My final PhD chapter on improving seizure detection with
@HazyResearch and
@rubinqilab was just published
@npjDigitalMed.
TL;DR We found that scaling two dimensions of model supervision: (1) coverage of training data and (2) granularity of class labels– has a large impact on model performance AND subgroup robustness for seizure detection. The best part? We do it using freely available notes produced in routine clinical workflows!
Clinical importance of building reliable seizure detection tools.
Detecting seizures, their types, duration, etc. is a critical healthcare task in diagnosing and managing epilepsy. The best way to do that is EEG analysis (reading brain recordings). But EEG analysis is a BIG pain! These recordings can be very long (hours-days per patient) and demand a scarce resource: deep neurologic-epileptologic expertise. So we have a strong need to develop reliable tools to help clinicians analyze EEG more efficiently.
Why aren’t existing models widely used?
A big reason is trust. ML models often fool us on aggregate metrics, where they show expert-level performance on average and then, whoops, they turn out to rely on non-causal features and do a lot worse for certain subgroups. We can’t have that for high-stakes healthcare settings. Another major reason is high false-alarms on abnormalities that may look like seizures, leading to alarm fatigue.
Workflow notes: a hidden goldmine for supervision.
Standard seizure detection models rely on manual labels from experts, but this approach is too expensive to scale. Luckily, routine clinical EEG monitoring leaves a trail of helpful annotations from techs, fellows, & docs. These workflow notes provide an opportunity to freely scale supervision for seizure detection models.
Scaling coverage is not enough.
Using workflow notes, we scaled our training data to include ~70k hours of EEG from ~12k patients. While this gave us impressive overall performance, we found significant performance gaps among certain patient age groups and seizure subtypes. We also found many false positives on non-epileptic abnormalities.
Scaling granularity of class labels is also needed.
Since workflow notes also include events beyond seizures (e.g., spikes, patient movement), we trained a multilabel model to predict 26 classes (including seizure). The intuition here is that increasing class granularity teaches the model to differentiate between seizures and other non-seizure abnormalities, lowering false positives. We found that our multilabel model improved overall performance, and importantly, had no significant performance gaps among subgroups.
Concluding thoughts on supervision.
It’s amazing how supervision has such a large impact on model reliability. Since supervision in healthcare is scarce, we should always keep an eye out for how we can leverage existing routine workflows to supervise our models – I am sure many more exist that we aren’t taking advantage of yet!
—
This work was done alongside amazing collaborators
@SiyiTang_, Mohamed Taha, and
@ChrisLeeMesser
It was also inspired by earlier explorations with
@jdunnmon and
@ajratner
And was supported by
@StanfordBrain and
@StanfordHAI
Check out the paper for details, including how we used SSMs for modeling, and improved on clinical utility metrics.
nature.com/articles/s41746-0…