Like millions of older adults, Frances L. Ayres faced a choice when picking health insurance: Pay more for traditional Medicare, or opt for a plan offered by a private insurer and risk drawn-out fights over coverage.

Private insurers often require a cumbersome review process that frequently results in the denial or delay of essential treatments that are readily covered by traditional Medicare. This practice, known as prior authorization, has drawn public scrutiny, which intensified after the murder of a UnitedHealthcare executive last December.

Ms. Ayres, a 74-year-old retired accounting professor, said she wanted to avoid the hassle that has been associated with such practices under Medicare Advantage, which are private plans financed by the U.S. government. Now, she is concerned she will face those denials anyway.

The Centers for Medicare and Medicaid Services plans to begin a pilot program that would involve a similar review process for traditional Medicare, the federal insurance program for people 65 and older as well as for many younger people with disabilities. The pilot would start in six states next year, including Oklahoma, where Ms. Ayres lives.

The federal government plans to hire private companies to use artificial intelligence to determine whether patients would be covered for some procedures, like certain spine surgeries or steroid injections. Similar algorithms used by insurers have been the subject of several high-profile lawsuits, which have asserted that the technology allowed the companies to swiftly deny large batches of claims and cut patients off from care in rehabilitation facilities.

The A.I. companies selected to oversee the program would have a strong financial incentive to deny claims. Medicare plans to pay them a share of the savings generated from rejections.