An Age- and Stage-Appropriate Patient-Reported Outcome Measure of Vision-Related Quality of Life of Children and Young People with Visual Impairment

Abstract

Developmentally sensitive measures of vision-related quality of life (VQoL) are needed to capture age-specific concerns about the impact of living with visual impairment (VI) in children and young people. Our objective was to use our validated VQoL instrument for children and young people 10 to 15 years of age (the VQoL_CYP) as the foundation for development of age-specific extensions. Questionnaire development. A representative sample of children and young people 6 to 19 years of age with VI, defined as visual acuity worse than 0.50 logarithm of the minimum angle of resolution in the better eye. They were recruited from pediatric ophthalmology clinics at Great Ormond Street Hospital and Moorfields Eye Hospital and, in the final phase of the study, from 20 additional United Kingdom hospitals. Standard instrument development processes were followed across 4 phases. Twenty-nine semistructured interviews with children and young people permitted draft age-appropriate extensions. Twenty-eight cognitive interviews informed items and response options. Age-appropriate extensions were prepiloted with 49 participants to ensure feasibility and administered via a postal survey to a national sample of 160 participants for psychometric evaluation using Rasch analysis. Construct validity was evaluated through correlations with the Pediatric Quality of Life Inventory. Psychometric indices of validity and reliability of the instrument versions. Interviews confirmed that the existing VQoL_CYP content and format were relevant across a wider age range. Age-appropriate extensions were drafted for children (8-12 years) and young people (13-17 years). Psychometric item reduction produced 20-item child and 22-item young person versions, each with acceptable fit values, no notable differential item functioning, good measurement precision, ordered response categories and acceptable targeting, and no notable differential item functioning on items common to both. Construct validity was demonstrated through correlations with health-related quality of life (r= 0.698). Using an efficient child- and young person-centered approach, we developed 2 robust, age-appropriate versions of an instrument capturing VQoL that can be used cross-sectionally or sequentially across the age range of 8 to 17 years in research and clinical practice. This approach may be applicable in other rare childhood ophthalmic disorders.