The assessment of disability with the Groningen Activity Restriction Scale. Conceptual framework and psychometric properties

The conceptual framework, psychometric properties, descriptive statistics, and the rules for administration and scoring of the Groningen Activity Restriction Scale (GARS) for assessing disability in the area of ADL (Activities of Daily Living including mobility) as well as IADL (Instrumental Activities of Daily Living) are presented. The results show that the GARS, which can be administered both face-to-face and by mail questionnaire, is an easy to administer, comprehensive, reliable, hierarchical, and valid measure for assessing disability in older people. By integrating previously developed scales measuring different domains of disability (ADL, IADL, and mobility) and the use of a four-category response format, an accurate and detailed measure of disability can be obtained and a broader range of needs of subjects can be described. The GARS manual, including detailed procedures for administration and scoring, encourages unambiguous administration and interpretation which results in more comparable research outcomes.