Cd. Bushnell et al., Retrospective assessment of initial stroke severity - Comparison of the NIH Stroke Scale and the Canadian Neurological Scale, STROKE, 32(3), 2001, pp. 656-660
Background and Purpose-The NIH Stroke Scale (NIHSS) and the Canadian Neurol
ogical Scale (CNS) have been reported to be useful for the retrospective as
sessment of initial stroke severity. However, unlike the CNS, the NIHSS req
uires detailed neurological assessments that may not be reflected in all pa
tient records, potentially limiting its applicability. We assessed the reli
ability of the retrospective algorithms and the proportions of missing item
s for the NIHSS and CNS in stroke patients admitted to an academic medical
center (AMC) and 2 community hospitals.
Methods-Randomly selected records of patients with ischemic stroke admitted
to an AMC (n=20) and community hospitals with (CH1, n=19) and without (CH2
, n=20) acute neurological consultative services were reviewed. NIHSS and C
NS scores were assigned independently by 2 neurologists using published alg
orithms. Interrater reliability of the scores was determined with the intra
class correlation coefficient, and the numbers of missing items were tabula
ted.
Results-The intraclass correlation coefficient for NIHSS and CNS, respectiv
ely, were 0.93 (95% CI, 0.82 to 1.00) and 0.97 (95% CI, 0.90 to 1.00) for t
he AMC, 0.89 (95% CI, 0.75 to 1.00) and 0.88 (95%, 0.73 to 1.00) for the CH
1, and 0.48 (95% CI, 0.26 to 0.70) and 0.78 (95% CI, 0.60 to 0.96) for the
CH2. More NIHSS items were missing at the CH2 (62%) versus the AMC (27%) an
d the CH1 (23%, P=0.0001). In comparison, 33%, 0%, and 8% of CNS items were
missing from records from CH2, AMC, and CH1, respectively (P=0.0001).
Conclusions-The levels of interrater agreement were almost perfect for retr
ospectively assigned NIHSS and CNS scores for patients initially evaluated
by a neurologist at both an AMC and a CH. Levels of agreement for the CNS w
ere substantial at a CH2, but interrater agreement for the NIHSS was only m
oderate in this setting. The proportions of missing items are higher for th
e NIHSS than the CNS in each setting, particularly limiting its application
in the hospital without acute neurological consultative services.