Isabel Healthcare is the oldest AI-assisted diagnostic tool in clinical use, operating continuously since 2000. Founded after a pediatric misdiagnosis involving the founder's daughter, the platform has published validation data showing a 96% diagnostic inclusion rate against published case records in a 2011 BMJ Quality & Safety study — though that study is now 14 years old.
In our 2025 testing, Isabel produced solid differential lists covering both common and rare conditions, but the interface feels dated compared to modern platforms. The workflow is less intuitive, the mobile experience is limited, and the platform is narrowly focused on differential diagnosis — there is no treatment comparison, drug dosing, or evidence synthesis.
At $750/year for individual users, Isabel is the most expensive tool on our list, which is difficult to justify given the narrower feature set. Its EHR integration via API is a strength for institutional buyers, and its track record in health systems is well established. Individual physicians should weigh the price against more modern, less expensive, or free alternatives.