Microsoft Study Finds AI Diagnostic System Beats Generalist Doctors on Complex Cases

Microsoft's AI diagnostic system correctly identified complex medical cases in a simulation more than twice as often as generalist physicians, according to a study published Thursday in Science. Mustafa Suleyman, CEO of Microsoft AI, described the result as a step toward "medical superintelligence."

The system, called MAI-DxO, coordinates multiple AI agents that function like a panel of doctors-questioning a patient, ordering tests, and debating a diagnosis. In simulations using complex cases from the New England Journal of Medicine, it was correct 83% of the time, compared with 36% for primary care doctors and general internists working individually with reference materials. The study noted that cases of this complexity are typically handled by specialists or physician teams, who were not part of the comparison.

"There is something very substantial and exciting here," Dominic King, vice president of Health at Microsoft AI, told TechCrunch. "The biggest challenge in healthcare delivery at the moment is the growing mismatch between demand and supply of medical expertise."

The study's data suggests much of the improvement stems from more powerful underlying AI models, with Microsoft's orchestration system adding gains on top. Microsoft tested MAI-DxO with models from OpenAI, Google, Anthropic, Meta, and DeepSeek, with the best results coming from OpenAI's GPT-5 and GPT-5.5.

On complex cases, DxO raised GPT-5.5's accuracy from 72% to nearly 87% at a slightly lower cost. Gains did not appear on emergency department cases, where both versions scored about 85%. DxO helped most on complex cases and with less capable models; Gemini 2.5 Flash scored 46.4% alone but nearly 69% with DxO.

Suleyman said Microsoft is working with the Mayo Clinic to train a foundation model for healthcare, planned for release next year. He predicted that by 2027 the company will be "on the verge of a coding style breakthrough for medical records."

Through a partnership with Beth Israel Deaconess Medical Center in Boston, Microsoft will evaluate DxO's clinical reasoning across hospital settings. "This technology is ready for real-world evaluations," King said, calling it likely "the biggest study of its kind."

Source: TechCrunch