Development and assessment of a revised Chinese version of the Catquest 9SF questionnaire for a Chinese cataract population

Objective To develop a revised Chinese version of the Catquest-9SF questionnaire and assess its applicability, item discrimination, reliability and validity in a Chinese cataract population; to provide a comprehensive and easy instrument for measuring vision function-related quality of life in China; and to analyze the influence on quality of life for patients awaiting cataract surgery. Methods This was a cross-sectional investigation. Translation, back translation and cross-cultural adaptation were used to create a revised version of the Catquest-9SF questionnaire for a Chinese cataract population. One examiner interviewed 150 cataract patients waiting for surgery at the Eye Hospital of Wenzhou Medical University. A second examiner independently interviewed 50 patients from the same group. The revised Chinese version of the 9SF was tested for its applicability, item discrimination, reliability and validity through internal consistency, inter-scorer reliability, content validity and format validity. An analysis of related factors affecting the score was also conducted. Results The revised Chinese version of the Catquest-9SF demonstrated excellent applicability and item discrimination. The questionnaire showed good internal consistency with Cronbach's α value of 0.90 and inter-scorer reliability with the Bland-Altman 95% limit of agreement value of -2.1~2.0. Pearson's correlation coefficient (0.988) also confirmed excellent inter-scorer reliability. The scale-level content validity index (S-CVI) value was 0.98. One common factor was extracted by exploratory factor analysis and explained 55.89% of the variance. The cumulative variance contribution rate also reached 55.89%. The scores showed significant correlation with visual acuity (r=0.43, P<0.01) and age (r=-0.22, P<0.01). There were statistical differences between genders (t=-2.30, P<0.05) , but there were no differences in education level, or first eye or second eye surgery. Conclusion The revised Chinese version of the Catquest-9SF is a simple and effective instrument for evaluating visual function related to quality of life in South Chinese cataract patients. The questionnaire has good applicability, item discrimination, reliability and validity. Key words: Cataract; Vision related quality of life; Chinese revised version of Catquest-9SF questionnaire; Cross-cultural adaptation