The Bureau of Labor Statistics released March 2026 CPI data on April 10, showing the hospital and related services index rose 6.4% year over year. That figure is down from 7.6% in February but still nearly double the 3.3% headline CPI. The broader medical care services index came in at 3.7%, while overall medical care CPI was 3.1%.
Two adjacent categories reinforce the pressure. Home health care services rose 7.6% year over year, and nursing home and adult day services climbed 5.2%. Physician services were more moderate, with a 0.7% month-over-month increase. For any self-insured program where medical payments drive loss costs, the hospital services sub-index is the single most important inflation input to severity trend selections.
Who it affects
Any self-insured entity with significant hospital-cost exposure in its loss runs. Workers’ compensation programs (especially those with high-severity lost-time claims involving surgery or extended inpatient care), self-funded health plans, and hospital professional liability programs all feel this directly. The impact is heaviest in states without fee schedule caps, or where fee schedules are indexed to charges rather than Medicare rates.
The reserve mechanism
The primary effect is on severity, meaning the average cost per claim. Hospital services inflation flows straight into the medical component of unpaid claim estimates. If your actuary is trending medical severity at 4% to 5% annually, the BLS data suggests that assumption may be inadequate for claim mixes with heavy hospital exposure.
Consider how this works in a Bornhuetter-Ferguson or expected-claims reserve. The actuary selects an expected loss pick for recent accident years, and that pick incorporates a severity trend factor. If the trend factor underestimates hospital cost inflation, the expected ultimate for every immature accident year will be too low, and the resulting IBNR will be understated.
The secondary effect is on case reserve adequacy. Open workers’ compensation claims with projected future medical treatment (surgeries, rehabilitation, chronic pain management) carry case reserves based on estimated future costs. If those estimates were set using a lower inflation assumption, they are already behind. When case reserves lag actual cost escalation, the reported loss triangle develops adversely, and the chain ladder picks it up as “development” rather than recognizing it as inflation-driven inadequacy. This is one of the distortions covered in the case reserve strengthening diagnostic.
NCCI’s most recent estimate of medical severity growth for workers’ compensation was approximately 6% for accident year 2024, consistent with the hospital services trajectory. That alignment matters: it means the BLS data is not an outlier but part of a sustained pattern.
What to ask your actuary
- What medical severity trend factor is embedded in our current reserve study for workers’ comp and general liability, and does it reflect the 6.4% hospital services inflation or is it anchored to the broader 3.1% medical care CPI?
- For open claims with significant projected future medical spend, are case reserves being escalated at a rate consistent with the BLS hospital services index, or are they using a lower medical inflation assumption?
- How does the 6.4% hospital services figure compare to the medical fee schedule inflation in our dominant state jurisdictions, and should we be using a state-specific trend rather than a national index?
What to watch next
The April 2026 CPI release on May 12 will show whether hospital services inflation remains above 6% for a third consecutive month. A sustained reading at that level strengthens the case for increasing medical severity trend assumptions at mid-year reserve reviews. Also watch for tariff pass-through effects on pharmaceutical and medical device pricing following the April 2 tariff announcements; if input costs rise for hospitals, the services index could re-accelerate in Q2 despite the February-to-March moderation.