76.6% of the harmful errors in a new medical AI benchmark were omissions. Not wrong facts. Missing ones.
The study is called NOHARM (Stanford, Harvard, ARISE network). It ran 1,100 real clinical cases through tools including OpenEvidence, Doximity Ask, GPT-5.6 Sol and Claude Fable 5, with about 13,000 physician annotations of patient harm.
As an oncologist, this matches what worries me most. A hallucinated drug is easy to catch because it is wrong, and I notice it. But I don't use AI to tell me what is wrong! I use it to tell me what I am missing. My most commonly used prompt when I use AI scribe and AI clinical decision tools is "What would you do differently for this patient?" OR "What did I miss?"
It also means our usual safety check, “does this answer contain anything false?”, is aimed at the minority of the harm. This is something you can't build a benchmark for.
One more finding worth keeping: physicians using AI still delivered better care than those without it.
So how do we audit what a tool left out? I have not heard a good answer yet.