The evaluation of psychometric properties of headache disability inventory in the headache patients

Headache is one of the most prevalent medical complaints and causes undesirable effects on the human kind feelings and life style. Regarding these complications, the scientific society requires methods to measure them. Therefore, the purpose of this study was to obtain factor structure, validity and reliability of the Headache Disability Inventory (HDI). In an analytical-descriptive study, this inventory was administrated on 100 headache patients referred to a hospital in Shiraz. The patients selected randomly to filled in a questionnaire based on SCL-25. The validity of the inventory was investigated by three different construct validity (factor analysis), concurrent validity and convergent validity. Factor analysis of the inventory was used through varimax rotation based on Skree test. The concurrent validity of the HDI was measured by SCL-25 and in convergent validity, correlation coefficients of emotional and functional subscales with total score was calculated. The reliability coefficients of the inventory were calculated in spilt-half and internal consistency methods. Factor analysis of the inventory showed that two factors labeled emotional and functional which covered 36 percent of the total variance. In concurrent validity, correlation coefficients of the total score, emotional and functional factors of the HDI and SCL-25 were 0.71, 0.51 and 0.55, respectively. In convergent validity, correlation coefficients of emotional and functional subscales with total score were 0.79 and 0.91, and together was 0.48. In reliability, the spilt-half reliability coefficient was 0.77 and Cronbah’s alpha coefficients for total score, emotional factor and functional factor were 0.86, 0.68 and 0.83, respectively. Based on the results, this inventory (questionnaire) has appropriate reliability and validity in Iranian society and is a suitable scale for using in research and clinical situations.