Improving outcome measures in late onset Pompe disease: Modified Rasch-Built Pompe-Specific Activity scale

Background and purpose The Rasch-Built Pompe-Specific Activity (R-PAct) scale is a patient-reported outcome measure specifically designed to quantify the effects of Pompe disease on daily life activities, developed for use in Dutch- and English-speaking countries. This study aimed to validate the R-PAct for use in other countries. Methods Four other language versions (German, French, Italian, and Spanish) of the R-PAct were created and distributed among Pompe patients (≥16 years old) in Germany, France, Spain, Italy, and Switzerland and pooled with data of newly diagnosed patients from Australia, Belgium, Canada, the Netherlands, New Zealand, the USA, and the UK and the original validation cohort (n = 186). The psychometric properties of the scale were assessed by exploratory factor analysis and Rasch analysis. Results Data for 520 patients were eligible for analysis. Exploratory factor analysis suggested that the items separated into two domains: Activities of Daily Living and Mobility. Both domains independently displayed adequate Rasch model measurement properties, following the removal of one item ("Are you able to practice a sport?") from the Mobility domain, and can be added together to form a "higher order" factor as well. Differential item functioning (DIF)-by-language assessment indicated DIF for several items; however, the impact of accounting for DIF was negligible. We recalibrated the nomogram (raw score interval-level transformation) for the updated 17-item R-PAct scale. The minimal detectable change value was 13.85 for the overall R-PAct. Conclusions After removing one item, the modified-R-PAct scale is a valid disease-specific patient-reported outcome measure for patients with Pompe disease across multiple countries

The disease burden of Multiple Sclerosis from the individual and population perspective: Which symptoms matter most?

MS symptoms affect many functional domains. Knowing the specific impact of symptoms on health-related quality of life (HRQoL) is vital for successful disease and symptom management in MS. We aimed at investigating how specific MS symptoms contribute to the disease burden in individuals and from a population perspective. We included 855 Swiss Multiple Sclerosis Registry participants with a relapsing-remitting form (RRMS) or a progressive form (PMS). HRQoL was measured with the EuroQol 5-Dimension EQ-5D-index and EQ-Visual Analogue Scale (EQ-VAS) on 0-100% scales. Their associations with 20 symptoms, socio-demographic and clinical information were explored in median regression models, stratified by RRMS and PMS. We included 611 participants with RRMS and 244 with PMS. In RRMS, gait (-6.5%) and balance problems (-5.1%) had the largest EQ-5D-index reductions, and were also important at the population level (frequencies 45% and 52%). Fatigue, depression, and spasticity (frequencies 74.1%, 31%, 38%) also contributed to the population disease burden. In PMS, spasticity, paralysis, and bowel problems had the largest impact on EQ-5D-index, both at the individual and population levels. The largest impact on EQ-VAS at population level was associated in RRMS with balance problems, depression, dizziness, and spasticity, while in PMS with weakness, pain, and paralysis. While HRQoL at population level is most affected by balance problems, spasticity, and depression in RRMS, the biggest HRQoL losses in PMS are caused by spasticity, paralysis, weakness, and pain. Many symptoms with the largest effects in individuals substantially contribute to the population disease burden