The Workers Compensation Research Institute released the 17th edition of its Medical Price Index for Workers’ Compensation in May 2026, covering 36 states that represent 88% of U.S. workers’ compensation benefits paid. The study tracks physician price movements across an 18-year window from 2008 to 2025, and the central finding is structural: states without WC fee schedules charged 41% to 188% more than the typical fee-schedule state for the same professional medical services.
The price spectrum is wide. Massachusetts sat 28% below the 36-state median while Wisconsin sat 174% above it. The index covers nonhospital professional services billed by physicians, physical therapists, and chiropractors, including evaluation and management, surgery, physical medicine, radiology, pain management injections, and emergency care.
Who it affects
Any self-insured employer, captive, or public entity running a multi-state WC program. The pricing gap hits hardest for organizations with operations spanning both fee-schedule states (California, Florida, Texas) and non-fee-schedule states (Wisconsin, Indiana, New Jersey). A blended national medical severity trend masks a divergence that can exceed 100 percentage points in the physician price component alone.
The reserve mechanism: cumulative severity divergence
The MPI-WC data maps directly to the medical severity layer of the loss development triangle. Fee-schedule states held cumulative physician price growth to 19% over the 2008 to 2025 study period. Non-fee-schedule states saw 43% cumulative growth, more than double the rate.
That divergence compounds in the later development periods. Early paid data may look comparable across jurisdictions because initial treatment costs converge. The split widens as claims mature, reopenings add treatment episodes, and physician charges compound at structurally different rates. Development factors built from a blended multi-state book will systematically understate the medical tail in non-fee-schedule jurisdictions and overstate it where fee schedules cap prices.
For context, NCCI’s most recent national medical price index showed WC medical price growth at just 1.8%, a headline that averages over exactly this kind of state-level variation. The WCRI data shows that the national number is not one trend; it is at least two, separated by whether the state regulates physician reimbursement.
What this means for your next review
Ask your actuary whether the medical severity trend in your reserve analysis is calibrated at the state level or blended nationally. If blended, request a sensitivity test that applies fee-schedule and non-fee-schedule growth rates separately to your largest jurisdictions. For operations in the high end of WCRI’s spectrum (Wisconsin, Indiana, and similar non-fee-schedule states), compare your booked medical severity trend against the MPI-WC benchmark and document the gap. The report is free to download and provides the state-level data to make that comparison concrete.