Our first objective was to make an inventory of available instruments for the assessment of disabilities in gait and related activities in patients with rheumatic disorders. Our second aim was to investigate which of these instruments have acceptable methodological quality with regard to reliability and validity. Our third aim was to investigate the assumption that the evaluation of convergent construct validity results in stronger correlations when validated against a more similar construct.
A computer-aided literature search (1982-2001) of several databases was performed to identify studies focusing on the clinimetric properties of instruments to assess impairments in function in patients with rheumatic disorders. Data on intra-rater reliability, inter-rater reliability and convergent construct validity were extracted in a standardized manner and compared to a priori defined criteria.
In total 78 instruments were eligible. Intra-observer reliability was investigated for 28 instruments and only 7 demonstrated good reliability as well as good validity. Surprisingly, the convergent construct validation against a similar construct resulted often in lower correlations than validation against a less similar construct.
Based on the available information, the Rheumatoid Arthritis Quality of Life Scale and the Health Assessment Questionnaire seem to be the best instruments for assessing disabilities in gait and related activities in patients with rheumatic disorders.