The validation of the disease-specific questionnaire for health-related quality of life in Thai patients with hemifacial spasm.

OBJECTIVE To investigate the reliability and validity of the Thai version of disease-specific health-related quality of life instrument for patients with hemifacial spasm (HFS) as well as their response to botulinum toxin treatment. MATERIAL AND METHOD A Thai version of HFS-30 has been developed with the permission of the author. Thirty patients with HFS were asked to complete this Thai HFS-30, the 6-point disability scale before treatment and between four and six weeks after botulinum toxin injections. Peak improvement (0-100%) was subjectively assessed by each patient between four and six weeks after injection. They were also asked to answer the existing Thai SF-36 questionnaire before treatment to test its correlation with Thai HFS-30. Another group of ten patients completed the questionnaire and then a second identical copy after a 2-week interval. The reliability, validity, and responsiveness were subsequently analyzed. RESULTS The Thai HFS-30 showed a Cronbach's alpha coefficient of 0.78 and no significant difference of a test-retest reliability. The total content validity was 0.88 (range 0.5-1.0). There were good correlations between both the Physical and Mental Health parts of the Thai HFS-30 and Thai SF-36 (p < 0.05 and p < 0.01, respectively). The Thai HFS-30 also demonstrated a response to treatment similar to the 6-point disability scale and the peak improvement. CONCLUSION The Thai version of HFS-30 is a valid, reliable, and sensitive to change instrument for disease specific health-related quality of life assessment.