Properties of patient-reported outcome measures in recessive Stargardt disease

Introduction: To explore the psychometric properties of the National Eye Institute Visual Function Questionnaire (NEI VFQ) and Impact of Vision Impairment profile (IVI) in recessive Stargardt disease (STGD1).
Methods: The NEI VFQ-25 and IVI-28 were administered to individuals with STGD1. Responses were analyzed following psychometrically established dimension structures of the NEI VFQ (visual function subscale, VF; socioemotional subscale, SE) and of the IVI (functional subscale, F; emotional subscale, E). We analyzed internal consistency, dimensionality, item fit and differential item functioning (DIF), using latent trait models. Criterion validity was assessed using Pearson correlation coefficients.
Results: Seventy-one participants (42 females, 29 males; mean age, 44 ±19 years) were included. Self-reported difficulty levels were lower than the mean difficulty of items in both instruments. Person reliability and person separation index of the instruments were 0.85 and 2.40 (NEI VFQ-VF), 0.69 and 1.49 (NEI-VFQ-SE), 0.88 and 2.77 (IVI-F) and 0.72 and 1.62 (IVI-E). No items showed misfit at a level distorting the measurement system. One IVI item showed DIF by gender but was retained as person measures were largely unaffected by its removal. NEI VFQ-VF and IVI-F as well as NEI VFQ-SE and IVI-E were positively correlated (r = 0.79 and 0.64, respectively).
Concl usion: The NEI VFQ and IVI have acceptable psychometric properties in STGD1 with the IVI allowing more sensitive per...

Source: Ophthalmologica - September 21, 2022 Category: Opthalmology Source Type: research