Spanish cross-cultural adaptation and validation of the National Institutes of Health Stroke Scale

OBJECTIVES: To adapt and validate a Spanish-language version (SV) of the National institutes of Health Stroke Scale (NIHSS) to facilitate its use in Spanish-speaking contexts. PATIENTS AND METHODS: The methods recommended by the International Quality of Life Assessment Project were followed. Two forward translations and 1 back translation of the NIHSS were developed to ensure lingual and cultural equivalence. A final revised SV-NIHSS was administered by 8 physicians to patients with stroke in 3 clinics in Buenos Aires, Argentina, from September 2003 to December 2003. RESULTS: The study included 102 patients (mean ± SD age, 73.3±6.5 years; 56% women) with stroke (86% ischemic). The SV-NIHSS mean baseline score was 9.78±7.04. Interrater reliability was independently evaluated for 98 patients, showing a high agreement: κ, 0.77 to 0.99 for the 15 items; interrater correlation coefficient, 0.991 (95% confidence interval, 0.987-0.994). Intrarater reliability was excellent: κ, 0.86 to 1.00 for the 15 items; mean intrarater correlation coefficient, 0.994 (95% confidence interval, 0.991-0.996). Construct validity was also adequate; the SV-NIHSS had a negative correlation with baseline Glasgow Coma Scale (Spearman coefficient = -0.574, P<.001) and with Barthel Index at 3 months (Spearman coefficient = -0.658, P<.001). Patients with different Rankin scores at 3 months also had significantly different baseline SV-NIHSS scores, from a mean of 4.29±2.21 for Rankin score of 0 to a mean of 29.40±3.97 for Rankin score of 6 (P<.001). CONCLUSION: This study shows that a Spanish-language version of the NIHSS developed with internationally recommended methods is reliable and valid when applied in a Spanish-speaking setting.