Examining sociodemographic and health-related characteristics as moderators of an mHealth intervention on physical activity outcomes in young adult cancer survivors.

PURPOSE: This study explored whether sociodemographic and health-related characteristics moderated mHealth PA intervention effects on total and moderate-to-vigorous physical activity (MVPA) at 6 months, relative to a self-help condition among young adult cancer survivors (YACS).

METHODS: We conducted exploratory secondary analyses of data from a randomized controlled trial among 280 YACS. All participants received digital tools; intervention participants also received lessons, adaptive goals, tailored feedback, text messages, and Facebook prompts. Potential moderators were assessed in baseline questionnaires. PA was measured at baseline and 6 months with accelerometers. Linear model repeated measures analyses examined within- and between-group PA changes stratified by levels of potential moderator variables.

RESULTS: Over 6 months, the intervention produced MVPA increases that were ≥ 30 min/week compared with the self-help among participants who were males (28.1 vs. -7.7, p = .0243), identified with racial/ethnic minority groups (35.2 vs. -8.0, p = .0006), had baseline BMI of 25-30 (25.4 vs. -7.2, p = .0034), or stage III/IV cancer diagnosis (26.0 vs. -6.8, p = .0041). Intervention participants who were ages 26-35, college graduates, married/living with a partner, had a solid tumor, or no baseline comorbidities had modest MVPA increases over 6 months compared to the self-help (ps = .0163-.0492). Baseline characteristics did not moderate intervention effects on total PA.

CONCLUSIONS: The mHealth intervention was more effective than a self-help group at improving MVPA among subgroups of YACS defined by characteristics (sex, race, BMI, cancer stage) that may be useful for tailoring PA interventions.

IMPLICATIONS FOR CANCER SURVIVORS: These potential moderators can guide future optimization of PA interventions for YACS.

GOV IDENTIFIER: NCT03569605.