[Validation of the computerized adaptive assessment procedure RehaCAT related to functional and mental strain in a sample of rehabilitation patient suffering from musculoskeletal diseases]. / Validierung der computeradaptiven Assessmentprozedur RehaCAT hinsichtlich funktionaler und psychischer Belastungen bei Rehabilitanden mit muskuloskelettalen Erkrankungen.

The Rasch-based, computerized adaptive assessment procedure RehaCAT allows to assess the ICF-oriented dimensions "activities in daily living", "functionality upper extremities" and "functionality lower extremities" as well as "depression" economically and reliably in orthopaedic rehabilitation patients. This validation study aimed at analyzing the multivariate association of the RehaCAT dimensions with the commonly applied ODI, SF-12 and HADS-D assessment scales in a sample of rehabilitation patient suffering from musculoskeletal diseases (spine disease: 58,7%). By means of structural equation modeling high convergent and divergent validity of the RehaCAT dimensions could be proven in a sample of N=184 rehabilitation patients (71,2% inpatient and 28,8% outpatient). In the resulting model between 41% (functionality upper extremities) and 76% (activities in daily living) of the RehaCAT dimensions could be explained mainly by the theoretical assumed predictor constructs. Because of its psychometric foundation, economy and validity, the RehaCAT provides an optimal basis to assess central ICF-oriented constructs in orthopaedic rehabilitation.

[Confirmatory analysis of the dimensional structure of the ODI, the SF-12 and the HADS-D scales in a sample of rehabilitation patients with musculoskeletal diseases]. / Konfirmatorische Prüfung der dimensionalen Struktur des Oswestry Disability Index, des SF-12 und der HADS-D bei Rehabilitanden mit muskuloskelettalen Erkrankungen.

This study aimed at confirmatory testing the factorial structure of the established assessment instruments ODI, SF-12 and HADS-D by means of structural equation modeling in a sample of n=184 rehabilitation patients with musculo-skeletal diseases. According to local and global fit indices for each instrument an acceptable to good fit to the underlying theoretical model could be verified. For the ODI as well as for the HADS-D only single weak item-construct associations indicated shortcomings in the assumed model structure. For the SF-12 the constructs "physical health" and "mental health" could be validated after defining the additional first order factors "role - physical", "role - emotional" and "well-being", respectively. In general, the study findings proved the factorial validity of the instruments. Additionally, specific measurement properties on item and structural level could be identified which might enhance the understanding of construct definitions in rehabilitation patients with musculoskeletal diseases.

[Adaptive testing in rehabilitation: a way to economic assessment of patients' attributes]. / Adaptives Testen in der Rehabilitation - ein Weg zur ökonomischen Erhebung von Patientenmerkmalen*

For diagnostics and outcome measurement in clinical rehabilitation a multitude of questionnaires is used. In order to gain comparability of the diagnostic findings, generally, the same information is gathered of all patients, regardless of their state of health or how severely ill they are, by using identical groups of items. In this kind of assessment it is, however, problematic that (a) the assessment instrument usually only allows for adequate and reliable diagnostics of patients who suffer from injuries or illnesses of medium severity, and (b) that an uneconomic data collection is required because of an extensive set of items which may in individual cases be uninformative and unnecessary. This article shows how data assessment can be adjusted to the individual handicaps of the patient by using adaptive or tailored testing. Thus it can be ensured that the testing becomes more economical and results more precise. Furthermore, a high acceptance by the patients participating in the data collection can be achieved, as the test items submitted fit the ability of the patients adequately. Yet, adaptive test systems require a complex and very careful psychometrical development of the assessment procedure in such a way that in spite of presenting different items to patients, diagnostic outcomes are comparable between patients and for different points in time (e. g., pre-post comparison). This article shows the steps of development that have to be accomplished in order to set up a psychometrically sound adaptive test procedure. Moreover, it shows how its usage in the area of medical rehabilitation can be profitable for handlers and patients.

[Properties and benefits of applying the Rasch model in clinical diagnostics]. / Eigenschaften und Nutzen des Rasch-Modells in der klinischen Diagnostik.

In medical rehabilitation settings the use of appropriate assessment instruments is essential in many ways. A high quality of psychometric scales has to be ensured in order to allow for an appropriate interpretation of diagnostical data as well as for the evaluation of treatment outcomes and for quality assurance within rehabilitation clinics. Assessment scales developed by means of Rasch analysis possess desirable properties, especially because person parameters reach interval level by definition, and the assumption of only one latent dimension suffices to predict respondents behaviour sufficiently. Accordingly, Rasch scales are strictly one-dimensional and thus allow for unambiguous interpretation of diagnostic results. In this article it is shown which specific properties characterize Rasch scales and how Rasch analysis can be used in order to allow for a more differentiated and clinically meaningful data interpretation and to enhance analysis of clinical data.

Limits for the central production of Theta+ and Xi(--)pentaquarks in 920-GeV pA collisions.

We have searched for Theta+(1540) and Xi(--)(1862) pentaquark candidates in proton-induced reactions on C, Ti, and W targets at midrapidity and square root of s = 41.6 GeV. In 2 x 10(8) inelastic events we find no evidence for narrow (sigma approximately 5 MeV) signals in the Theta+ --> pK0(S) and Xi(--) --> Xi- pi- channels; our 95% C.L. upper limits (UL) for the inclusive production cross section times branching fraction B dsigma/dy/(y approximately 0) are (4-16) mub/N for a Theta+ mass between 1521 and 1555 MeV, and 2.5 mub/N for the Xi(--). The UL of the yield ratio of Theta+/Lambda(1520) < (3-12)% is significantly lower than model predictions. Our UL of B Xi(--)/Xi(1530)0 < 4% is at variance with the results that have provided the first evidence for the Xi(--).

[Item response theory and its application in neurology. Measurement of activity limitations in neurologic patients]. / Item-response-Theorie und deren Anwendung in der Neurologie Messung von Aktivitätseinschränkungen neurologischer Patienten.

This article is concerned with the measurement of activity limitations in neurologic patients and with the application of the item response theory (IRT), especially the Rasch analysis, in analyzing activity ratings. Activity limitations of 166 patients with different neurologic disorders (e.g., stroke, traumatic brain injury) were assessed with the Functional Independence Measure (FIM) during their stay in a rehabilitation hospital. Data analysis was performed with the Rasch model, which allows testing the psychometric qualities of the FIM. Results indicate that the FIM has good psychometric qualities. However, results also show that the 18 FIM items define two statistically and clinically different indicators. Thirteen items define disability in motor functions. Five items define disability in cognitive functions. Separate analyses of the two scales help to improve the psychometric quality of the FIM.

[Agreement on the Barthel Index. A rapid analysis of other and self-assessment in elderly stroke patients]. / Beurteilungsübereinstimmung beim Barthel-Index. Eine Rasch-Analyse der Fremd- und Selbstbeurteilungen älterer Schlaganfall-Patienten.

The relationship between staff and patient ratings of activity restrictions (Barthel Index, BI) was investigated in 120 elderly stroke patients (on average 78 years old) using the Rasch model and the rating scale analysis. In addition, the relationship between the rated activity restrictions and measures from the Geriatric Assessment was analyzed. We found good patient-staff agreement (r = 0.90) with the poorest agreement in the item "bathing" of the BI. There was also a highly significant correlation between staff and patient ratings and the Tinetti Gait and Balance Scales (r = 0.72 and r = 0.76, respectively). Correlations between other measures of the Geriatric Assessment and the rated activity restrictions were low explaining less than 8% of variance. Our findings merit the use of patient ratings of activity restrictions in stroke outcome research. However, self-ratings of activity restrictions were measured by an unstructured interview and it cannot be ruled out that this method had an influence on the correlation between self-rating and staff rating.

Telepresence in videocommunications: a study on stereoscopy and individual eye contact.

We conducted two experiments to investigate how stereoscopy and technologies that allow individual eye contact affect the impression of telepresence in video-conferencing. Telepresence is defined as the degree to which participants of a telemeeting get the impression of sharing space with the remote site. Results revealed, among other things, that stereoscopy increases telepresence and makes videoconferencing more attractive. In addition, we found that reduced eye contact angles enhance the recognizability of individually addressed nonverbal signals. However, a setup that eliminates horizontal and vertical eye contact angles seems to be advantageous only in conferences with more than two persons per site.