Ching-Fan Sheu

Analysis and Comparison of the Psychometric Properties of Three Balance Measures for Stroke Patients

Background and Purpose— This study compared the psychometric properties of 3 clinical balance measures, the Berg Balance Scale (BBS), the Balance subscale of the Fugl-Meyer test (FM-B), and the Postural Assessment Scale for Stroke Patients (PASS), in stroke patients with a broad range of neurological and functional impairment from the acute stage up to 180 days after onset. Methods— One hundred twenty-three stroke patients were followed up prospectively with the 3 balance measures 14, 30, 90, and 180 days after stroke onset (DAS). Reliability (interrater reliability and internal consistency) and validity (concurrent validity, convergent validity, and predictive validity) of each measure were examined. A comparison of the responsiveness of each of the 3 measures was made on the basis of the entire group of patients and 3 separate groups classified by degree of neurological severity. Results— The FM-B and BBS showed a significant floor or ceiling effect at some DAS points, whereas the PASS did not show these effects. The BBS, FM-B, and PASS all had good reliability and validity for patients at different recovery stages after stroke. The results of effect size demonstrated fair to good responsiveness of all 3 measures within the first 90 DAS but, as expected, only a low level of responsiveness at 90 to 180 DAS. The PASS was more responsive to changes in severe stroke patients at the earliest period after stroke onset, 14 to 30 DAS. Conclusions— All 3 measures tested showed very acceptable levels of reliability, validity, and responsiveness for both clinicians and researchers. The PASS showed slightly better psychometric characteristics than the other 2 measures.

Trunk Control as an Early Predictor of Comprehensive Activities of Daily Living Function in Stroke Patients

Background and Purpose— Prediction of activities of daily living (ADL) functions at an early stage after a stroke is critical because it enables clinicians to set treatment programs and goals. The objective of this study was to assess the relationship between trunk control at an early stage and comprehensive ADL function (as assessed by combining basic ADL and instrumental ADL [IADL]) in patients at 6 months after stroke. Methods— A total of 169 stroke patients participated in this prospective study. Trunk control was measured with the use of the trunk control items of the Postural Assessment Scale for Stroke Patients (PASS-TC). In addition to the PASS-TC score, age, sex, type of stroke, side of hemiparesis, urinary incontinence, limb paresis (measured by the Fugl-Meyer motor test), balance (measured by the Fugl-Meyer balance test), and basic ADL (measured by the Barthel Index) were also selected as predictor variables. These variables were assessed at 14 days after stroke or earlier. The Barthel Index and Frenchay Activities Index (measuring IADL) were administered at 6 months after stroke. The sum of the standardized Barthel Index and standardized Frenchay Activities Index scores was used to assess comprehensive ADL function. Results— Multivariable stepwise linear regression analysis showed that PASS-TC score, age, Fugl-Meyer motor test score, and Barthel Index score (listed by the order of forward selection) were the strongest predictors of comprehensive ADL function. These results were internally validated with the use of the bootstrap resampling technique. The PASS-TC score alone accounted for 45% of the variance in predicting comprehensive ADL function. Results also indicated that the PASS-TC score had slightly more power in predicting comprehensive ADL function than either the Fugl-Meyer motor test score or Barthel Index score. Conclusions— The findings of this study provide strong evidence of the predictive value of trunk control on comprehensive ADL function in stroke patients. The results imply that early assessment and management of trunk control after stroke should be emphasized.

Causal inferences as perceptual judgments

We analyze how subjects make causal judgments based on contingency information in two paradigms. In the discrete paradigm, subjects are given specific information about the frequency a, with which a purported cause occurs with the effect; the frequency b, with which it occurs without the effect; the frequency c, with which the effect occurs when the cause is absent; and the frequency d, with which both cause and effect are absent. Subjects respond toP1 =a/(a+b) andP2 =c/(c+d). Some subjects’ ratings are just a function ofP1, while others are a function of ΔP =P1 -P2. Subjects’ postexperiment reports are accurate reflections of which model they use. Combining these two types of subjects results in data well fit by the weighted ΔP model (Allan, 1993). In the continuous paradigm, subjects control the purported causes (by clicking a mouse) and observe whether an effect occurs. Because causes and effects occur continuously in time, it is not possible to explicitly pair causes and effects. Rather, subjects report that they are responding to the rate at which the effects occur when they click versus when they do not click. Their ratings are a function of rates and not probabilities. In general, we argue that subjects’ causal ratings are judgments of the magnitude of perceptually salient variables in the experiment.

Distinctive Clinical Features of Mild Cognitive Impairment with Subcortical Cerebrovascular Disease

Background and Purpose: Patients with mild cognitive impairment and subcortical cerebrovascular disease (svMCI) can be isolated using criteria modified from those of Erkinjuntti et al. for subcortical vascular dementia and have poorer outcomes (cognitive deterioration, disability, institutionalization, and mortality). The aim of this study was to test which of the core (dysexecutive syndrome with relative sparing of memory, gait disorders and extrapyramidal signs) and supporting (urinary and behavioral symptoms) clinical features are most useful to recognize patients with svMCI and discriminate them from those with amnestic MCI (aMCI). Methods: Twenty-nine svMCI and 14 aMCI patients were seen in a memory clinic. Tests and scales assessing core and supporting features that independently contributed to the discrimination between svMCI and aMCI were identified with stepwise logistic regression analysis. The accuracy of the discrimination was estimated with area under the receiver operating characteristic curve and 95% confidence intervals (CIs). Results: The most accurate scales were the extrapyramidal sign scale by Richards et al. (0.75, 95% CI 0.61–0.89), letter fluency (0.75, 95% CI 0.61–0.90), irritability of the Neuropsychiatric Inventory and urinary dependence (0.66, 95% CI 0.49–0.82 for both), and digit span forward (0.59, 95% CI 0.41–0.77). The overall accuracy of a model compounding information from main and supporting features was 0.98, 95% CI 0.94–1.0. Conclusions: All the domains that are included in the clinical criteria for svMCI independently contribute to the identification of the condition. These criteria can be useful to recognize svMCI patients in clinical settings.

Comparison of Psychometric Properties of Three Mobility Measures for Patients With Stroke

Background and Purpose— This study compared the validity, responsiveness, and interrater reliability of 3 mobility measures in stroke patients from the acute stage up to 180 days after stroke onset. The 3 measures were the Rivermead Mobility Index (RMI), a modified RMI (MRMI), and the Mobility Subscale of the Stroke Rehabilitation Assessment of Movement (STREAM). Methods— The validity and responsiveness of the 3 mobility measures were prospectively examined by monitoring 57 stroke patients with the measures and the Barthel Index at 14, 30, 90, and 180 days after stroke onset. Two individual raters used the 3 measures to evaluate a different sample of 40 patients on 2 separate occasions to determine the interrater reliability. Results— The Spearman &rgr; between STREAM and MRMI was ≥0.92; the intraclass correlation coefficient (ICC, a measure of agreement) between them was ≥0.89, indicating high concurrent validity of both measures. RMI showed a moderate to high relationship and agreement with STREAM and MRMI (&rgr;≥0.78, ICC≥0.5). Responsiveness of the 3 measures was high before 90 days after stroke onset (standardized response mean ≥0.83) and low at 90 to 180 days after stroke onset (0.2≤standardized response mean≤0.4). The score changes of the 3 measures at each stage were significant (P ≤0.05), except for RMI and MRMI at 90 to 180 days after stroke onset. The interrater agreement of the 3 measures was high (ICC≥0.92). Conclusions— All 3 measures examined showed acceptable levels of reliability, validity, and responsiveness in stroke patients. The psychometric characteristics of STREAM were slightly superior to those of the other 2 measures among our patients. We prefer and recommend STREAM for measuring mobility disability in stroke patients.

Psychometric comparisons of 2 versions of the Fugl-Meyer Motor Scale and 2 versions of the Stroke Rehabilitation Assessment of Movement.

Objective. To provide empirical justification for selecting motor scales for stroke patients, the authors compared the psychometric properties (validity, responsiveness, test-retest reliability, and smallest real difference [SRD]) of the Fugl-Meyer Motor Scale (FM), the simplified FM (S-FM), the Stroke Rehabilitation Assessment of Movement instrument (STREAM), and the simplified STREAM (S-STREAM). Methods. For the validity and responsiveness study, 50 inpatients were assessed with the FM and the STREAM at admission and discharge to a rehabilitation department. The scores of the S-FM and the S-STREAM were retrieved from their corresponding scales. For the test-retest reliability study, a therapist administered both scales on a different sample of 60 chronic patients on 2 occasions. Results. Only the S-STREAM had no notable floor or ceiling effects at admission and discharge. The 4 motor scales had good concurrent validity (rho ≥ .91) and satisfactory predictive validity (rho = .72-.77). The scales showed responsiveness (effect size d ≥ 0.34; standardized response mean ≥ 0.95; P < .0001), with the S-STREAM most responsive. The test-retest agreements of the scales were excellent (intraclass correlation coefficients ≥ .96). The SRD of the 4 scales was 10% of their corresponding highest score, indicating acceptable level of measurement error. The upper extremity and the lower extremity subscales of the 4 showed similar results. Conclusions. The 4 motor scales showed acceptable levels of reliability, validity, and responsiveness in stroke patients. The S-STREAM is recommended because it is short, responsive to change, and able to discriminate patients with severe or mild stroke.

Rasch Analysis of Combining Two Indices to Assess Comprehensive ADL Function in Stroke Patients

Background and Purpose— To justify the summation of scores representing comprehensive activities of daily living (ADL) function, a Rasch analysis was performed to examine whether items of the Barthel Index (BI), assessing ADL, and items of the Frenchay Activities Index (FAI), assessing instrumental ADL, contribute jointly to a single, unidimensional construct in stroke patients living in the community. The number of scoring points of both indices was examined for their usefulness in discerning the various ability levels of ADL in these patients. Methods— A total of 245 patients at 1 year after stroke participated in this study. The BI and FAI were administered to the patient and/or the patient’s main caregiver by interview. Results— The initial Rasch analysis indicated that the middle scoring points for many items of the BI and FAI could be collapsed to allow only dichotomous response categories. All but 2 items of the FAI, social occasions and walking outside, fitted the model’s expectations rather well. These 2 items were excluded from further analysis. A factor analysis performed on the residuals of the Rasch-transformed scores recovered no dominant component. These results indicate that the combined 23 dichotomous items of the BI and FAI assess a single unidimensional ADL function. Conclusions— A clinically useful assessment of the comprehensive ADL function of patients at or later than 1 year after stroke can be obtained by combining the items of the BI and FAI (excluding 2 FAI items) and simplifying the responses into dichotomous categories. It is also demonstrated that the items of the new scale measure comprehensive ADL function as a single unidimensional construct when assessed at 1 year after stroke.

Psychometric properties of the sensory scale of the Fugl-Meyer Assessment in stroke patients

Objective: To examine the psychometric properties of the sensory scale of the Fugl-Meyer Assessment (FMA-S) in stroke patients with a broad range of neurological and functional impairment at times from 14 to 180 days after stroke. Subjects: A total of 176 first stroke patients consecutively admitted to a university based medical centre. Design: This prospective, longitudinal investigation was based on data collected at 14, 30, 90 and 180 days after stroke. Main outcome measures: Reliability (inter-rater reliability and internal consistency), validity (convergent and predictive validity) and responsiveness of the FMA-S were examined. Results: The inter-rater agreement of the total score of the FMA-S was excellent, with an intraclass correlation coefficient of 0.93. The Cronbachs alphas of the FMA-S at four time points after stroke ranged from 0.94 to 0.98, indicating excellent internal consistency. However, the FMA-S showed a significant ceiling effect (more than 44.4% of the subjects achieving the highest score), poor to moderate inter-rater reliability for light touch items (weighted kappa ranging from 0.30 to 0.55), low to moderate validity (Spearmans rho ranging from 0.29 to 0.53), and low to moderate responsiveness (standardized response mean ranging from 0.27 to 0.67) at different post-stroke stages of recovery. Conclusions: The psychometric properties of the FMA-S in measuring sensory function do not support its clinical use in stroke patients. Further studies on methods to improve the psychometric properties of the FMA-S are needed.

Using SAS PROC NLMIXED to fit item response theory models

Researchers routinely construct tests or questionnaires containing a set of items that measure personality traits, cognitive abilities, political attitudes, and so forth. Typically, responses to these items are scored in discrete categories, such as points on a Likert scale or a choice out of several mutually exclusive alternatives. Item response theory (IRT) explains observed responses to items on a test (questionnaire) by a person’s unobserved trait, ability, or attitude. Although applications of IRT modeling have increased considerably because of its utility in developing and assessing measuring instruments, IRT modeling has not been fully integrated into the curriculum of colleges and universities, mainly because existing general purpose statistical packages do not provide built-in routines with which to perform IRT modeling. Recent advances in statistical theory and the incorporation of those advances into general purpose statistical software such as the Statistical Analysis System (SAS) allow researchers to analyze measurement data by using a class of models known as generalized linear mixed effects models (McCulloch & Searle, 2001), which include IRT models as special cases. The purpose of this article is to demonstrate the generality and flexibility of using SAS to estimate IRT model parameters. With real data examples, we illustrate the implementations of a variety of IRT models for dichotomous, polytomous, and nominal responses. Since SAS is widely available in educational institutions, it is hoped that this article will contribute to the spread of IRT modeling in quantitative courses.

Development and Validation of a Short Form of the Fugl-Meyer Motor Scale in Patients With Stroke

Background and Purpose— The 50-item Fugl-Meyer motor scale (FM) is commonly used in outcome studies. However, the lengthy administration time of the FM keeps it from being widely accepted for routine clinical use. We aimed to develop a short form of the FM (the S-FM) with sound psychometric properties for stroke patients. Methods— The FM was administered to 279 patients. It was then simplified based on expert opinions and the results of Rasch analysis. The psychometric properties (including Rasch reliability, concurrent validity, predictive validity, and responsiveness) of the S-FM were examined and were compared with those of the FM. The concurrent validity and responsiveness of the S-FM were further validated in a sample from the Netherlands. Results— We selected 6 items for each subscale to construct a 12-item S-FM. The S-FM demonstrated high Rasch reliability, high concurrent validity with the original scale, moderate responsiveness, and moderate predictive validity with the comprehensive activities of daily living function. The S-FM also showed sufficient concurrent validity and responsiveness on the Dutch sample. Conclusions— Our results provide strong evidence that the psychometric properties of the S-FM are comparable with those of the FM. The S-FM contains only 12 items, making it a very efficient measure for assessing the motor function of stroke patients in both clinical and research settings.