Feasibility of the Radner reading chards in low vision patients

Background: Being unable to read is a major problem for visually impaired patients. Since distance visual acuity (VA) does not adequately reflect reading ability, it is important to also evaluate near VA. The Radner Reading Charts (RRCs) are available to measure patients' reading performance. The present study tested the inter-chart and test-retest reliability of the RRCs in Dutch low-vision patients (i.e., visual acuity ≥0.3 logMAR) with various eye disorders. Methods: Thirty-eight patients read the three RRCs in random order. Then, about 1 month after the initial measurements, a test-retest procedure was performed in 15 of the 38 patients. Tested variables were reading acuity (logRAD), logRAD score, logRAD/logMAR ratio, maximum reading speed (MRS), and critical print size (CPS). Both MRS and CPS were calculated in two different ways. To determine the variability, a mixed-model analysis was used. Results: For all variables, the largest part of the variance was explained by the individual subject (86-89%) whereas the chart accounted for only 0-0.78% of the variability. Therefore, the inter-chart and test-retest reliability was high, except for the CPS which had a poor to moderate reliability (31-62%) when calculated in the two different ways. Conclusions: The inter-chart and test-retest results showed high reliability in patients with low vision due to various diseases; therefore, the charts are feasible to determine effects in large groups. © 2010 Springer-Verlag

Applying multilevel item response theory to vision-related quality of life in Dutch visually impaired elderly

PURPOSE: Instead of applying the usual longitudinal methods to assess the outcome of low-vision rehabilitation services in terms of vision-related quality of life, a three-level Item Response Theory (IRT) method was proposed. METHODS: The translated Vision-Related Quality of Life Core Measure (VCM1) and Low Vision Quality Of Life (LVQOL) questionnaires were used in a nonrandomized follow-up study among elderly patients (n = 296) referred to two different low-vision rehabilitation services in the Netherlands. Factor analysis was performed on the matrix of polychoric correlations to investigate (uni-)dimensionality and to prepare both questionnaires for the multilevel IRT analyses. A statistical model, which was characterized by a graded response model for rating scales, was developed. Threshold and item difficulty parameters and group by time-specific mean fixed effects were estimated. Random individual effects were predicted. Measurement invariance across occasions was tested. RESULTS: The VCM1 and the LVQOL "reading and fine work" dimension showed item parameter drift. In the multidisciplinary rehabilitation center patients, deterioration was found on the "mobility" dimension after 1 year and improvement was found on "adjustment" and "visual (motor) skills" after 5 months (p < 0.05). Patients in both low-vision services showed improvement on the "reading small print" subscale at both follow-up time points (p < 0.05). CONCLUSIONS: Except for improvement in "reading small print," low-vision rehabilitation services did not seem to contribute substantially to any other dimensions of vision-related quality of life. The results showed a change in only a limited number of individual patients. However, with regard to the field of low-vision rehabilitation, the proposed IRT method seemed to be successful in the follow-up of individuals. IRT specific software was unnecessary. The data did not have to be complete and the use of cumulative logits made the proposed IRT method an economical and efficient approach. Because of item parameter drift, the VCM1 was difficult to interpret. The use of multilevel IRT models with longitudinal data and dependent observations is recommended

Visual Functioning Questionnaire: reevaluation of psychometric properties for a group of working-age adults

PURPOSE: The Visual Functioning Questionnaire (VFQ-25) is one of the most widely used measures of vision-related quality of life. However, the questionnaire does not meet some psychometric quality criteria. The objectives of this study were first to obtain the factor structure of the VFQ-25, and second, to obtain interval scales by Rasch analysis. METHODS: The questionnaire was administered to 129 visually impaired adults (mean age 42.1 years; range 21 to 67 years). First, the items of the VFQ-25 were subjected to an exploratory factor analysis with Promax rotation. Next, we performed a separate Rasch analysis on each factor. We examined step thresholds and goodness of fit statistics of the items. Finally, we examined differential item functioning. RESULTS: Factor analysis indicated four factors: Near Activities, Distance Activities and Mobility, Mental Health and Dependency, and Pain and Discomfort. They accounted for 46.37% of the total variance. Most items showed some degree of disordering. After collapsing response categories, all items showed ordered thresholds. The Near Activities domain showed excellent fit, whereas the Distance Activities and Mobility domain, the Mental Health and Dependency domain, and the Pain and Discomfort domain had an unsatisfactory fit. There were two items showing uniform differential item functioning. CONCLUSIONS: The four-factor structure of the VFQ-25 largely confirms the structure of the questionnaire. However, the results of this study suggest that modifications of the original VFQ-25 structure are necessary

Plasma BRAF Mutation Detection for the Diagnostic and Monitoring Trajectory of Patients with LDH-High Stage IV Melanoma

SIMPLE SUMMARY: For patients with metastatic melanoma, a rapid BRAF mutation assessment is vital to reveal the treatment options per patient. Additionally, close monitoring of the disease during treatment is essential to allow for adjustments in the treatment strategy when needed. The aim of this prospective study was to confirm the clinical validity of circulating tumor DNA (ctDNA) for minimally invasive BRAF mutation testing and treatment monitoring of metastatic melanoma patients with elevated lactose dehydrogenase serum levels. We observed that ctDNA-based BRAF mutation testing was a reliable and minimally-invasive alternative to tissue-based testing in 98% of all patients and was 100% specific. The changes in ctDNA levels during therapy appeared helpful for disease monitoring and outperformed other blood-based biomarkers in predicting treatment response. ABSTRACT: For patients with newly diagnosed metastatic melanoma, rapid BRAF mutation (mBRAF) assessment is vital to promptly initiate systemic therapy. Additionally, blood-based biomarkers are desired to monitor and predict treatment response. Circulating tumor DNA (ctDNA) has shown great promise for minimally invasive mBRAF assessment and treatment monitoring, but validation studies are needed. This prospective study utilized longitudinal plasma samples at regular timepoints (0, 6, 12, 18 weeks) to address the clinical validity of ctDNA measurements in stage IV melanoma patients with elevated serum lactate dehydrogenase (LDH > 250U/L) starting first-line systemic treatment. Using droplet digital PCR, the plasma mBRAF abundance was assessed in 53 patients with a BRAFV600 tissue mutation. Plasma mBRAF was detected in 50/51 patients at baseline (98% sensitivity; median fraction abundance of 19.5%) and 0/17 controls (100% specificity). Patients in whom plasma mBRAF became undetectable during the first 12–18 weeks of treatment had a longer progression-free survival (30.2 vs. 4.0 months; p < 0.001) and cancer-specific survival (not reached vs. 10.2 months; p < 0.001) compared to patients with detectable mBRAF. The ctDNA dynamics outperformed LDH and S100 dynamics. These results confirm the clinical validity of ctDNA measurements as a minimally invasive biomarker for the diagnostic and monitoring trajectory of patients with LDH-high stage IV melanoma