This piqued my interest too. I found a few adjacent papers but couldn't find a source that made as comprehensive of a claim.
The closest were:
- "In constant battle with insurers, doctors reach for a cudgel: AI" from NYT (via Salt Lake Tribune), 2024 July, which is mostly on doctors using law-compliant LLMs to draft prior authorizations and has a passing one-graf mention of insurers likely doing the same: https://www.sltrib.com/news/nation-world/2024/07/11/constant...
"Large Language Models to Help Appeal Denied Radiotherapy Services" from JCO Clinical Cancer Information, 2024 Sept. (abstract only; full-text paywalled) https://pubmed.ncbi.nlm.nih.gov/39250740/