Linguistic and psychometric validation of the Chinese version of the Glaucoma Quality of Life-15 (GQL-15-CHI): A cross-sectional study

Abstract

Background: Maintaining glaucoma patients' quality of life (QoL) has become one of the most important goals for treatments. The purpose of this study is to develop a Chinese version of Glaucoma Quality of Life-15 item Questionnaire (GQL-15-CHI), and examine its psychometric properties.Methods: The Glaucoma Quality of Life-15 item Questionnaire (GQL-15) was translated and culturally adapted into Chinese, and administered to glaucoma patients recruited from Shanghai Eye and ENT Hospital. Visual functions: habitual-corrected visual acuity (HCVA), intraocular pressure (IOP), and mean defect (MD) of visual field) were assessed through clinical examination by professionals. Sociodemographic and other clinical data were collected via interviews and chart review. According to Nelson's glaucoma staging system, patients were stratified as mild, moderate, and severe visual field loss (VFL). The psychometric properties, including internal consistency, test-retest reliability, item-scale correlations and factor analysis were conducted. The divergent validity was assessed through bilateral comparisons of the GQL-15-CHI composite and subscale scores between patients of different VFLs after controlling for potential confounders.Results: A total of 508 glaucoma patients were recruited (male: 265, female: 243). The mean age was 55.41 years. The Cronbach's α coefficients ranged from 0.75 to 0.91 for the subscales. The test-retest reliability, as estimated by the intraclass correlation coefficients, were above 0.70 for all subscales. Statistically significant differences were showed in the GQL-15-CHI summary and subscale scores after controlling for sociodemographic and clinical confounders (P < 0.05) among patients with different VFLs.Conclusion: The GQL-15-CHI showed psychometric properties comparable to those of the original English version, and thus could be used as a reliable and valid tool for assessment of QoL in Chinese glaucoma patients. © 2013 Zhou et al.; licensee BioMed Central Ltd.