CMS’s FY 2027 Inpatient Prospective Payment System proposed rule (CMS-1849-P) would modify five condition-specific, 30-day, risk-standardized mortality measures: acute myocardial infarction, heart failure, pneumonia, chronic obstructive pulmonary disease, and coronary artery bypass graft surgery. Two changes matter most. The measures would add Medicare Advantage patients to the previously fee-for-service-only populations, and the performance period shortens from three years to two. In the Hospital Inpatient Quality Reporting Program, the modified measures begin with the FY 2028 payment determination; CMS proposes the same modification to the corresponding measures in the Hospital Value-Based Purchasing Program. The comment period closed June 9, 2026, with the final rule expected by August 1.
This is not a malpractice rule, and it does not change the standard of care. The reserve question is narrower and more practical: a broader, faster-moving public mortality comparison can change how a high-severity death file is selected, defended, mediated, and reserved, before it ever changes a development factor.
Who it affects
This matters most for self-insured hospitals, academic medical centers, public hospital districts, safety-net systems, and health systems that retain professional liability through a single-parent captive, group captive, trust, or large self-insured retention. Those are the organizations carrying the open death and catastrophic-deterioration files in the five affected service lines on their own balance sheets. The added Medicare Advantage population is the swing factor: MA now covers more than half of all Medicare beneficiaries, so folding those patients into measures that were historically fee-for-service-only materially enlarges the denominator behind each hospital’s public mortality rate, and can move a hospital’s percentile against peers without any change in clinical practice.
The reserve mechanism: a severity signal, not a frequency driver
For hospital professional liability IBNR, the dominant lever is severity, not claim frequency. Public mortality scoring does not create adverse events. What it does is change the information environment around the worst files, and HPL is a line where the worst files are where the money is.
Size the severity backdrop these signals feed into. Milliman’s 2025 medical professional liability update puts the severity trend at 5.0% on an unlimited basis and 4.5% limited to $5 million per claim, a 0.5-point increase over its 2023 review, drawn from roughly 40,000 closed claims and a database exceeding $26 billion in incurred losses. The share of closed claims with $1 million-plus indemnity has climbed steadily since 2013, and the $5 million-plus band has grown faster still. S&P Global Market Intelligence reports that median awards for major cases more than doubled in 2025, that payments of $500,000 or more reached 36.5% of total medical malpractice payments in 2024 (in 2025 dollars, a record), and that the line ran a combined ratio above 105% in 2025 for the fifth time in eight years. Third-party litigation funding, which grew 44% in the U.S. between 2019 and 2022 per Milliman, is lengthening litigation and raising settlement targets. This is the same severity engine documented in seven straight years of double-digit med-mal premium increases across multiple states.
Against that backdrop, the practical risk is late case reserve strengthening. If a hospital carries open death cases at routine values until an expert report ties one to a service-line outlier, the reported triangle recognizes severity late. That pushes the latest diagonal worse and nudges the actuary toward higher reported development factors or a higher selected expected claim ratio. Shortening the lookback to two years and broadening the population to include MA patients make the public metric move faster and earlier, which is precisely what raises the odds that a quality outlier surfaces before, not after, the claim file is set at full value. The measure becomes a leading governance signal; it does not become a substitute for claim-level analysis.
Where this shows up in your reserves
Start with the large-loss inventory and open-claim listing, not the aggregate triangle. The diagnostic is the count and case reserve amount for open professional liability files involving death or catastrophic deterioration in the five affected service lines, split by accident year, facility, allegation type, and attorney representation. Then lay that against the quality dashboard that feeds Care Compare and Hospital Value-Based Purchasing. Where the same service line shows adverse mortality movement and rising open severe case reserves, that pairing belongs in the reserve diagnostic review rather than being discovered a year later in emergence.
The scale of the measured population is why this is worth the effort. The Aon/ASHRM 2024-2025 benchmark analyzes 117,700 non-zero claims from 2015 through 2024, representing $32.9 billion in incurred losses across 113 health systems that together hold about 37% of U.S. hospital exposures. Aon develops countrywide HPL severity and loss rates to $5 million per occurrence, with excess layers in $5 million increments up to $25 million; for a self-insured system, the difference between catching a service-line pattern at the case-reserve stage and catching it in the excess layer is the difference between a managed reserve and a surprise.
The Hospital-Acquired Condition Reduction Program is unchanged in the proposal; CMS continues to cut overall Medicare fee-for-service payments by 1% for hospitals in the worst-performing quartile. The proposed rule also adds a 30-day sepsis readmission measure to the Hospital Readmissions Reduction Program for the FY 2029 program year, a parallel signal worth tracking alongside the mortality changes. Staffing pressure runs underneath both; the Joint Commission’s NPSG.12 staffing-effectiveness expectations bear on the same deterioration-and-rescue failures that turn a death case into a severity claim.
What this means for your next review
The directional read is that public mortality data is becoming a more usable early-warning input for HPL case adequacy, and self-insureds and captives that wire it into claim triage will recognize severity earlier and with less whipsaw than those who treat CMS scoring as a payment-department concern. Do not trend HPL losses off CMS star ratings; the correlation is not tight enough to drive a loss pick, and a tort-reform shift like Virginia’s SB 536 adverse-event disclosure law can move claim behavior independently of any quality metric. The right use is narrower and defensible: put the five modified measures on the agenda for the next reserve study or interim monitoring meeting, and require claims, quality, and finance to reconcile severe open files against service-line mortality outliers before the actuary locks case-adequacy assumptions, large-loss treatment, or the expected claim ratio. Watch the August final rule for whether the MA addition and the two-year period survive intact, because both determine how fast the signal moves. The goal is not a new loss-trend input. It is making sure your worst open files are being read with the same clinical context your organization already applies to its quality reporting, while the severity environment is the most expensive it has been on record.
Sources
- CMS FY 2027 IPPS Proposed Rule Home Page
- CMS FY 2027 IPPS proposed rule fact sheet (CMS-1849-P)
- Federal Register, FY 2027 IPPS proposed rule
- Hall Render: CMS Publishes FY 2027 IPPS Proposed Rule
- Coronis Health: 2027 IPPS Proposed Rule Quality Programs
- Milliman: 2025 Medical Professional Liability Update
- Insurance Journal / S&P Global Market Intelligence: Claim Severity Trends for Medical Malpractice ‘Stand Out’
- Aon/ASHRM Hospital and Physician Professional Liability Benchmark Report
- CMS Hospital-Acquired Condition Reduction Program