Development and Validation of the Mobility in Middle-Age Questionnaire (MMQ).

Abstract

BACKGROUND Mobility decline often begins in midlife and early identification of individuals at risk of accelerated deterioration can enable timely prevention. However, there is no validated self-report instrument that specifically assesses mobility in the middle-aged population. METHODS The Mobility in Middle-Age Questionnaire (MMQ) was developed through a seven-step Delphi process, consisting of 10 experts, involving item selection and content validation in both English and Hebrew, comprising two factors: (1) Current Mobility Ability and (2) One-Year Mobility Change. Psychometric properties were assessed in 610 U.S. and 594 Israeli middle-aged adults. Analyses included internal consistency, test-retest reliability, structural and construct validity (using the 10-item Physical Functioning scale (PF-10) from SF-36), and floor/ceiling effect assessments. A 'Potential Mobility Risk Zone' was defined as the lowest 20% of MMQ scores. RESULTS The MMQ showed excellent internal consistency (Cronbach's α  =  0.94 English; 0.92 Hebrew) and strong test-retest reliability (ICC = 0.89-0.90). Exploratory factor analysis explained 66% of variance; confirmatory factor analysis showed good fit (CFI = 0.99, TLI = 0.99, SRMR = 0.05). Construct validity was supported, with all pre-defined hypotheses confirmed. MMQ showed significantly lower ceiling effects than PF-10 (3.9% vs. 34.5% in U.S.; 0.17% vs. 25.25% in Israel, p < .001, large effect sizes). A score of 50 (20th percentile) was proposed as a preliminary "Potential Mobility Risk" Threshold. CONCLUSIONS The MMQ is a reliable and valid tool for detecting early mobility decline in midlife. Longitudinal studies are needed to confirm its predictive value and responsiveness to change.