Reliability and validity of the Chinese version of the Functional Ability of the Visually Impaired ;Questionnaire by using Rasch analysis / 中国实用护理杂志

ABSTRACT

Objective To explore the psychometric properties of the Chinese version of the Functional Ability of Visually Impaired Questionnaire (CfaVIQ) by using Rasch Analysis. Methods The faVIQ was translated and adapted into the Chinese-version faVIQ (CfaVIQ). The CfaVIQ was completed by 215 visionlly impaired patients. The data were Rasch-analyzed with the Rating Scale Model of Andrich for calculating item fit statistics, determining the separation index by using Winsteps Rasch measurement program. Results Rasch model analysis indicated individual separation index (3.55) and project separation index (8.01) were both arithmetic greater than 2; the inlier-sensitive fit Mean Square (infitMnSq) and outlier-sensitive fit Mean Square (outfitMnSq) of Items, Persons were both within the range of 0.5-1.5, indicating great coincidence to the model;Wright map analysis showed the distribution of the sample ability and item difficulty was ideally normal. Coefficient of internal consistency was 3.55, separation reliability was 0.93. Pearson correlation coefficient of test-retest reliability was 0.92. Pearson correlation coefficient between CfaVIQ and vision (-0.67), visual acuity (-0.14). The National Eye Institute 25 Item Visual Function Questionnarie (NEI-VFQ25) (0.79) indicated a good construct validity. All the items′outfitMnSq, except outfitMnSq>1.5 of item 10 and item 23,were within the range of 0.5-1.5. Criterion Validity was 0.922 (95%CI0.858-0.987). Conclusions The CfaVIQ is a culturally specific vision quality of life measure instrument. It can sensitively assess the quality-of-life in the visually impaired group. Rasch measurement model can provide comprehensive and positive information and has good application prospects for analysis of CfaVIQ.