Hospitals' growing use of artificial intelligence for coding was the biggest factor behind nearly $1 billion in additional spending by Blue Cross Blue Shield companies over two years, according to a Blue Cross Blue Shield Association report. The analysis of claims data from 2023 to 2025 found more patients were classified as medically complex as hospitals adopted AI coding tools, without evidence that the care delivered changed. Secondary diagnoses such as low sodium or anemia can move claims into higher-paying categories, increasing payments to hospitals and contributing to higher insurance premiums and out-of-pocket costs. The BCBSA network covers 1 in 3 Americans. The report comes as KFF says the median proposed premium increase for 2027 is 15%, following a 20% median increase this year. Separately, insurers face criticism over AI-assisted prior authorization, while CMS's WISeR model uses artificial intelligence to review approvals for certain Medicare procedures. Records linked to a lawsuit and previous reporting indicate the model has continued to produce delays and denials of care.