Craig A. Velozo

Awareness and compensation in postacute head injury rehabilitation

Deficits in awareness caused by brain Injury can be divided into three types: deficits in intellectual awareness, deficits in emergent awareness, and deficits in anticipatory awareness. The presence or absence of an awareness deficit and the type of awareness deficit will determine the kinds of comp

A comparison of the separation ratio and coefficient alpha in the creation of minimum item sets.

BackgroundShort-form outcomes measures are becoming common in response to demands for increased efficiency in health care. This study examines Rasch measurement as an aid to selecting items for short form tests. The focus of this paper is on maintaining test quality while reducing items. The separation ratio (SR) aids item reduction by indicating how removing items impacts measurement precision. Results of the SR and coefficient &agr; are compared. ObjectivesTo demonstrate the use of Rasch measurement to shorten clinical outcomes measures and to compare the separation ratio and coefficient &agr; in evaluating when item reduction improved efficiency without sacrificing measurement precision. Research DesignRetrospective analysis of existing health outcomes data. SubjectsA convenience sample of 58 patients receiving cataract surgery. MeasuresThe 14 items of the VF-14 (a measure of visual functioning), the published subset of items from this test (the VF-7), and 5 other 7-item combinations of the items. ResultsThe largest coefficient &agr; was obtained from the VF14 (.84) while the largest separation ratio (2.67) was obtained from the 7-item subtest with the reduced rating scale. ConclusionsThis study demonstrated one way that Rasch measurement can be helpful in selecting items for minimum item sets while maintaining test precision. Both &agr; and the separation ratio provide information about how a sample performed with a given test although variations in measurement precision may not always be detected with &agr;.

Development of a Behind‐the‐Wheel Driving Performance Assessment for Older Adults

Many driving rehabilitation specialists and researchers have emphasized the “on-road” driving assessment as the most appropriate method to determine driving performance. Difficulty arises with consensus surrounding the standardization of the clinical assessment and on-road assessment protocols. This research was designed to evaluate the psychometric properties and clinical utility of a standardized method for behind-the-wheel (BTW) driving assessment for older adults. Ninety-five older adults from the Gainesville, Fla, area were assessed for BTW performance by driving rehabilitation specialists. A global rating (criterion) of overall driving competence was correlated with an objective performance score. The global rating was found to be significantly correlated with the driving performance score (r = 0.84, P < .001). Intraclass correlation coefficients (ICC) were calculated for interrater (0.94) and test-retest (0.95) reliability for the performance score. Internal consistency for the BTW assessment was 0.94. These assessment methods and the course design provide a valid and reliable outcome measure of driving performance for older adults.

Developing meaningful Fear of Falling Measures for community dwelling elderly.

Velozo CA, Peterson EW: Developing meaningful fear of falling measures for community dwelling elderly. Am J Phys Med Rehabil 2001:80:662–673. Objective: The objective of this study is to demonstrate how a Rasch analytic approach can be used to create fear of falling measures that remain connected to the meaningful descriptions provided by the instrument items. Design: The University of Illinois at Chicago Fear of Falling Measure was developed using focus groups and consists of 19 common activities designed to represent an increasing level of concern about falling among older adults. Results: Rasch analysis of responses from 106 community dwelling elderly revealed that the two middle rating scale categories (a little worried and moderately worried) were not being used in the expected fashion. After modification of the rating scale, Rasch analysis showed that the three items causing the least worry (get dressed, get on/off toilet, and get in/out of bed) were statistically erratic. Conclusion: Final analysis demonstrated that the remaining 16 items represented a unidimensional construct that, in general, supported the original expected item difficulty hierarchy. Because person and item measures were calibrated on the same linear scale person measures are translatable to item descriptions. This connection provides meaning to the numeric values obtained from the instrument and provides a basis for setting clinically relevant criteria for interventions.

Conceptualizing functional cognition in stroke.

Background. Up to 65% of individuals demonstrate poststroke cognitive impairments, which may increase hospital stay and caregiver burden. Randomized stroke clinical trials have emphasized physical recovery over cognition. Neuropsychological assessments have had limited utility in randomized clinical trials. These issues accentuate the need for a measure of functional cognition (the ability to accomplish everyday activities that rely on cognitive abilities, such as locating keys, conveying information, or planning activities). Objective. The aim of the study was to present the process used to establish domains of functional cognition for development of computer adaptive measure of functional cognition for stroke. Methods. Functional cognitive domains involved in identifying relevant neuropsychological constructs from the literature were conceptualized and finalized after advisory panel feedback from experts in neurology, neuropsychology, aphasiology, clinical trials, and epidemiology. Results. The following 17 domains were proposed: receptive aphasia, expressive aphasia, agraphia, alexia, calculation, visuospatial, visuoperceptual, visuoconstruction, attention, language usage, executive functions, orientation, processing speed, memory, working memory, mood, awareness and abstract reasoning. The advisory panel recommended retaining the first 12 domains. Recommended changes included: to address only encoding and retrieval of recent information in the memory domain; to add domains for limb apraxia and poststroke depression; and to keep orientation as a separate domain or reclassify it under memory or attention. The final 10 domains included: language, reading and writing, numeric/calculation, limb praxis, visuospatial function, social use of language, emotional function, attention, executive function, and memory. Conclusion. Conceptualizing domains of functional cognition is the first step in developing a computer adaptive measure of functional cognition for stroke. Additional steps include developing, refining, and field-testing items, psychometric analysis, and computer adaptive test programming.

Unidimensionality and bandwidth in the Center for Epidemiologic Studies Depression (CES-D) Scale

In this study, we compared classical test theory (CTT) and item response theory (IRT) approaches in analyzing the Center for Epidemiological Studies Depression (CES–D) Scale (Radloff, 1977). Standard item analyses, as well as Rasch (1960) analyses, both revealed item departures from unidimensionality in a sample of 2,455 older persons responding to the CES‐D. Positive affect items in the scale performed poorly overall, their removal reducing the scales bandwidth only slightly. Modeling depression scores derived from Rasch measures and raw totals showed subtle but important differences for statistical inference. The assessment of depressive risk was slightly enhanced by using 16-item scale measures obtained from the results of the Rasch analysis as the dependent variable. Confirmatory factor analysis and parallel analysis verified the advantages of removing positively worded items. IRT and CTT techniques proved to be complementary in this study and can be usefully combined to improve measuring depression.

Longitudinal Stability of the Fugl-Meyer Assessment of the Upper Extremity

OBJECTIVE To investigate the longitudinal stability of the Fugl-Meyer Assessment (FMA) of the upper-extremity item difficulties by using Rasch analysis. DESIGN Secondary analysis of existing data from a cohort longitudinal study of stroke recovery. SETTING University research center. PARTICIPANTS A total of 377 people, ages 69.2+/-11.2 years, to whom the assessment was administered at 2 weeks and 6 months poststroke. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Differential item function analysis performed by using the Winsteps software program examined whether the item difficulty hierarchical order of a modified 30-item FMA for the upper extremity (reflex items removed) was invariant across 2 testing occasions. RESULTS Only 2 items (shoulder flexion to 180 degrees, movement with normal speed) showed large differences in test-retest item difficulty calibration. Item instability had no practical consequences on the longitudinal measurement of person ability. CONCLUSIONS The 30-item assessment shows a longitudinally stable item difficulty order and is valid for measuring volitional arm motor ability over time.

Measurement structure of the Wolf Motor Function Test: implications for motor control theory.

Background. Tools chosen to measure poststroke upper-extremity rehabilitation outcomes must match contemporary theoretical expectations of motor deficit and recovery because an assessment’s theoretical underpinning forms the conceptual basis for interpreting its score. Objective. The purpose of this study was to investigate the theoretical framework of the Wolf Motor Function Test (WMFT) by (1) determining whether all items measured a single underlying trait and (2) examining the congruency between the hypothesized and the empirically determined item difficulty orders. Methods. Confirmatory factor analysis (CFA) and Rasch analysis were applied to existing WMFT Functional Ability Rating Scale data from 189 participants in the EXCITE (Extremity Constraint-Induced Therapy Evaluation) trial. Fit of a 1-factor CFA model (all items) was compared with the fit of a 2-factor CFA model (factors defined according to item object-grasp requirements) with fit indices, model comparison test, and interfactor correlations. Results. One item was missing sufficient data and therefore removed from analysis. CFA fit indices and the model-comparison test suggested that both models fit equally well. The 2-factor model yielded a strong interfactor correlation, and 13 of 14 items fit the Rasch model. The Rasch item difficulty order was consistent with the hypothesized item difficulty order. Conclusion. The results suggest that WMFT items measure a single construct. Furthermore, the results depict an item difficulty hierarchy that may advance the theoretical discussion of the person ability versus task difficulty interaction during stroke recovery.

Worker Role Interview: Toward Validation of a Psychosocial Work-Related Measure

Three studies were conducted to examine the validity of the Worker Role Interview (WRI), a semi-structured interview and rating scale designed to assess psychosocial capacity for return to work in injured workers. The first Rasch analysis study of 119 work-hardening clients with low back pain showed that scale items worked together to measure unidimensional construct, except for two work-environment items (work setting and boss); and the items were logically ordered representing the least to most psychosocial capacity for return to work. The second Rasch analysis study involved a refined scale (including redefinition of environment items to reflect the workers perception of the environment) applied to 55 work-hardening clients with diverse injuries. All items except perception of boss defined a unidimensional construct. The ordering of items was similar to that in the first study and similar across two different diagnostic groups (low back and upper extremity injuries), indicating the scale was sample invariant. The third study of 42 work-hardening clients examined the predictive validity of the WRI. A logistic regression, which included demographic variables (chronicity, diagnosis, number-of-surgeries, attorney involvement and age), showed that none of the variables predicted return to work (odds ratio ranged from 0.3–1.0). This initial series of studies present a theoretically based instrument, which shows promising psychometric qualities. While the predictive study indicated that the WRI was not useful in predicting return to work, this finding may have been a function of the small n-size in the study or that the WRI may mediate its effect through other variables.

Minimum Detectable Change of the Berg Balance Scale and Dynamic Gait Index in Older Persons at Risk for Falling

Background:The Berg Balance Scale (BBS) and the Dynamic Gait Index (DGI) are often the central components of the physical therapy evaluation to identify older adults at risk of falling. Purpose:The purpose of this study was to use the standard error of measurement to investigate the minimal detectable change associated with these clinical instruments. Methods:A sample of 42 community dwellers (older than 65 years) with a history of falls or near falls was evaluated with the BBS and DGI. Evaluations were videotaped and later rescored by 2 experienced physical therapists. Results:The mean initial BBS was 39 points (SD = 8.9, range 17–53). Rescored mean value was 40 points (SD = 8.8, range 19–55). The DGI mean initial value was 12.9 (SD = 4.5, range 3–21), and the rescored mean was 12.7 (SD = 4.6, range 4–22). MDC95% values were 6.5 BBS and 2.9 DGI points, respectively. Conclusion:These results suggest that a change of 6.5 point in the BBS and 2.9 points in the DGI is necessary to be 95% confident that genuine change in function has occurred between 2 assessments. This information is important for assessing and monitoring progress and guiding treatment for community dwellers at high risk of falling.