Abstract
Date Presented 4/9/2016
The National Institutes of Health Stroke Scale (NIHSS) is an acutely based measure purported to be associated with long-term outcomes and is increasingly being used in chronic trials. The study objective was to determine the concurrent validity of the NIHSS with the Stroke Impact Scale, a previously validated measure in chronic stroke.
Primary Author and Speaker: Heather Peters
Contributing Authors: Susan E. White and Stephen J. Page
PURPOSE: The purpose of this study was to determine the concurrent validity of the National Institutes of Health Stroke Scale (NIHSS) with the Stroke Impact Scale (SIS), a previously validated measure of health status in chronic stroke survivors.
RATIONALE: The NIHSS has been used historically as an acutely based measure, is purported to be associated with long-term health status, and is increasingly being used in chronic occupational therapy rehabilitative trials. Despite this increasing use of the NIHSS in research and clinical care, to our knowledge this was the first study examining associations between the NIHSS and the SIS with the purpose of determining its concurrent validity in the chronic segment of the poststroke population.
DESIGN: Secondary analysis of data collected from a multicenter, randomized controlled trial
PARTICIPANTS: One hundred forty-seven chronic (>6 mo postictus) stroke survivors with stable upper-extremity hemiparesis were included in this secondary analysis (88 men, 59 women; mean [M] age of all participants = 57.1, standard deviation [SD] = 0.9; M time since stroke onset = 59.0, SD = 5.3 mo).
METHOD: The NIHSS and the SIS were administered by blinded raters to 147 participants before participation in a multicenter randomized controlled trial. The NIHSS measures severity of symptoms associated with stroke in 11 different domains (e.g., deviation of gaze, motor arm, motor leg, aphasia). Each item is measured using a 3- or 4-point Likert scale with a score of 0 indicating no impairment and higher scores indicating more severe impairments.
The SIS is a self-report assessment of health status poststroke. It is similar to the NIHSS in that it assesses function in multiple domains (e.g., strength, hand function, activities of daily living [ADLs] and independent activities of daily living [IADLs]).
ANALYSIS: A Spearman’s ρ was used to determine correlations between NIHSS total score and (a) SIS physical dimension scores, (b) SIS overall perception of recovery scores, and (c) the SIS ADL/IADL scores. SIS score variation and medians between participants who scored a 0 versus a nonzero on the NIHSS was also assessed.
RESULTS: There was no association between total NIHSS scores and SIS physical dimension scores, SIS overall perception of recovery scores, and SIS ADL/IADL scores (ps = –.036, .782, –.039, .640, –.054, and .520, respectively). Last, significant variation and similar median scores on the SIS were found between those scoring a 0 on the NIHSS versus those who did not score a 0.
From these findings, we conclude that the NIHSS has poor validity to discern poststroke outcomes and is not associated with health status. Due to possible limitation in the NIHSS’s ability to accurately measure impairment in this population, we recommend restriction of its use to the acute stage of recovery.
IMPACT STATEMENT: The NIHSS has no association with health status in chronic stroke and lacks association with measures of impairment and functional limitation. Therefore, occupational therapists should refrain from using the NIHSS as a primary outcome measure in chronic rehabilitative trials. Furthermore, NIHSS scores should not be used to influence the content or nature of rehabilitative therapies.
