to traditional Medicare, adjusting for patient demographics and hospital fixed effects. Results: The sample included 89.3 million hospital admissions. Over the study period, the mean (SD) length of stay for Medicare Advantage admissions increased from 6.0 (5.7) to 7.1 (7.6) days compared with an increase from 5.8 (SD) to 6.3 (SD) days for traditional Medicare. By the end of the study period, Medicare Advantage admissions were 1.2 percentage points (95% CI, 1.0-1.3) more likely than traditional Medicare admissions to last 14 or more days, a 19.5% increase relative to the sample mean at baseline. Relative increases were larger for stays of 21 or more days (1.2 percentage points; 95% CI, 1.0-1.3; a relative increase of 25.1%) and 28 or more days (0.28, 95% CI, 0.23-0.33; a relative increase of 31.9%). Among patients discharged to skilled nursing facilities, the adjusted probability of Medicare Advantage admissions lasting 14 or more days increased by 3.1 percentage points (95% CI, 2.6-3.6) relative to traditional Medicare, a 28.1% increase relative to the baseline sample mean. In 2022 alone, prolonged stays among Medicare Advantage patients accounted for an estimated 1.8 million additional hospital bed-days, equivalent to 288 000 additional admissions with average length of stay. Conclusions and Relevance: This cohort study found that from 2017 to 2023, Medicare Advantage beneficiaries experienced disproportionately greater increases in hospital length of stay than traditional Medicare beneficiaries, especially among those discharged to skilled nursing facilities. These trends may reflect insurance-related discharge barriers that contributed to millions of additional hospital bed-days. As Medicare Advantage enrollment continues to grow, addressing barriers to discharge may be critical for improving hospital throughput and patient outcomes.