The National Eye Institute 25-Item Visual Function Questionnaire (NEI VFQ-25) - reference data from the German population-based Gutenberg Health Study (GHS)

Abstract

Background: To estimate the burden of diseases, it is important to consider patient-reported outcomes including Quality of Life (QoL). The aim of this study is to provide population-based reference data for the National Eye Institute 25-Item Visual Function Questionnaire (NEI VFQ-25), stratified by sex and age. Methods: The Gutenberg Health Study (GHS) is a population-based, prospective, observational cohort study in Germany, including 15,010 participants aged between 35 and 74. The baseline examination was conducted between 2007 and 2012. To overcome known shortcomings of the NEI VFQ-25, we calculated the previously proposed visual functioning scale and the socio-emotional scale based on Rasch-transformed person-level data. We present mean values, standard deviations and percentiles for age decades stratified by sex. We used a linear regression model to assess the influence of age, sex, socioeconomic status, distance-corrected visual acuity (better-seeing eye) and the absolute difference in distance-corrected visual acuity of both eyes on vision-related QoL. Results: NEI VFQ-25 data are available from 12,231 participants (82%). Both the long-form visual functioning scale (LFVFS) and the long-form socio-emotional scale (LFSES) showed a clear age dependency, with an average LFVFS score of 92.8 for men and 90.5 for women in the youngest age group and 85.7 and 83.4 in the oldest age group, and a LFSES score of 98.3 for men and 98.1 in women in the youngest and 94.7 and 94.5 in the oldest decade. The largest difference was observed between the youngest age group (35-44years) and the 45-54years group. Men tended to have slightly higher scores than women. In the multivariable linear regression analysis, age (per 5 years -0.42), female sex (-1.57), worse distance-corrected visual acuity of the better eye (per 0.1 increase in logMAR -2.92) and the difference between both eyes (per 0.1 increase in logMAR -0.87) were associated with a reduced LFVFS score (all p<0.001). For the LFSES score, we showed that the influence of sex was minor, and that age (per 5 years -0.22), visual acuity of the better eye (-1.65), and the difference between both eyes (-0.56) were associated with a lower score (all p<0.001). Conclusions: We report age- and sex-specific reference data from a large population-based study of mainly Caucasian ethnicity of two unidimensional scores based on Rasch-transformed NEI VFQ-25 data. Vision-related QoL is lower in older and in female individuals. Our results support the association of vision-related QoL not only with the distance-corrected visual acuity of the better eye but also with the difference in visual acuity between each eye. Our findings could be used as a reference for comparison in future studies addressing the influence of eye diseases on vision-related QoL.