Medicare Advantage plans denied prior authorization requests at unusually high rates, according to a new report from the Health and Human Services inspector general's office.

The report specifically highlighted UnitedHealthcare, CVS Health, and Humana as having the highest denial rates for long-term care requests among the plans examined.

Prior authorization is a cost-control mechanism used by insurance plans that requires patients to obtain approval before receiving certain medical services or treatments. The process is designed to ensure medical necessity and manage healthcare costs.

The findings raise questions about whether Medicare Advantage beneficiaries are receiving appropriate access to covered services. Medicare Advantage plans are private insurance alternatives to traditional Medicare that serve more than 28 million Americans.

The inspector general's office routinely examines Medicare programs to identify potential issues with access to care, billing practices, and program integrity. This report adds to ongoing scrutiny of prior authorization practices across the healthcare industry.