Establishment of the Thai version of National Institute of Health Stroke Scale (NIHSS) and a validation study.

BACKGROUND The National Institute of Health Stroke Scale (NIHSS) is a well validated stroke severity assessment scale. The scale is used to assess neurological deficits, progression and degree of recovery in acute stroke settings. To date, no Thai version exists. OBJECTIVE This study aimed to adapt and validate a Thai version of the NIHSS (NIHSS-T). MATERIAL AND METHOD A cross-cultural adaptation of the NIHSS was developed according to the methods recommended by the International Quality of Life Assessment Project Group. Forward and backward translations were performed. A final version of the NIHSS-T was validated against initial MRI infarction volume and modified Rankin Scale (mRS) at 3 months in a consecutive series of acute stroke patients. The patients were prospectively evaluated by 3 different types of health care providers: 2 stroke fellows, 2 internists, and 2 stroke nurses. Mean NIHSS-T scores from all raters were used in the analysis. RESULTS The study included 32 acute ischemic stroke patients with a mean age (+/- SD) of 64.53 +/- 14.97 years of age. Men comprised 71.9%. Mean NIHSS-T score (+/- SD) was 7.49 +/- 7.02. Intra-observer reliability demonstrated a high agreement with an intraclass correlation (ICC) of 0.98, 0.98, 0.96, 0.98, 0.90 and 0.98 for 2 stroke fellows, 2 internists and 2 stroke nurses respectively. Inter-observer reliability between 6 raters was excellent, i.e.; ICC, 0.99 (0.98, 0.99). Spearman rank correlation coefficients between the initial NIHSS-T score versus initial MRI lesion volume and mRS at 3 months were 0.53 and 0.69 with a p-value of 0.002 and < 0.001 respectively. CONCLUSION The Thai version of NIHSS is valid for assessing acute stroke severity. The scale is also reliable when administered in a Thai-speaking setting by trained healthcare professionals.