Washington, DC, March 25, 2026 (GLOBE NEWSWIRE) -- ATI Advisory analysis examines 2024 Medicare Shared Savings Program (MSSP) performance data to assess how episode-level spending, post-acute utilization, and readmissions shape accountable care performance. Under the newest ACO model, Long-term Enhanced ACO Design (LEAD), CMS is embedding specialty integration and episode accountability directly into the ACO model through CMS-Administered Risk Arrangements (CARA), creating a pathway to operationalize these dynamics within population-based payment.
As described in ATI’s brief, “accountable care performance is increasingly shaped by discrete clinical episodes and the 90-day post-acute care (PAC) period,” with episodes of care (shadow bundles) providing episode-level transparency into variation in specialty-driven spending and outcomes.
Data-Driven Analysis of MSSP Episodes
ATI’s analysis highlights the scale and concentration of spending on high-volume surgical and medical episodes within MSSP:
- 1.19 million inpatient and outpatient episodes occurred across MSSP ACOs in 2024
- These episodes represented $34.61 billion in estimated spending across the anchor hospitalization and 90-day post-acute period
- Episode-based spending accounted for approximately 26 percent of total MSSP ACO spending
- A subset of high-volume conditions drove a disproportionate share of ACOs’ total financial exposure
The findings underscore that episodes “are not peripheral to ACO performance,” representing more than one-quarter of total spending and concentrating financial risk within identifiable clinical conditions.
Concentration in Medical Conditions and Post-Acute Care
The analysis finds that both surgical and medical episodes contribute significantly to total spending, with high-volume conditions such as major joint replacement, sepsis, simple pneumonia, congestive heart failure, and percutaneous coronary intervention accounting for substantial episode volume and aggregate cost.
Medical episodes (e.g., sepsis, simple pneumonia, congestive heart failure, etc.) exhibit distinct risk patterns:
- Spending is often concentrated in the 90-day post-acute period following discharge
- Care pathways show greater variability compared to surgical episodes
- Readmission rates are higher than rates for surgical episodes, amplifying both cost and quality risk
Across episodes, post-acute care utilization varies significantly by condition. Certain orthopedic and fracture-related episodes show skilled nursing facility discharge rates exceeding 50 percent, while other episodes more frequently discharge patients home or to home health care. This variation reflects differences in market structure, referral patterns, and practice norms, and contributes materially to total episode cost.
Readmissions as a Driver of Financial and Quality Risk
The data brief also identifies readmissions as a key driver of episode-level performance:
- Several high-cost medical episodes have 30-day readmission rates exceeding 15 percent
- 90-day readmission rates for some conditions approach or exceed 30 percent
- Readmissions generate incremental spending within the episode window and may affect quality performance metrics
These dynamics highlight the interconnected roles of hospital care, post-acute providers, and specialists in shaping both cost and outcomes within the episode window.
Implications Under LEAD and CARA
The analysis concludes that episode-level variation is already embedded within MSSP performance and that LEAD formalizes the opportunity for ACOs to actively manage this variation.
Shadow bundles provide the underlying visibility into where financial exposure is concentrated, while CARA creates a standardized mechanism for translating that insight into aligned specialty and post-acute care accountability. As the brief notes, “the opportunity lies in identifying where episode-level variation is most material and structuring arrangements with specialists and PAC providers accordingly.”
By integrating episode accountability within the ACO structure, LEAD reinforces that specialty care performance, post-acute utilization, and readmissions are central to the total cost of care. The findings offer a data-driven foundation for ACOs to prioritize high-impact conditions, align incentives across providers, and manage performance across the full 90-day episode window.
Conclusion
The data brief demonstrates that a limited number of episodes account for a substantial share of MSSP spending, with variation in post-acute care utilization and readmission risk. Under LEAD, shadow bundles and CARA provide a framework for addressing this variation within population-based models.
As CMS continues to integrate specialty care into accountable care, the analysis highlights a clear direction: ACO performance will increasingly depend on the ability to understand and manage episode-level dynamics across specialists, hospitals, and post-acute providers.
About ATI Advisory
ATI Advisory is a healthcare research and advisory services firm dedicated to system reform that improves health outcomes and makes care better for everyone. ATI guides public and private leaders in solving the most complex problems in healthcare through objective research, deep expertise, and bringing ideas to action.
Press Inquiries
Olivia Blumenshine
olivia [at] atiadvisory.com
https://atiadvisory.com/
