http://stroke.ahajournals.org/content/46/2/395.abstract?etoc
External Validation on Independent Trial Data
- Azmil H. Abdul-Rahim, MRCP, MBChB;
- Rachael L. Fulton, PhD;
- Heidi Sucharew, PhD;
- Dawn Kleindorfer, MD;
- Pooja Khatri, MD;
- Joseph P. Broderick, MD;
- Kennedy R. Lees, MD;
- for the VISTA Collaborators
+ Author Affiliations
- Correspondence to Azmil H. Abdul-Rahim, MRCP, MBChB, Institute of Cardiovascular and Medical Sciences, University of Glasgow, 44 Church St, G11 6NT Glasgow, United Kingdom. E-mail Azmil.Abdul-Rahim@glasgow.ac.uk
Abstract
Background and Purpose—National Institutes of Health Stroke Scale (NIHSS) item profiles that were recently proposed may prove useful both clinically
and for research studies. We aimed to validate the NIHSS item profiles in an acute cohort.
Methods—We conducted a retrospective analysis on pooled data from randomized clinical trials. We applied the latent class analysis
probabilities of profile membership developed from the derivation study to obtain symptom grouping, a-NIHSS item profiles. We implemented an independent latent class analysis to derive secondary symptom grouping, b-NIHSS
item profiles. Validation was performed by assessing the associations
with outcomes and evaluating both sets of NIHSS
item profiles’ discrimination and calibration
to the data. The outcomes evaluated included modified Rankin Scale
(mRS; using
the full distribution and dichotomized, mRS,
0–1) at day 90 and mortality by 90 days.
Results—We
identified 10 271 patients. Ordinal analysis of mRS confirmed increased
odds of better outcome across the profiles in a
stepwise manner, adjusted for age and
thrombolysis treatment, for each set of NIHSS item profiles. Similar
patterns were observed
for mRS 0 to 1, and inverse patterns were
seen for mortality. The c-statistics of a-NIHSS and b-NIHSS
item profiles for mRS 0 to 1 were similar at 0.71 (95% confidence
interval, 0.70–0.72) and for mortality, 0.74 (0.73–0.75)
and 0.75 (0.73–0.76), respectively.
Calibration was good.
Conclusions—These
NIHSS item profiles identified using latent class analysis offer a
reliable approach to capture the true response patterns
that are associated with functional and
outcome and mortality post stroke. This approach has the potential to
enhance the
clinical value of the overall NIHSS score.
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