Commercial Insurer Prior Authorization Rules Remain Highly Fragmented

Prior authorization (PA) criteria and approval requirements vary widely across major commercial insurers, underscoring the need for greater transparency and further scrutiny of insurer practices, according to a research letter published today in Annals of Internal Medicine.¹

Investigating the Complexity and Variability of Commercial Insurer PA Rules

The researchers noted that commercial insurer PA rules are published in provider manuals, which are often hundreds of pages long. As a result, physicians report that the complexity of PA rules, forms, and submission protocols contributes to delays in care, burnout, and adverse events.² In addition, the study of PA rules has been largely limited to Medicare Advantage plans.³

To address this gap, they conducted a study to characterize the PA rules of 3 major commercial insurers and develop a single database of PA rules.¹ Specifically, they examined publicly available provider manuals for Aetna, Humana, and UnitedHealthcare. Level 1 and 2 Healthcare Common Procedure Coding System (HCPCS) codes were grouped as medical and surgical, medication, behavioral health, or special category.

The researchers directed ChatGPT-3.5 Turbo to read each provider manual for HCPCS codes to determine whether a PA would be required, as well as the specific criteria for a PA. They also examined how insurers categorized the requirements to obtain a PA.

Based on this information, the researchers created a searchable database in Python. Additionally, they validated their results by manually comparing the number of identified HCPCS codes to the number of services listed in the corresponding provider manual.

PA Requirements Differ Dramatically Across Major Insurers

Across all HCPCS codes, no insurers shared the same criteria for requiring PA or the same requirements for obtaining one. For example, to determine the need for a PA of medical and surgical services, Aetna used only the combination of services to be provided as a criterion, and UnitedHealthcare used that along with 4 other criteria. Additionally, for approval of a PA for medical and surgical services, Aetna required only a site-of-service review, while UnitedHealthcare required that and 2 other criteria.

Overall, the 3 insurers required a PA for 4645 HCPCS codes. All 3 insurers required a PA for 638 codes (14%), 2 required a PA for 949 codes (20%), and 1 required a PA for 3058 (66%) codes. The specific criteria for needing a PA and the number of requirements to obtain one varied widely. For example, Aetna required a site-of-service review to obtain PA for more than 200 services, while Humana and UnitedHealthcare required it for only 11 and 33, respectively.

The researchers noted that the database developed for the study demonstrates that insurer PA rules can be consolidated into a single searchable database.

“PA rules change frequently, making it even more important to have a ‘living’ resource for administrators, clinicians, and patients to query,” the authors wrote.

The researchers explained that their findings are consistent with studies reporting that 4044 Part B clinical services required PA by at least 1 of 5 large Medicare Advantage insurers and that only 5.9% required PA by all insurers.² The study also adds information about the major differences in the types of services for which insurers require PA and the criteria they use.¹

They noted that these unexplained large differences “need to be scrutinized.” Although insurers recently pledged to offer electronic PA submissions and reduce the scope of PAs in response to public pressure, there is no planned standardization across insurers to eliminate fragmentation in the processes.

Findings Highlight Need for Additional Research on PA Variation

The researchers acknowledged several limitations, including that the study was limited to 3 insurers and excluded external utilization management vendors that may further complicate PA processes. Additionally, since the study was limited to processes described in the provider manuals, other PA rules and regulations may have been missed.

Still, the researchers stressed the importance of their findings, using them to suggest areas for further research.

“This study offers an example of how PA information can be collected into a single resource,” the authors concluded. “The unexplained variation that we observed requires additional research on the appropriateness of PA requirements.”

References

1. Zaari Jabri A, Asher J, Sandling J, Schulman K, Scheinker D. Variation in commercial insurer prior authorization rules. Ann Intern Med. Published online on May 18, 2026. doi:10.7326/ANNALS-25-05289
2. Health plans take action to simplify prior authorization. News release. AHIP. June 23, 2025. Accessed May 18, 2026. https://www.ahip.org/news/press-releases/health-plans-take-action-to-simplify-prior-authorization
3. Gupta R, Fein J, Newhouse JP, et al. Comparison of prior authorization across insurers: cross sectional evidence from Medicare Advantage. BMJ. 2024;384:e077797. doi:10.1136/bmj-2023-077797