Original Article| Volume 18, ISSUE 6, P466-468, November 2009

Interconversion of the National Institutes of Health Stroke Scale and Scandinavian Stroke Scale in Acute Stroke


      The National Institutes of Health Stroke Scale (NIHSS) and Scandinavian Stroke Scale (SSS) are both validated measures of neurologic impairment and have been used in many acute stroke trials. Methods for interconverting SSS and NIHSS are needed.


      Conversion equations were developed using linear regression (both unadjusted, and adjusted for age and sex) using a random 50% of the data at both baseline and 90 days. The remaining 50% of data were used to test the accuracy of the models produced.


      Data from 5 acute stroke trials (2004 patients) were included. Fitted models at baseline were NIHSS = 25.68 – 0.43 ∗ SSS (R2 = 0.57, prediction error [PE] –0.2, P = .20), and SSS = 50.37 – 1.63 ∗ NIHSS (R2 = 0.59, PE 0.2, P = .35). The 90-day models were NIHSS = 22.99 – 0.39 ∗ SSS (R2 = 0.82, PE –0.3, P = .001), and SSS = 56.68 – 2.20 ∗ NIHSS (R2 = 0.80, PE –0.4, P = .08). Adjustment did not materially improve the R2 values.


      Total scores for NIHSS and SSS may be interconverted with good precision; the mathematic conversion equations may prove useful in clinical practice and in comparison of data from observational studies and randomized trials.

      Key Words

      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Journal of Stroke and Cerebrovascular Diseases
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Brott T.
        • Adams H.P.
        • Olinger C.P.
        • et al.
        Measurements of acute cerebral infarction: A clinical examination scale.
        Stroke. 1989; 20: 864-870
        • Scandinavian Stroke Study Group
        Multicenter trial of hemodilution in ischemic stroke–background and study protocol.
        Stroke. 1985; 16: 885-890
        • Brown E.B.
        • Tietjen G.E.
        • Deveshwar R.K.
        • et al.
        Clinical stroke scales: An intra- and interscale evaluation.
        Neurology. 1990; 40: 352
        • Muir K.W.
        • Grosset D.G.
        • Lees K.R.
        Interconversion of stroke scales: Implications for therapeutic trials.
        Stroke. 1994; 25: 1366-1370
        • Ali K.
        • Cheek E.
        • Sills S.
        • et al.
        Development of a conversion factor to facilitate comparison of National Institutes of Health Stroke Scale scores with Scandinavian Stroke Scale scores.
        Cerebrovasc Dis. 2007; 24: 509-515
        • Ali M.
        • Bath P.
        • Curram J.
        • et al.
        The Virtual International Stroke Trials Archive (VISTA).
        Stroke. 2007; 38: 1905-1910