[Validation of the computerized adaptive assessment procedure RehaCAT related to functional and mental strain in a sample of rehabilitation patient suffering from musculoskeletal diseases]

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.

[Validity and responsiveness of the Scales for the Assessment of Functioning at Work]

The Scales for the Assessment of Functioning at Work (SE-FFB) allow for an ICF-oriented assessment of patient reported work performance and symptoms at work. The aim of the study is to test convergent end discriminate validity through correlations with measures that are typically applied in rehabilitation and responsiveness by means of description of the change in the course of rehabilitation (t0=beginning of the rehabilitation, t1=3 months after rehabilitation). The sample comprises 249 rehabilitation patients with musculoskeletal diseases. The correlations of the SE-FFB with the criteria of convergent and discriminate validity are in accordance with the expectations. For women medium effects were found, indicating better work performance and fewer symptoms 3 months after rehabilitation, for men the effects were small. The SE-FFB allows for a reliable, valid and responsive assessment of the working situation.

[Resources and self-management skills in multiple sclerosis patients - can the scale structure of the questionnaire FERUS be replicated?]

BACKGROUND

To assess resources and self-management skills the generic questionnaire FERUS was developed by Jack (2007) and validated and standardized in a sample of psychosomatic patients and of healthy people. The aim of this study was the psychometric review of the FERUS with a sample of patients with Multiple Sclerosis (MS).

METHODS

The dimensional structure identified by Jack was replicated in an exploratory factor analyses as well as tested in a confirmatory factor analyses and the discrimination ability of the scales was examined.

RESULTS

Jack's results of the exploratory factor analyses and scale analyses were replicated essentially. After elimination of non-theory-compliant items, differentiation of the construct "motivation for change" and insertion of a second-order construct "self-management skills" a good confirmatorical model fit could be achieved.

CONCLUSION

The FERUS can be used for MS patients. The consideration of optimization proposals allows higher construct validity and a more economical use of FERUS.

[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]

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.

[Examination of calibrated item banks for the assessment of work capacity in an outpatient sample of cardiological patients]

BACKGROUND

Work capacity is a major outcome variable in cardiological rehabilitation. However, there is a lacks of capacious and economic assessment instruments for work capacity. By developing item response theory based item banks a first step to close this gap is done. The present study aims to validate the work capacity item banks for cardiovascular rehabilitation inpatients (WCIB-Cardio) in a sample of cardiovascular rehabilitation outpatients. Additionally, we examined differences between in- and outpatients with regard to their work capacity.

METHODS

Data of 283 cardiovascular rehabilitation inpatients and 77 cardiovascular rehabilitation outpatients were collected in 15 rehabilitation centres. The WCIB-Cardio contains the 2 domains of "cognitive work capacity"(20 items) and "physical work capacity"(18 items). Validation of the item bank for cardiological outpatients was conducted with separate Rasch analysis for each domain.

RESULTS

For the domain of cognitive work capacity 10 items showed satisfying quality criteria (Rasch reliability=0.71; overall model fit=0.07). For the domain of physical work capacity good values for Rasch-reliability (0.83) and overall -model fit (0.65) could be proven after exclusion of 3 items. Unidimensionality and a broad ability spectrum could be covered for both domains. With regard to content, outpatients evaluate themselves less burdened than inpatients for the domain of cognitive work capacity (‾X outpatient =-2.06 vs. ‾X inpatient =-2.49; p<0.07) similarly for the domain of physical work capacity (‾X outpatient =-3.68 vs. ‾X inpatient =-2.88; p<0.01).

DISCUSSION

With the WCIB-Cardio II there is a precondition to develop self-report instruments of work capacity in cardiological in- and outpatients.

Compact x-ray microscope for the water window based on a high brightness laser plasma source

We present a laser plasma based x-ray microscope for the water window employing a high-average power laser system for plasma generation. At 90 W laser power a brightness of 7.4 x 10(11) photons/(s x sr x μm(2)) was measured for the nitrogen Lyα line emission at 2.478 nm. Using a multilayer condenser mirror with 0.3 % reflectivity 10(6) photons/(μm(2) x s) were obtained in the object plane. Microscopy performed at a laser power of 60 W resolves 40 nm lines with an exposure time of 60 s. The exposure time can be further reduced to 20 s by the use of new multilayer condenser optics and operating the laser at its full power of 130 W.

[Adaptive testing in rehabilitation: a way to economic assessment of patients' attributes]

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.

The new rasch-based depression screening (DESC): Evaluation and validation in different patient groups and a large German population sample

Introduction

Comorbid depression in somatic illness is highly prevalent. However, most depression questionnaires show violation of unidimensionality and hypersensitivity of items.

Objectives

The Depression Screening (DESC) is a new self-rating scale for the measurement of depression severity that we developed from a calibrated Rasch-homogeneous item bank (N = 367) to improve short depression assessment in patients beyond psychiatric settings.

Aim

To present data for both parallel forms (10 questions each) of the DESC, and to examine its Rasch model qualities in different patient groups and a representative German general population sample.

Methods

Patient groups with depression, heart disease, neurological or otolaryngological disease (N = 333) were investigated with the DESC accompanied by diagnostic interviews and established depression scales. The demographic sample (N = 2509) was interviewed face to face, too. Adherence to Rasch model assumptions was determined with analysis of model fit, and further measures. Norm values were calculated.

Results

Both DESC versions feature different but highly correlated item sets. Cut-off scores with good sensitivity (0.82, 0.81) and specificity (0.78, 0.77) for the diagnosis of an affective disorder were developed with ROC analyses. No serious Differential Item Functioning in Rasch analyses for both scales was found. In the German validation sample the Rasch dimension “depression” explained 68.5% and 69.3% respectively of the variance. Validity was determined through sufficient intercorrelations with other scales (e.g. BDI, HADS).

Conclusions

Our studies support the good psychometric RASCH qualities of both DESC forms and offer important advancements in depression screening being of use for time-limited clinical and research applications.