Old measures and new scores in spinal muscular atrophy patients

Introduction: A recent Rasch analysis performed on the Hammersmith Functional Motor Scale—Expanded (HFMSE) in patients with spinal muscular atrophy (SMA) identified issues impacting scale validity, redundant items, and disordered thresholds on some items. Methods: We modified the HMFSE scoring based on the Rasch analysis and on expert consensus to establish whether the traditional scoring overestimated the number of patients with changes within 2 points from baseline. Data were collected retrospectively from multicenter data sets in 255 type 2 and 3 SMA patients. Results: The mean 12‐month changes using the new and the traditional scoring system did not differ significantly (P > 0.05). The numbers of patients who improved or decreased by >2 points were also similar. Conclusions: The presence of outliers using the traditional scoring system was not due to overestimation of changes in activities that were tested bilaterally or to discrepancies in the scoring hierarchy of individual items. Muscle Nerve 52:435–437, 2015     

Outcome measures in neuromuscular disease: is the world still flat?

Valid, responsive, and meaningful outcome measures for the measurement of the impairment, activity limitations, and quality of life in patients with neuromuscular disease are crucial to identify the natural history of disease and benefits of therapy in clinical practice and trials. Although understanding of many aspects of neuromuscular diseases has advanced dramatically, the development of outcome measures has received less attention. The scales developed from Rasch theory by the PeriNomS Group represent the biggest significant shift in thought in neuromuscular outcome measures for decades. There remain problems with many of them, and further developments are required. However, incorporating them into our outcome sets for daily use and in clinical trials will lead to the more efficient capture of meaningful change and will result in better assessment of individuals and groups of patients in both clinical trials and neurological practice.     

Dimensionality and scalability of the Motor Assessment Scale (MAS)

Purpose. The Motor Assessment Scale (MAS) has shown to be a reliable and valid instrument for measuring motor functioning for stroke patients. The purpose of this paper was to study dimensionality and scalability of the instrument.

Method. A total number of 137 patients were evaluated at admission and on discharge. To study dimensionality and scalability, Partial Credit Models (PCM) were applied for the eight items in the instrument and also for the upper limb and lower limb activities separately. Studies were performed to compare subgroups such as young/old, men/women and diagnosis to examine if the items had the same meaning for the subgroups.

Results. The items showed the same ordering for admission and discharge. Infit and outfit values varied between 0.5 and 1.9 at admission and 0.5 and 1.7 on discharge.

Conclusions. We conclude that the scalability of the different items is not optimal. For some items, the top and/or bottom levels are overrepresented and for other items the middle levels tend to cluster. There seems to be a single construct except for one of the items. The instrument also showed the same meaning for the different subgroups.     

Towards an ICF-based clinical measure of functioning in people with ankylosing spondylitis: A methodological exploration

Objective. To explore whether it is possible to construct clinical measures of functioning for patients with ankylosing spondylitis (AS) by integrating information obtained across categories of the International Classification of Functioning, Disability and Health (ICF).

Methods. Sixty-eight ICF categories that were identified as relevant by patients with AS and that covered body functions, structures, and activity and participation were analysed based on the Rasch model for ordered response options. The following properties were studied: unidimensionality, reliability, fit of the ICF categories to the Rasch model, the appropriateness of the order of the response options of the ICF qualifier, and the targeting between the ICF categories and the person's abilities.

Results. After accounting for disordered thresholds and misfitting ICF categories, a clinical measure of functioning for AS was proposed that contained 64 ICF categories. On the basis of a transformation table, the raw scores obtained by adding the answers to the 64 ICF categories can be transformed to the Rasch logit scale and to a meaningful interval scale ranging from zero to 100.

Conclusion. For the first time, it has been shown that clinical measures of functioning, in principle, can be constructed based on the comprehensive ICF framework covering body functions and structures and activities and participation domains. The results of this investigation are preliminary and must be validated, but they are promising and can contribute to the acceptance and usefulness of the ICF in clinical practice.     

Goal attainment scaling: Current methodological challenges

Purpose. To validate the underlying mathematical process of Goal Attainment Scaling (GAS), as an illustration of the problems encountered by patient-generated indexes in the quest of patient-centred outcomes.

Methods. Data are simulated to represent the type of input to GAS. Rasch analysis is used to linearize the response categories for each variable associated with each goal, thus making it possible to compare the ordinal non-linear outcome of the GAS process with its linear equivalent, under the assumption of strict unidimensionality. Using a minimum clinically important difference (MCID), the level of difference between the two estimates is assessed.

Results. Over 14% of the simulated cases showed a magnitude of difference in change scores between the ordinal and linear-based GAS scores greater than the MCID. These differences were most likely to occur when patients start or finish their GAS scores at the margins of the score range, where non-linearity is greatest. The results show that the GAS process does not support mathematical operations such as multiplication. Apparent clinically meaningful changes scores can be generated solely from the non-linear nature of ordinal scores.

Conclusions. Using patient-centred approaches to measurements such as GAS presents formidable scientific challenges. Suggestions are made which, in the context of GAS applications, may overcome some of these limitations. This involves the establishment of ‘item banks’ of goals which can be pre-calibrated onto a unidimensional metric such that linearized versions of the various scores (e.g., difficulty) could be imported into the process.     

Item banking to improve, shorten and computerize self-reported fatigue: An illustration of steps to create a core item bank from the FACIT-Fatigue Scale

Fatigue is a common symptom among cancer patients and the general population. Due to its subjective nature, fatigue has been difficult to effectively and efficiently assess. Modern computerized adaptive testing (CAT) can enable precise assessment of fatigue using a small number of items from a fatigue item bank. CAT enables brief assessment by selecting questions from an item bank that provide the maximum amount of information given a person's previous responses. This article illustrates steps to prepare such an item bank, using 13 items from the Functional Assessment of Chronic Illness Therapy Fatigue Subscale (FACIT-F) as the basis. Samples included 1022 cancer patients and 1010 people from the general population. An Item Response Theory (IRT)-based rating scale model, a polytomous extension of the Rasch dichotomous model was utilized. Nine items demonstrating acceptable psychometric properties were selected and positioned on the fatigue continuum. The fatigue levels measured by these nine items along with their response categories covered 66.8% of the general population and 82.6% of the cancer patients. Although the operational CAT algorithms to handle polytomously scored items are still in progress, we illustrated how CAT may work by using nine core items to measure level of fatigue. Using this illustration, a fatigue measure comparable to its full-length 13-item scale administration was obtained using four items. The resulting item bank can serve as a core to which will be added a psychometrically sound and operational item bank covering the entire fatigue continuum.     

A Rasch Model Analysis of Alcohol Consumption and Problems Across Adolescence and Young Adulthood

Background:  Recent investigations using item response modeling have begun to conceptualize alcohol consumption, problems, and dependence as representing points along a single continuum of alcohol involvement. Such a conceptualization may be of particular benefit to measurement of alcohol involvement in adolescents, but investigations to date have been limited to adult samples and may not generalize to adolescents due to age-related developmental differences.
Methods:  This study used Rasch model analyses to examine the properties of indices of alcohol consumption and problems among 6,353 adolescents, aged 12 to 18 years, in Wave 1 of the Add Health survey. A particular focus was on whether the functioning of items changed when these adolescents were re-interviewed in Wave 3 when they were 18 to 24 years of age.
Results:  Rasch model analyses supported the unidimensionality and additive properties of the items in the Wave 1 data. Comparisons of Wave 1 and Wave 3 data indicated differential item functioning in most of the items such that items related to alcohol consumption were more severe during adolescence, whereas items related to alcohol problems were more severe in young adulthood.
Conclusions:  A valid index of alcohol involvement in adolescents can be constructed combining indices of alcohol consumption and alcohol problems. Such an index covers a range of severity and functions similarly across sex and race/ethnicity. A similar index can be constructed in young adulthood. However, the interpretation of scores must be attentive to developmental differences. In particular, for adolescents, indices of alcohol consumption are relatively closer in severity to indices of alcohol problems than they are among young adults. Thus, alcohol problems are more likely among adolescents than young adults given a similar level of drinking.     

Construct validity of two pain behaviour observation measurement instruments for young children with burns by Rasch analysis

In this study, construct validity of 2 pain behaviour observation measurement instruments for young children aged 1 to 56 months (mean age was 20 months) with burns is assessed by using Rasch analysis. The Rasch model, wherein data should meet the model expectations, assumes that an instrument measures one unidimensional construct, and focuses on the items of measurement instruments. The Pain Observation Scale for Young Children (POCIS) and the COMFORT Behaviour Scale (COMFORT-B) measure background and procedural pain as unidimensional. Adequate measurements for scientific research and daily practice can now be obtained.     

Validity of the Play Assessment for Group Settings: An evaluation of differential item functioning between children with specific language impairment and typically developing peers

Aim: The purpose of this study was to evaluate the validity evidence based on internal structure of the Play Assessment for Group Settings (PAGS). Methods: The study was conducted in day care centres by comparing observations of the free play performance of two groups of children: those with specific language impairments (SLIs) (n = 55) and those with typical language development (n = 55). The participating children were 3 to 6.5 years of age. Data were subjected to many‐faceted Rasch analyses and differential item functioning analysis was conducted to identify possible group‐specific items in the PAGS. The effect of differentially functioning items on mean play performance measurements between two subgroups of children was controlled with two different independent samples t‐tests. Results: According to the results, 80% of the test items were stable across the groups of children. Four items were harder for children with SLI, and clearly required language skills. Two items were relatively speaking easier for children with SLI, and reflected explorative functioning. The differential functioning items did not affect the ability of the PAGS to separate the children with SLI in mean play performance from their typically developing peers. Conclusion: We concluded that the PAGS is a valid tool for identifying children who have challenges in their play performance and can be used for clinical purposes. However, the slight variability supports the fact that differential item functioning should be controlled in research when using the PAGS for comparison of different subgroups in play performance.     

Construct validity of the Eating Assessment Tool (EAT-10)

Abstract

Purpose: We aimed to evaluate the construct validity of the Eating Assessment Tool (EAT-10) by determining its dimensionality, rating scale integrity, item-person match, precision and relationship with the degree of airway invasion and functional oral intake.

Methods: We conducted a retrospective analysis of patients’ EAT-10 scores. We used the Rasch rating scale model. We investigated correlations between the EAT-10 and scores on the Penetration-Aspiration Scale (PAS) and Functional Oral Intake Scale (FOIS).

Results: The median score of the EAT-10 from 127 patients was 16 of 40 (range 0–40). Confirmatory factor analysis supported unidimensionality. The 5-point rating scale categories met published criteria. Two items misfit the Rasch model and two other items displayed differential item functioning. Rasch person reliability was 0.79. Our patient cohort was divided into three person-strata. Correlations between the EAT-10 and the PAS and FOIS were weak to moderate in strength (respectively: r?=?0.26, p?=?0.0036; r?=??0.27, p?=?0.0027).

Conclusions: Our analyses identified deficits in the construct validity of the EAT-10 suggestive of a need to improve the EAT-10 to support its frequent use in clinical practice and research.

• Implications for Rehabilitation

• Swallowing disorders are associated with severe complications, such as pneumonia and malnutrition, and impose both social and psychological burdens on patients.

• The Eating Assessment Tool is a self-report instrument developed to estimate initial dysphagia severity and monitor change in patient-reported dysphagia symptoms as a response to treatment.

• This study shows that the Eating Assessment Tool has deficits in its construct validity and a need to improve the instrument to support its frequent use in clinical practice and research.