The development of an ICF-oriented, adaptive physician assessment instrument of mobility, self-care, and domestic life.

The objective of this study was development and psychometric testing of an adaptive, International Classification of Functioning, Disability, and Health (ICF)-oriented questionnaire to be processed by the rehabilitation physician that aids in assessing mobility, self-care, and domestic life (Moses-Physician). The intent is to develop a physician version, analogous in content to the existing patient questionnaire 'Moses-Patient'. The 58 items of Moses-Patient were converted to an external assessment format without altering the content. The data were compiled for 549 patients with musculoskeletal diseases, 212 patients with cardiac diseases, and 259 neurology rehabilitation patients. Analyses were carried out on the basis of the one-parameter item response theory (Rasch model). Effect sizes and the reliable change index were calculated to test responsiveness. Differential item functioning (DIF) was tested using DIF contrasts, equivalent to Mantel-Haenszel DIF sizes. After the item response theory analysis, 47 of 58 items remained, distributed over 12 scales. The scales are more homogeneous in content than in the patient version because of the omission of 11 items and thus do not cover the ICF categories as broadly. Model fit indices (infit and outfit mean square statistics) were in an acceptable range for all items. Cronbach's alpha was between 0.73 and 0.95. Moreover, there is clear evidence of unidimensionality and sensitivity to change of the scales of Moses-Physician. The item parameters of Moses-Physician are invariant with respect to sex and age for all scales. However, there are clear differences regarding disease groups. The Moses-Physician questionnaire is an adaptive, Rasch-scaled assessment instrument that, to a great extent, covers the contents of the ICF chapters 'mobility', 'self-care', and 'domestic life'.