Abstract
OBJECTIVE: The Assessment of Burden of Chronic Conditions (ABCC-) tool was developed to provide a comprehensive, holistic evaluation of disease burden on physical, emotional and social level in patients with one or more chronic conditions. This study aimed to assess the validity and reliability of the recently developed module for the ABCC-tool for osteoarthritis (OA). DESIGN: A cross-sectional questionnaire-based study was conducted among patients with hip, knee, hand, wrist, foot and ankle OA. Validity was assessed as (1) the convergent validity with three OA-joint-specific questionnaires measuring pain and stiffness amongst others; (2) the discriminant validity with radiographic Kellgren-Lawrence (KL) scores; and (3) known-groups validity (groups: number of affected joints, and the presence/absence of anxiety, depression, kinesiophobia, and pain catastrophizing). Reliability was assessed as the (1) internal consistency; and (2) test-retest with a two-week interval. RESULTS: 409 OA patients were included. For all joints its convergent validity was according to the hypothesis, i.e. r ≥ 0.7 (hip OA r = -0.73; knee OA r = -0.75; hand and wrist OA r = 0.74; foot and ankle OA r = -0.41). As expected according to the hypothesis, no correlation between burden of OA and KL-scores was found for the discriminant validity. The ABCC-tool was able to distinguish all predefined known-groups (all p < 0.05). The ABCC-tool demonstrated good internal consistency across all domains and joints (total scale in all joints ≥0.87). Test-retest reliability was high (all ICC ≥0.81). CONCLUSION: The ABCC-tool is a valid and reliable tool for assessing the multidimensional burden of OA across different joints.