Factor analysis of the National Institutes of Health Stroke Scale in patients with large strokes

Arch Neurol. 2004 Nov;61(11):1677-80. doi: 10.1001/archneur.61.11.1677.


Background: The National Institutes of Health Stroke Scale (NIHSS) was created to detect treatment-related differences in clinical trials and was designed to measure right- and left-sided cerebral hemispheric function.

Objective: To validate the original design in patients with very large strokes.

Design: A previously published factor structure was fit to the data. Then, a new analysis was conducted to explore the underlying structure of the scale in this population. Finally, NIHSS scores and infarction volumes were compared.

Setting: The Clomethiazole for Acute Stroke Study-Ischemic, conducted in academic and community hospitals.

Patients: Individuals with acute stroke seen within 12 hours of onset. Of 1191 records available, 98% had complete NIHSS scores.

Main outcome measure: Goodness-of-fit statistic (Bentler) for each factor solution.

Results: Two factors were found underlying the NIHSS, corresponding to the left and right hemispheres (goodness of fit = 0.97), using the previously published factor analysis. The new exploratory analysis also suggested 2 factors representing left and right brain function. The median (range) NIHSS scores were 15 (5-25) for right brain strokes and 19 (6-32) for left brain strokes (P<.001). The median (range) infarction volumes were 56.2 mL (0.1-381.5 mL) for right brain strokes and 37.8 mL (0.2-255.1 mL) for left brain strokes (P<.001). The correlation coefficient between NIHSS score and lesion volume was 0.37 (P<.001).

Conclusions: The underlying structure of the NIHSS conforms to cerebral hemispheric lateralization, confirming previous findings in a new population of large hemispheric strokes. Left- brain strokes score 4 points higher on the NIHSS than right brain strokes of larger volume.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.
  • Validation Study

MeSH terms

  • Acute Disease
  • Cerebral Infarction / classification
  • Cerebral Infarction / pathology
  • Clinical Trials as Topic
  • Endpoint Determination
  • Factor Analysis, Statistical*
  • Functional Laterality
  • Humans
  • Severity of Illness Index*
  • Stroke / classification*
  • Stroke / pathology*
  • Stroke / therapy