Using the National Institutes of Health Stroke Scale
A Cautionary Tale
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The National Institutes of Health Stroke Scale (NIHSS) is the most widely used deficit rating scale in modern neurology: over 500 000 healthcare professionals have been certified to administer it using a web-based platform. Every clinical trial in vascular neurology—prevention, acute treatment, recovery—requires a severity assessment, and the NIHSS became the gold standard for stroke severity rating after the first successful trial in acute stroke therapy, the NINDS r-tPA (National Institute of Neurological Disorders and Stroke recombinant tissue-type plasminogen activator) for Acute Stroke Trial (the Trial).1 As part of the Trial, detailed and rigorous training/certification procedures were created for the NIHSS that facilitate wider use of the scale outside of research.2
Today, payers and regulators demand reportable data on patient outcomes, and such outcomes must be adjusted for baseline severity: the NIHSS has become the de facto metric for regulatory compliance. The Joint Commission, as part of its certification program for Primary Stroke Centers, now requires an NIHSS score within 12 hours of admission for all stroke patients; this assessment is to be done by a certified examiner.3,4 Federal agencies also require outcomes adjusted for baseline stroke severity—using the NIHSS.5 Despite widening regulatory requirements, considerable problems may arise in using the NIHSS in clinical practice because the scale was designed for research purposes.6 Given that the scale was not designed for such widespread—and determinative—application, anyone using (or mandating use of) the NIHSS must understand its development history, clinimetric properties, and its proper bedside administration.
During the late 1980s, several stroke-deficit rating scales were in use.7–10 For use in a National Institutes of Health–sponsored trial of naloxone for acute stroke, investigators combined scales that had been developed at the University of Cincinnati, Canadian neurological scale, the Edinburgh-2 coma scale, and the Oxbury …