Two new RP/LCA-specific instruments have reported strong evidence for psychometric validity on measures with RP/LCA adults and caregivers of children.

Researchers led by clinical scientists at the Department of Clinical Neurosciences, University of Oxford, UK, has reported that, previously, there have been no disease-specific instruments to assess the visual function symptoms and impacts of Retinitis Pigmentosa (RP)/ Leber Congenital Amaurosis (LCA). Healthcare workers, clinicians and patients have now reported to develop two new patient-reported outcome (PRO) instruments, labelled as the comprehensive Visual Symptom and Impact Outcomes patient-reported outcome (ViSIO-PRO), and observer-reported outcome (ViSIO-ObsRO) instruments,  aimed to assess the visual function symptoms and impacts on vision-dependent activities of daily living (ADL) and distal health-related quality of life HRQoL concepts in patients with RP/ LCA.

The research report, published in the journal Ophthalmol Ther (2023, 12:1359–1386), and supported by Novartis, showed that a 49-item ViSIO-PRO and a 27-item ViSIO-ObsRO instruments were completed by the cohort. The non-interventional study had recruited 83 adult and adolescent patients, and 22 caregivers of child patients aged 3–11 years with RP/LCA, respectively.  The research collected at baseline and 12–16-day follow-up data and the psychometric analyses assessed item (question) properties, dimensionality, scoring, reliability, validity and score interpretation.  Previously, the researchers commented that earlier existing PRO instruments did “not provide a comprehensive assessment of the patient experience of RLBP1 RP (and likely RP/ LCA more broadly) and contain items that lack relevance or are difficult for patients to interpret due to being insufficiently specific (i.e., items do not account for the range of lighting conditions and familiarity of environment conditions that act as moderating factors for visual function symptoms)”.  The new instruments, ViSIO-PRO and ViSIO-ObsRO, were informed by prior research and two rounds “of qualitative concept elicitation (CE) and cognitive debriefing (CD) interviews that explored the patient experience of RP/LCA and qualitatively evaluated the ViSIO-PRO and ViSIOObsRO instruments”, which provided evidence of the content validity in this RP/LCA population”.

Following the analysis of the data, the results of the ViSIO-PRO provided strong evidence for the psychometric validity and scoring of the ViSIOPRO instrument, supporting its use in broader RP/LCA and as an appropriate outcome assessment for either real-world research studies, or for clinical practice.  The findings supported 35-items in the ViSIO-PRO instrument and 25-items in the ViSIO-ObsRO instrument, characterised by the researchers as “valid and reliable measures across RP/LCA genotypes, to serve as outcome assessments in future clinical trials or track disease severity in clinical practice”. The researchers additionally commented that “further evidence is required to establish the ability of the ViSIO-PRO and ViSIO-ObsRO to detect changes over time and to inform meaningful change thresholds”.