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.

[Psychometric Evaluation of the 'German Neurological Fatigue Index for Multiple Sclerosis (NFI-MS-G)' in a Sample of Rehabilitation Patients with Multiple Sclerosis]. / Psychometrische Prüfung des deutschsprachigen "Neurologischen Fragebogens zur Müdigkeit bei Multipler Sklerose (NFI-MS-G)" bei Rehabilitanden mit Multipler Sklerose.

PURPOSE: The purpose of this study was to provide a patient-reported outcome measure for people with multiple sclerosis (MS) comprehensively reflecting the construct of fatigue and developed upon the assumptions of the Rasch model. The Neurological Fatigue Index - Multiple Sclerosis (NFI-MS) is based on both a medical and patient-described symptom framework of fatigue and has been validated. Therefore, in this study the German version of the NFI-MS (NFI-MS-G) consisting of a physical and cognitive subscale and a summary scale was validated. METHOD: In this bi-centre-study, 309 people with MS undergoing outpatient rehabilitation or being≥2 months before or after their inpatient rehabilitation completed the German NFI-MS-G twice within 14-21 days together with other questionnaires. Correlation with established questionnaires and Rasch analysis were used for its validation. Additionally, psychometric properties of known-groups validity, internal consistency, test-retest reliability, measurement precision and readability were tested. Finally, the English NFI-MS and German NFI-MS-G were compared with each other to equate the language versions. RESULTS: The NFI-MS-G showed good internal construct validity, convergent and known-groups validity and internal consistency (Cronbach's alpha 0.84-0.93). The physical subscale showed minor local dependencies between items 1 and 7, 2 and 3 and 4 to 6, that could be treated by combining the respective items to testlets. Unidimensionality was found for the physical and cognitive subscales but not for the summary scale. Replacing the summary scale, a 2-domains subtest measuring the higher-order construct of fatigue was created. Good test-retest reliability (Lin's concordance correlation coefficient of 0.86-0.90) and low floor and ceiling effects were demonstrated. The NFI-MS-G was found easily readable and invariant across groups of gender, age, disease duration, timepoint and centre. CONCLUSION: The German version of the NFI-MS comprehensively represents the construct of fatigue and has adequate psychometric properties. The German version differs from the English original version with respect to a lack of unidimensionality of the summary scale and minor local dependencies of the physical subscale that could be canceled out using a testlet analysis.

Meaningful and Measurable Health Domains in Huntington's Disease: Large-Scale Validation of the Huntington's Disease Health-Related Quality of Life Questionnaire Across Severity Stages.

BACKGROUND: Although health-related quality of life is key for patients with long-term neurodegenerative conditions, measuring this is less straightforward and complex in Huntington's disease (HD). OBJECTIVES: To refine and validate a fully patient-derived instrument, the Huntington's Disease health-related Quality of Life questionnaire (HDQoL), and to elucidate health domains that are meaningful to patients' lived experience. METHODS: Five-hundred forty-one participants, from premanifest to end-stage disease, completed the HDQoL, together with generic quality-of-life measures and in-person motor, cognitive, and behavioral assessments. The psychometric properties of the HDQoL were examined using factor analysis and Rasch analysis. RESULTS: Four HDQoL domains emerged, reflecting the classical triad of HD features; they were Physical-Functional, Cognitive, and 2 different behavioral aspects, that is, the Mood-Self domain and a distinct Worries domain. These domains clarify the behavioral sequelae as experienced by patients, and all showed good to excellent internal consistency. Known-groups analyses illustrated significant and graded changes in clinical assessments and corresponding HDQoL domains across disease severity levels. Convergent and discriminant validity was demonstrated by the expected pattern of correlations between specific HDQoL domains and corresponding domain-relevant clinical assessments as well as patient-reported measures. The data demonstrate robust support for the refined HDQoL across disease stages. CONCLUSIONS: The HDQoL, with its 2 distinct behavioral domains of Mood-Self and Worries as well as the Physical-Functional and Cognitive domains, is a relevant, reliable, and valid patient-derived instrument to measure the impact of HD across all severity stages.

German translation, cultural adaptation for Austria and validation of the Neurological Sleep Index - Multiple Sclerosis (NSI-MS).

STUDY OBJECTIVES: To translate, culturally adapt, and validate the Neurological Sleep Index - Multiple Sclerosis (NSI-MS) for use in Austrian German-speaking populations with multiple sclerosis (pwMS). METHODS: Following established guidelines, the NSI-MS diurnal sleepiness (DS), non-restorative nocturnal sleep (NRNS), and fragmented nocturnal sleep (FNS) scales underwent forward-backward translation, with content and face validity, and cultural adaptation to Austria established. Construct validity was evaluated using Rasch analysis. Known-groups validity was examined, and comparisons were made with scales measuring MS fatigue, daytime sleepiness, sleep quality, anxiety, and depression. Reliability was assessed through Cronbach's alpha, Person Separation Index, Lin's concordance correlation coefficient, measurement error, and floor and ceiling effects. Data were merged with a historic English dataset for comparison between English/German language versions. RESULTS: The translation and cultural adaptation of the NSI-MS-G were successful. Pretesting involved 30 pwMS, while the validation included 400 pwMS with mild-to-severe disability. The DS, NRNS, and FNS scales exhibited good fit parameters, were unidimensional, and invariant. NSI-MS-G scales demonstrated excellent convergent and known-groups validity, internal consistency, person separation reliability, test-retest reliability, adequate measurement error, and low floor and ceiling effects. Pooling English and German datasets revealed that person estimates for the NRNS and FNS scales are equivalent across versions, unlike the DS scale. CONCLUSIONS: The NSI-MS-G demonstrates validity, reliability, and responsiveness in assessing DS, NRNS, and FNS in pwMS, generating interval-level data, and shows equivalence between its English and German versions. CLINICAL TRIAL REGISTRATION: Register: German Clinical Trials Register (DRKS); URL: https://drks.de/search/en/trial/DRKS00025573; Identifier: DRKS00025573.

Screening for the risk of job loss in multiple sclerosis (MS): development of an MS-specific Work Instability Scale (MS-WIS).

BACKGROUND: Multiple sclerosis (MS) mainly presents amongst those of working age. Depending upon the type of MS, many people embark upon a long period of managing their day-to-day work-related needs in the face of intermittent and sometimes persistent disabling symptoms. The objective of this study was to explore the concept of work instability (WI) following the onset of MS and develop a Work Instability Scale (WIS) specific to this population. METHOD: WI amongst those with MS in work was explored through qualitative interviews which were then used to generate items for a WIS. Rasch analysis was used to refine the scaling properties of the MS-WIS, which was then validated against expert vocational assessment by occupational health physiotherapists and ergonomists. RESULTS: The resulting measure is a 22-item, self-administered scale which can be scored in three bands indicating low, medium and high risk of WI (job retention) problems. The scale meets modern psychometric requirements for measurement, indicated by adequate fit to the Rasch model with absence of local dependency and differential item functioning (DIF) by age, gender and hours worked. CONCLUSIONS: The scale presents an opportunity in routine clinical practice to take positive action to reduce sickness absence and prevent job loss.

Measuring Quality of Life in Carers of People With Dementia: Development and Psychometric Evaluation of Scales measuring the Impact of DEmentia on CARers (SIDECAR).

BACKGROUND AND OBJECTIVES: A 2008 European consensus on research outcome measures in dementia care concluded that measurement of carer quality of life (QoL) was limited. Three systematic reviews (2012, 2017, and 2018) of dementia carer outcome measures found existing instruments wanting. In 2017, recommendations were published for developing reliable measurement tools of carers' needs for research and clinical application. The aim of this study was to develop a new instrument to measure the QoL of dementia carers (family/friends). METHODS: Items were generated directly from carers following an inductive needs-led approach. Carers (n = 566) from 22 English and Welsh locations then completed the items and comparator measures at three time points. Rasch, factor, and psychometric (reliability, validity, responsiveness, and minimally important differences [MIDs]) analyses were undertaken. RESULTS: Following factor analysis, the pool of 70 items was refined to three independent scales: primary SIDECAR-D (direct impact of caring upon carer QOL, 18 items), secondary SIDECAR-I (indirect impact, 10 items), and SIDECAR-S (support and information, 11 items). All three scales satisfy Rasch model assumptions. SIDECAR-D, I, S psychometrics: reliability (internal ≥ .70; test-retest ≥ .85); convergent validity (as hypothesized); responsiveness (effect sizes: D: moderate; I and S: small); MIDs (D = 9/100, I = 10/100, S = 11/100). DISCUSSION AND IMPLICATIONS: SIDECAR scales demonstrate robust measurement properties, meeting COSMIN quality standards for study design and psychometrics. SIDECAR provides a theoretically based needs-led QoL profile specifically for dementia carers. SIDECAR is free for use in public health, social care, and voluntary sector services, and not-for-profit organizations.

Assessment of the Performance of a Modified Motor Scale as Applied to Juvenile Onset Huntington's Disease.

BACKGROUND: Huntington's disease can present at almost any age but traditionally, those with an onset ≤20 years are described as having juvenile onset Huntington's disease (JOHD). They are more likely to have bradykinesia and dystonia earlier in the course of the disease. The Total Motor Score of the Unified Huntington's Disease Rating Scale (UHDRS-TMS) is often used as the principal outcome measure in clinical trials. OBJECTIVE: To identify a motor scale more suitable for JOHD patients. METHODS: A working group reviewed the UHDRS-TMS and modified it by adding four further assessment items. Rasch analysis was used to study the performance of the modified scale in 95 patients with a mean age of 19.4 (SD 6.6) years. RESULTS: The initial analysis showed a significant overall misfit to the Rasch model and a number of individual items displayed poor measurement properties: all items relating to chorea displayed significant misfit due to under-discrimination. Additionally, a number of items displayed disordered response category thresholds, and a large amount of dependency was present within the item set (96 out of 741 pairwise differences = 13%). An iterative process of scale re-structuring and evaluation was then undertaken, with a view to eliminating the largest sources of misfit and generating a set of items that would conform to Rasch model expectations. CONCLUSION: This post-hoc scale restructuring appears to provide a valid motor score that is psychometrically robust in a JOHD population. This scale restructuring offers a pragmatic solution to measuring motor function in a JOHD population, and it could provide the basis for the further iterative development of a more useful clinical rating scale for patients with JOHD.

Assessing the predictability of self-harm in a high-risk adult prisoner population: a prospective cohort study.

BACKGROUND: Prisoners are at increased risk of self-harm and when either intent is expressed, or an act of self-harm carried out, prisoners in the UK are subject to self-harm/suicide monitoring (referred to as "open ACCT" monitoring). However, there is a paucity of validated instruments to identify risk of self-harm in prisoner populations. In response to the need to support prison staff to determine who is at increased risk of self-harm or repeat self-harm, the aim of this study was to determine whether any pre-existing, standardised instruments could usefully identify future self-harm events in prisoners undergoing ACCT monitoring. METHODS: A multi-stage prospective cohort study was conducted, where the Prison Screening Questionnaire (PriSnQuest), a modified Borderline Symptom List-23 (BSL-23), Self-Harm Inventory (SHI), Patient Health Questionnaire-9 (PHQ-9) and Clinical Outcomes in Routine Evaluation - Outcome Measure (CORE-OM) instruments were administered to prisoners aged 18 and above, who were judged to be at an increased risk of self-harm (on open ACCT monitoring) during the recruitment phase. A 6-month follow-up determined self-harm occurrence since baseline, and Area-Under-the-Curve (AUC) analysis examined the ability of the instruments to predict future self-harm. RESULTS: Prison records established that 29.1% self-harmed during the follow up period, involving a total of 423 self-harm events reported from 126 individuals, followed up for 66,789 prisoner days (median 167 days; IQR 71-207.5 days). This translated to an 'event incidence' of 6.33 per 1000 prisoner days of those who had been placed upon an ACCT, or 'prisoner incidence' of 1.89 per 1000 days, with considerable variation for both gender and participating prisons. None of the summary scores derived from the selected instruments showed a meaningful ability to predict self-harm, however, exploratory logistic regression analysis of individual background and instrument items revealed gender-specific item sets which were statistically significant in predicting future self-harm. CONCLUSIONS: Prospective self-harm was not predicted by any of the pre-existing instruments that were under consideration. Exploratory logistic regression analysis did reveal gender-specific item sets, producing predictive algorithms which were statistically significant in predicting future self-harm; however, the operational functionality of these item sets may be limited.

Patient-reported outcome measures in osteoarthritis: a systematic search and review of their use and psychometric properties.

INTRODUCTION: Patient-reported outcome measures (PROM) or self-completed questionnaires have been used to report outcomes in osteoarthritis (OA) for over 35 years. Choices will always need to be made about what should be measured and, if relevant, what would be the most appropriate PROM to use. The current study aims to describe the available PROMs used in OA and their performance quality, so that informed choices can be made about the most appropriate PROM for a particular task. METHODS: The study included a systematic search for PROMs that have been in use over 17 years (period 2000-2016), and to catalogue their psychometric properties, and to present the evidence in a user-friendly fashion. RESULTS: 78 PROMs were identified with psychometric evidence available. The domains of pain, self-care, mobility and work dominated, whereas domains such as cleaning and laundry and leisure, together with psychological and contextual factors, were poorly served. The most frequently used PROMs included the Western Ontario McMaster Osteoarthritis Index, the Short Form 36 and the Knee Disability and Osteoarthritis Outcome Score which, between them, appeared in more than 4000 papers. Most domains had at least one PROM with the highest level of psychometric evidence. CONCLUSION: A broad range of PROMs are available for measuring OA outcomes. Some have good psychometric evidence, others not so. Some important psychological areas such as self-efficacy were poorly served. The study provides a current baseline for what is available, and identifies the shortfall in key domains if the full biopsychosocial model is to be explored.

Rasch analysis of the Chedoke-McMaster Attitudes towards Children with Handicaps scale.

Aim To assess whether the Chedoke-McMaster Attitudes towards Children with Handicaps (CATCH) 36-item total scale and subscales fit the unidimensional Rasch model. Method The CATCH was administered to 1881 children, aged 7-16 years in a cross-sectional survey. Data were used from a random sample of 416 for the initial Rasch analysis. The analysis was performed on the 36-item scale and then separately for each subscale. The analysis explored fit to the Rasch model in terms of overall scale fit, individual item fit, item response categories, and unidimensionality. Item bias for gender and school level was also assessed. Revised scales were then tested on an independent second random sample of 415 children. Results Analyses indicated that the 36-item overall scale was not unidimensional and did not fit the Rasch model. Two scales of affective attitudes and behavioural intention were retained after four items were removed from each due to misfit to the Rasch model. Additionally, the scaling was improved when the two most negative response categories were aggregated. There was no item bias by gender or school level on the revised scales. Items assessing cognitive attitudes did not fit the Rasch model and had low internal consistency as a scale. Conclusion Affective attitudes and behavioural intention CATCH sub-scales should be treated separately. Caution should be exercised when using the cognitive subscale. Implications for Rehabilitation The 36-item Chedoke-McMaster Attitudes towards Children with Handicaps (CATCH) scale as a whole did not fit the Rasch model; thus indicating a multi-dimensional scale. Researchers should use two revised eight-item subscales of affective attitudes and behavioural intentions when exploring interventions aiming to improve children's attitudes towards disabled people or factors associated with those attitudes. Researchers should use the cognitive subscale with caution, as it did not create a unidimensional and internally consistent scale. Therefore, conclusions drawn from this scale may not accurately reflect children's attitudes.