Evaluation of the test-retest and inter-mode comparability of the Impact of Vision Impairment questionnaire in people with chronic eye diseases.

PURPOSE: The main objective of this study is to assess the test-retest and inter-administration mode reliability of the Impact of Vision Impairment profile (IVI), a common patient-reported outcome measure (PROM) for people with chronic eye diseases. METHODS: The IVI was administered to adult patients with stable, chronic eye diseases two to four times per participant (average intervals between administrations 12 to 20 days; maximum two phone interviews, paper administration, electronic administration) by two trained interviewers. Rasch models were fit to the data. Intra-class correlation coefficients (ICCs), mean differences and Cronbach's alpha between test-retest administrations (two phone interviews) and inter-mode comparisons were calculated. RESULTS: Two hundred-sixteen patients (mean age 67 ± 12 years, 40% male) were included in the study. The IVI met all psychometric requirements of the Rasch model, and the division into the domains of functional items (IVI_F) and emotional items (IVI_E) corresponded to the German validation study. ICCs (all for IVI_F and IVI_E, respectively) for the retest administrations were 0.938 and 0.912, and 0.853 and 0.893 for inter-mode comparisons phone/paper, 0.939 and 0.930 for phone/electronic, and 0.937 and 0.920 for paper/electronic (all p < 0.01). Mean differences (all for IVI_F and IVI_E, respectively) for the retest administrations were 2.8% and 0.7% and ranged from 2.0% to 6.2% and from 0.4 % to 4.9% between administration modes. Cronbach's alpha ranged from 0.886 to 0.944 for retest and inter-mode comparisons. CONCLUSION: Due to the high test-retest reliability and the almost equally high comparability of different modes of administration of the IVI, the study endorses its use as a robust PROM to capture vision-related quality of life. Our results further support the use of the IVI as an endpoint in clinical trials and may simplify implementing it in both clinical trials or real-world evidence generation by offering multiple administration modes with high reliability.

Patient-reported vision impairment in low luminance predicts multiple falls.

BACKGROUND: Visual impairment is an independent risk factor for falling. Whether this extends to patient-reported visual difficulties has not been assessed to date. We have evaluated whether patient-reported visual difficulties in low-contrast and low luminance situations are a risk factor for falls and concerns about falling. METHODS: Baseline assessments in outpatients with varying degrees of visual impairment aged ≥ 60 years included the Vision Impairment in Low Luminance (VILL) questionnaire and socio-demographic data; prospective follow-up assessments included falls over 12 months, the Falls Efficacy Scale (FES-I) and the VILL. The VILL was scored using Rasch models, and the FES-I was categorized following published guidelines. Associations were investigated using logistic regression analysis, controlling for age, visual acuity and known risk factors of falling. RESULTS: We included 112 participants (74 women, mean age 70 ± 7 years). Twenty-seven participants recalled any falls and eleven recalled multiple falls at follow-up. Higher VILL reading subscale and mobility subscale scores at baseline were significantly associated with reporting less multiple falls at follow-up (OR 0.559 [0.333-0.936], p = 0.027 and OR 0.595 [0.377-0.940], p = 0.026). VILL scores were significantly associated with concerns about falling (high versus low: p ≤ 0.004, reading, mobility and emotional subscales; high versus moderate: p = 0.004, emotional subscale). CONCLUSIONS: Patient-reported visual difficulties under low illumination and in low-contrast conditions are predictive of multiple falls in the future, have an additional predictive value over established risk scores, and are associated with concerns to fall. Current fall risk assessments may benefit from the inclusion of such assessments, e.g. the VILL questionnaire.

Interviewer Administration Corresponds to Self-Administration of the Vision Impairment in Low Luminance (VILL) Questionnaire.

Purpose: To quantify the impact of the mode of administration (MOA) on scores of the Vision Impairment in Low Luminance (VILL) questionnaire. Methods: The VILL questionnaire was implemented using different MOAs (paper, interview, electronic), in addition to a demographical survey of adult participants recruited at an outpatient eye clinic, with the initial MOA being either paper or interview. Polytomous Rasch models were used to generate person measure scores for the three subscales of the VILL questionnaire (reading, VILL_R; mobility, VILL_M; and emotional, VILL_E). Measures of agreement among the different MOAs were calculated (self-administered paper/interview, self-administered paper/self-administered electronic, and interview/self-administered electronic). An age-matched analysis was performed to control for the impact of the initial MOA, administration interval, visual acuity, and self-reported hearing difficulties. Results: We included 309 participants (mean age, 63 ± 14 years; 61% female). Intra-class correlation coefficients were 0.930, 0.919, and 0.799 for paper versus interview assessment; 0.951, 0.959, and 0.916 for paper versus electronic; and 0.967, 0.955, and 0.907 for interview versus electronic assessment (VILL_R, VILL_M, and VILL_E, respectively). Mean differences were 0.35, 0.41, and 1.74 logits; 0.32, 0.18, and 0.68 logits; and 0.08, 0.22, and 0.63 logits, respectively. None of the mentioned factors significantly affected the results (corrected P ≥ 0.11). Conclusions: Paper, interview, and electronic MOAs of the VILL can be considered equivalent. Reporting across the main MOAs of self-administration (paper) and interviewer-administration was unaffected by better eye visual acuity and self-reported hearing difficulties. Translational Relevance: The results support use of the VILL questionnaire with flexible modes of administration.