For many years, traditional Medicare has operated almost entirely without prior authorization, a requirement that clinicians obtain approval before certain services will be covered. The practice is controversial because it adds paperwork, outside review, and other barriers that can delay or deny coverage for recommended treatment. While widely used by commercial insurers and Medicare Advantage, traditional Medicare has historically almost never required prior authorization.
That changed in January 2026 with the launch of a new federal pilot program. Called WISeR (Wasteful and Inappropriate Service Reduction), the program is a six-year pilot that requires prior authorization for a set of services considered vulnerable to fraud, waste, and abuse in six states: Arizona, New Jersey, Ohio, Oklahoma, Texas, and Washington. The companies contracted to conduct the prior authorizations, which are mostly technology firms, are encouraged to use artificial intelligence in their prior authorization review processes. WISeR has been very controversial, but until now there has been no evidence on its effects.
A new study from the University of Minnesota School of Public Health (SPH) and Brown University School of Public Health provides the first evidence about the pilot program. Using Epic Cosmos, a large electronic health record dataset covering more than 300 million patient records nationwide, the researchers compared monthly use of WISeR-targeted services among traditional Medicare patients in the six participating states with use in all other states and the District of Columbia. The comparison covered the two years before the program's launch and the first six months after.
The study, published in JAMA, found:
- Use of services targeted by the pilot program fell. Compared with trends in states outside the pilot, epidural steroid injections for back pain-the highest-volume service in the model-declined 15%, while other targeted services declined about 20%.
- Services used as a control group showed no significant change. Services that were originally slated for WISeR but never implemented showed no decline in use, supporting the conclusion that prior authorization itself, and not some other trend, drove the decline.
- The effect was largest right after launch and weakened over time. For epidural steroid injections, the reduction fell from about 21% in the first quarter of 2026 to about 9% in the second quarter. For other services, it went from 21% to 18%. This "wearing off" effect may reflect the time it took to work out the kinks of a new workflow, the gradual learning process for clinicians to meet prior authorization requirements, or some of both.
"Traditional Medicare has operated almost entirely without prior authorization, so WISeR represents a major change in how older adults access care," said Hannah Neprash, SPH associate professor and lead author. "Our early evidence shows that these requirements had an immediate effect, with noticeable drops in use of targeted services in participating states. The key question we can't yet answer is whether the care not received was wasteful or necessary. As the Centers for Medicare and Medicaid Services considers whether to continue or expand this model, understanding its effects on patients, clinicians, and Medicare spending should be a top priority."
"As a physician, I know how burdensome prior authorization can be," said Michael Barnett, professor at Brown University School of Public Health and study co-author. "The early results suggest that doctors may be adapting rapidly to the new system. We need to watch closely to see if the additional work of prior authorization justifies what might be relatively little change in who gets care."
Study authors recommend that future work should examine whether these effects last over the model's six-year run, and how WISeR affects the appropriateness of care, patient outcomes, clinician burden, and Medicare spending.
