THE GRONINGEN ACTIVITY RESTRICTION SCALE FOR MEASURING DISABILITY - ITS UTILITY IN INTERNATIONAL COMPARISONS

Objectives. The Groningen Activity Restriction Scale (GARS) is a non-d isease-specific instrument to measure disability in activities of dail y living (ADL) and instrumental activities of daily living (IADL). It was developed in studies of Dutch samples consisting of elderly or chr onically ill people. The psychometric properties of the GARS demonstra ted in these studies were highly satisfactory. This paper addresses th e psychometric properties of the GARS across countries. Methods. Data of 623 patients with recently diagnosed rheumatoid arthritis from four European countries were analyzed by means of a principal components a nalysis and a Mokken scale analysis for polychotomous items. Results. The results of the analyses were highly satisfactory; there was one st rong and reliable general factor representing one underlying dimension of disability in ADL and IADL, and there was a clear hierarchical ord ering of the items included in the GARS. The validity of the GARS was strongly suggested by the pattern of associations of the GARS with age , sex, and other existing health status measures. Conclusions. The psy chometric characteristics of the GARS, which measures disability in AD L and IADL simultaneously, make this instrument very useful for compar ative research across countries.