Impact on participation and autonomy questionnaire: internal scale validity of the Swedish version for use in people with spinal cord injury.

OBJECTIVE To evaluate aspects of internal scale validity and reliability of the Swedish version of the Impact on Participation and Autonomy questionnaire (IPA-S) for use in people with spinal cord injury. SUBJECTS A total of 161 persons with spinal cord injury. METHOD IPA-S psychometric properties were evaluated using Rasch rating scale analysis. RESULTS The results show that the IPA-S has 27 items for perceived participation and 6 items for perceived problems with participation, indicating 2 underlying unidimensional constructs for use in people with spinal cord injury, after removal of misfitting items. The established hierarchical order of the item calibration values in both scales appeared logical and the distances between the items, with a few exceptions in the problem scale, were appropriate. Both scales demonstrated good separation reliability. The range of item calibration values in both scales did not fully cover the range of measures of persons' perceived participation and problems thereof. CONCLUSION The psychometric properties of IPA-S are promising and indicate that IPA-S has potential to be developed further.