What the research found
Researchers gave 200 de-identified outpatient and emergency department notes to 20 general-purpose AI models and priced each model's care plan against the plan the treating physician actually made, using 2026 Medicare rates. AI plans averaged $314 per visit versus $97 for physicians, with diagnostic testing and specialist referrals making up most of the $216 difference; where physicians ordered no tests, the models added testing in 45% to 79% of cases. Cost-conscious prompting lowered costs but, for most systems, also lowered agreement with physicians' diagnoses.
An AI that orders more is not automatically safer, and every extra test or referral it suggests reaches patients as cost, waiting and follow-on procedures unless a clinician pushes back.