Psychometric evaluation of the near activity visual questionnaire presbyopia (NAVQ-P) and additional patient-reported outcome items.

BACKGROUND: The Near Visual Acuity Questionnaire Presbyopia (NAVQ-P) is a patient-reported outcome (PRO) measure that was developed in a phakic presbyopia population to assess near vision function impacts. The study refined and explored the psychometric properties and score interpretability of the NAVQ-P and additional PRO items assessing near vision correction independence (NVCI), near vision satisfaction (NVS), and near vision correction preference (NVCP). METHODS: This was a psychometric validation study conducted using PRO data collected as part of a Phase IIb clinical trial (CUN8R44 A2202) consisting of 235 randomized adults with presbyopia from the US, Japan, Australia, and Canada. Data collected at baseline, week 2, and months 1, 2, and 3 during the 3-month trial treatment period were included in the analyses to assess item (question) properties, NAVQ-P dimensionality and scoring, reliability, validity, and score interpretation. RESULTS: Item responses were distributed across the full response scale for most NAVQ-P and additional PRO items. Confirmatory factor analysis supported the pre-defined unidimensional structure and calculation of a NAVQ-P total score as a measure of near vision function. Item deletion informed by item response distributions, dimensionality analyses, item response theory, and previous qualitative findings, including clinical input, supported retention of 14 NAVQ-P items. The 14-item NAVQ-P total score had excellent internal consistency (α = 0.979) and high test-retest reliability (Intraclass Correlation Coefficients > = 0.898). There was good evidence of construct-related validity for all PROs supported by strong correlations with concurrent measures. Excellent results for known-groups validity and ability to detect change analyses were also demonstrated. Anchor-based and distribution-based methods supported interpretation of scores through generation of group-level and within-individual estimates of meaningful change thresholds. A meaningful within-patient change in the range of 8-15-point improvement on the NAVQ-P total score (score range 0-42) was recommended, including a more specific responder definition of 10-point improvement. CONCLUSIONS: The NAVQ-P, NVCI, and NVS are valid and reliable instruments which have the ability to detect change over time. Findings strongly support the use of these measures as outcome assessments in clinical/research studies and in clinical practice in the presbyopia population.

Qualitative exploration of the visual function impairments and impacts on vision-dependent activities of daily living in Retinitis Pigmentosa and Leber Congenital Amaurosis: content validation of the ViSIO-PRO and ViSIO-ObsRO measures.

BACKGROUND: Retinitis Pigmentosa (RP) and Leber Congenital Amaurosis (LCA) are rare inherited retinal degenerative disorders. The associated visual impairments have significant impacts on patients' vision-dependent activities of daily living (ADL), mobility, and distal health-related quality of life (HRQoL). To adequately capture patient and caregiver perspectives in clinical trials, patient and observer-reported outcome instruments must demonstrate sufficient evidence of content validity in the target population. This study aimed to explore the patient experience of RP/LCA and assess the content validity of the Visual Symptom and Impact Outcomes PRO (ViSIO-PRO) and ObsRO (ViSIO-ObsRO) instruments in RP/LCA. METHODS: A total of 66 qualitative, combined concept elicitation (CE) and cognitive debriefing (CD) interviews were conducted (33 adults, 10 adolescents, 8 children and 15 caregivers of children) in the US, France, Germany, and Canada. Patients had a clinical and genetic diagnosis of RP/LCA from a range of genotypes. CE results were used to further inform the development of a conceptual model and CD interviews assessed the relevance and understanding of the 44-item ViSIO-PRO and 26-item ViSIO-ObsRO instruments. Interviews were conducted across two iterative rounds to allow item modifications. RESULTS: Findings were consistent across RP/LCA genotypes. Night blindness, reduced peripheral vision, vision in very bright lighting and light/dark adaptation were the most frequently reported visual function symptoms impacting vision-dependent ADL and mobility. Impacts on distal HRQoL domains were also reported. The ViSIO-PRO and ObsRO items were well understood by participants and relevant across genotypes. The instructions, 7-day recall period and response scales were well understood and endorsed. Participant and expert clinician feedback supported modifications to item wording, the addition of six new ViSIO-PRO items and one new ViSIO-ObsRO item, and the removal of one ViSIO-PRO item due to lack of relevance. CONCLUSIONS: Findings support the content validity of the ViSIO-PRO and ViSIO-ObsRO instruments for use across RP/LCA genotypes. Ongoing research to evaluate the psychometric validity of the instruments will support future use of the instruments as efficacy endpoints in clinical trials and in general clinical practice to track disease severity and impact of disease on functioning.

Psychometric Validation of the ViSIO-PRO and ViSIO-ObsRO in Retinitis Pigmentosa and Leber Congenital Amaurosis.

INTRODUCTION: Retinitis Pigmentosa (RP) and Leber Congenital Amaurosis (LCA) are rare inherited retinal degenerative disorders. The Visual Symptom and Impact Outcomes patient-reported outcome (ViSIO-PRO) and observer-reported outcome (ViSIO-ObsRO) instruments were developed in this population to assess visual function symptoms and impacts on vision-dependent activities of daily living (ADL) and distal health-related quality of life (HRQoL). This study aimed to explore the psychometric properties of the ViSIO-PRO and ViSIO-ObsRO in RP/LCA. METHODS: The 49-item ViSIO-PRO and 27-item ViSIO-ObsRO instruments were completed by 83 adult and adolescent patients and 22 caregivers of child patients aged 3-11 years with RP/LCA, respectively, at baseline and 12-16-day follow-up. Concurrent measures were also administered at baseline. Psychometric analyses assessed item (question) properties, dimensionality, scoring, reliability, validity, and score interpretation. RESULTS: Item responses were mainly evenly distributed across the response scale, and inter-item correlations were mostly moderate to strong (> 0.30) at baseline within hypothesized domains. Item deletion was informed by item properties, qualitative data, and clinical input and supported retention of 35 ViSIO-PRO items and 25 ViSIO-ObsRO items. Confirmatory factor analysis in line with pre-hypothesized domains supported a four-factor model assessing visual function symptoms, mobility, vision-dependent ADL, and distal HRQoL. A bifactor model supported calculation of total scores and four domain scores. Internal consistency was high for domain and total scores (Cronbach's alpha > 0.70) and test-retest reliability for total scores was strong between baseline and 12-16-day follow-up (intraclass correlation coefficients 0.66-0.98). Convergent validity was supported by strong correlations in a logical pattern with concurrent measures. Mean baseline scores differed significantly between severity groups. Distribution-based methods provided initial insights to guide interpretation of scores. CONCLUSIONS: Findings supported item reduction and established scoring of the instruments. Evidence of reliability and validity as outcome measures in RP/LCA was also reported. Further research is ongoing to explore responsiveness of the ViSIO-PRO and ViSIO-ObsRO instruments and interpretation of change scores.

How strong should my anchor be for estimating group and individual level meaningful change? A simulation study assessing anchor correlation strength and the impact of sample size, distribution of change scores and methodology on establishing a true meaningful change threshold.

PURPOSE: Treatment benefit as assessed using clinical outcome assessments (COAs), is a key endpoint in many clinical trials at both the individual and group level. Anchor-based methods can aid interpretation of COA change scores beyond statistical significance, and help derive a meaningful change threshold (MCT). However, evidence-based guidance on the selection of appropriately related anchors is lacking. METHODS: A simulation was conducted which varied sample size, change score variability and anchor correlation strength to assess the impact of these variables on recovering the simulated MCT for interpreting individual and group-level results. To assess MCTs derived at the individual-level (i.e. responder definitions; RDs), Receiver Operating Characteristic (ROC) curves and Predictive Modelling (PM) analyses were conducted. To assess MCTs for interpreting change at the group-level, the mean change method was conducted. RESULTS: Sample sizes, change score variability and magnitude of anchor correlation affected accuracy of the estimated MCT. For individual-level RDs, ROC curves were less accurate than PM methods at recovering the true MCT. For both methods, smaller samples led to higher variability in the returned MCT, but higher variability still using ROC. Anchors with weaker correlations with COA change scores had increased variability in the estimated MCT. An anchor correlation of around 0.50-0.60 identified a true MCT cut-point under certain conditions using ROC. However, anchor correlations as low as 0.30 were appropriate when using PM under certain conditions. For interpreting group-level results, the MCT derived using the mean change method was consistently underestimated regardless of the anchor correlation. CONCLUSION: Sample size and change score variability influence the necessary anchor correlation strength when recovering individual-level RDs. Often, this needs to be higher than the commonly accepted threshold of 0.30. Stronger correlations than 0.30 are required when using the mean change method. Results can assist researchers selecting and assessing the quality of anchors.