The purpose of the National Institute of Health Stroke Scale is to describe stroke severity. Every point represents a deficit on exam, so, higher is worse – except it’s not that simple.
Every point on the scale is, unfortunately, clearly unequal. Partial paralysis of the face is 2 points. Profound hemi-inattention is also 2 points. One of those patients – unless they’re Derek Zoolander – is not disabled.
This is a study, along with others in a similar vein, that translates that common sense directly into an indictment of the NIHSS as currently used. These authors retrospectively evaluate six “profiles” of patients with discrete clinical manifestations of stroke, by basing their analysis on specific NIHSS item. They use the NIHSS data from 6,843 patients in the SITS-MOST data, and, essentially, they find very different survival curves for patients with similar NIHSS when specifically categorized by clinical syndromes.
This leads to two main points:
- We shouldn’t be using the NIHSS the way we’re used to using it.
- The clinical variability of patients with similar NIHSS can vastly affect stroke trials with low sample sizes.
Time to fix the NIHSS!
“National Institutes of Health Stroke Scale Item Profiles as Predictor of Patient Outcome”