Validation of the Charité Mobility assessment (CHARMI) in older adults across a wide range of functional levels - the prospective longitudinal MobiTest cohort study.

BACKGROUND

Comprehensive mobility assessment is crucial in geriatrics, yet existing tools may lack feasibility, or applicability for older adults with varying functional levels. AIMS: We evaluated the construct validity, interrater reliability, responsiveness, and minimal important change (MIC) of the Charité Mobility Index (CHARMI), in older adults.

METHODS

A prospective longitudinal cohort study was conducted with older adults ≥ 70y undergoing rehabilitation in acute care, inpatient or outpatient rehabilitation. CHARMI assessments were performed at admission and discharge and correlated with established mobility measures – the De Morton Mobility Index (DEMMI), Short Physical Performance Battery (SPPB), Timed Up and Go (TUG), and Barthel Index (BI) mobility items. Construct validity and responsiveness were evaluated using a hypothesis-testing approach based on a priori-hypotheses; interrater reliability (IRR) was assessed in a subsample. The MIC was determined in an anchor-based approach via ROC analysis.

RESULTS

93 participants (mean age 82.8y) were included. Evidence for validity was supported by meeting 7 of 8 a priori hypotheses including strong correlations with DEMMI and SPPB and a moderate inverse correlation with TUG. IRR was 0.97 (95% CI: 0,91; 0,99). Evidence for responsiveness was supported by meeting 6 of 8 a priori hypotheses. The MIC was established at 1.5 CHARMI points. DISCUSSION AND

CONCLUSIONS

This study provides evidence supporting the CHARMI as a valid, responsive and reliable outcome measure with a useful MIC, making it a valuable option for tracking mobility in older adults across different settings and timepoints. Further studies should confirm generalizability and evaluate feasibility.