Measuring mobile health engagement in cancer care: Development and psychometric validation of the CmHEAQ scale

Mobile health (mHealth) applications show promise in cancer care, but sustained patient engagement remains poorly understood due to a lack of validated measurement instruments. Existing tools fail to capture cancer-specific engagement dimensions and multidimensional engagement patterns. We developed the Cancer Mobile Health Engagement and Adherence Questionnaire (CmHEAQ) through a systematic three-phase methodology. Phase 1 involved literature review and expert consultation, identifying six theoretical domains: Initial Adoption, Consistency, Duration, Dropout/Continuation Intent, Treatment & Symptom Management, and Emotional/Support Use. Phase 2 established content validity through expert panel review (n = 10) and face validity via patient cognitive interviews (n = 10), yielding 24 items across six domains. Phase 3 included pilot testing (n = 46) and confirmatory validation (n = 218) in cancer patients using mHealth applications at a tertiary oncology centre in Mysore, India. Psychometric evaluation employed reliability analysis, exploratory factor analysis (EFA), and confirmatory factor analysis (CFA). The CmHEAQ demonstrated excellent psychometric properties. Content validity was exceptional (Scale-Content Validity Index=0.94). Internal consistency reliability was excellent in both pilot (Cronbach's α=0.970) and validation samples (α=0.973), with domain-specific reliability ranging from 0.782 to 0.898. EFA revealed six factors explaining 69.09 % variance (Kaiser-Meyer-Olkin=0.91); however, empirical analysis revealed that Initial Adoption and Consistency items loaded together on Factor 1. Confirmatory factor analysis of both the theoretical six-factor and empirically-refined five-factor models showed that the five-factor model (combining Initial Adoption and Consistency into "Engagement Initiation & Maintenance") demonstrated superior fit indices (CFI = 0.903, TLI = 0.889, RMSEA = 0.066 [90 % CI: 0.059–0.073]) compared to the six-factor model (CFI = 0.088, RMSEA = 0.200). All factor loadings ranged from 0.67 to 0.81 (mean = 0.72), demonstrating strong convergent validity. The five-factor structure identified three engagement levels: high engagement (61.5 %), moderate engagement (32.6 %), and low engagement (6.0 %). The CmHEAQ represents the first validated, comprehensive instrument specifically designed to assess multidimensional mHealth engagement in cancer populations across five empirically-derived domains: Engagement Initiation & Maintenance, Duration, Dropout/Continuation Intent, Treatment & Symptom Management, and Emotional/Support Use. The scale enables standardised measurement for research and clinical practice. • First validated cancer-specific mHealth engagement scale with 24 items across 6 domains. • Exceptional reliability (Cronbach's α=0.973) and content validity (S-CVI=0.94). • Identifies high, moderate, and low engagement patterns in cancer patients. • Multidimensional assessment captures adoption, consistency, and clinical use. • Enables standardised measurement for mHealth intervention research and practice.