Neighborhood context shapes physical activity intervention outcomes: a comparison of human vs. virtual advisors

Neighborhood conditions are key social determinants of health (SDOH) that play a critical role in healthy aging. Incorporating contextual measures into behavioral medicine interventions is essential for creating adaptable, equity-focused health solutions. Yet, few physical activity (PA) interventions explicitly evaluate how these factors influence effectiveness. We conducted a secondary analysis of the Computerized Physical Activity Support for Seniors (COMPASS) Trial to examine whether neighborhood context, measured by the California Healthy Places Index (HPI), moderated intervention effects on PA among Latino/a older adults. The COMPASS trial was a single-blind, cluster-randomized non-inferiority trial comparing an interactive virtual advisor (reference arm) with a trained human peer advisor. PA outcomes, including weekly minutes of walking and moderate-to-vigorous physical activity (MVPA), were assessed with the CHAMPS questionnaire at baseline and 12 months. Neighborhood conditions were measured with the HPI, a composite index of 25 indicators across eight domains (e.g., housing, education, transportation) that reflect place-based SDOH. Scores range from 0 to 100, with higher values indicating more health-supportive environments. Mixed-effects ANCOVA models adjusted for baseline PA, age, and gender, with a random intercept for study site, and tested effect modification via interaction terms between intervention arm and HPI. Among 245 Latino/a participants (mean age = 62.3 years; 78.8% female), HPI significantly moderated intervention effects. When modeled continuously, significant interactions were observed for 12-month changes in walking (β = − 2.93; P = .041) and MVPA (β = − 2.54 min/week per HPI point; P = .033). These findings indicated that the human advisor was comparatively more effective in lower-HPI neighborhoods, whereas the virtual advisor produced stronger improvements in higher-HPI neighborhoods. In sensitivity analyses using dichotomized HPI, the interaction was significant for MVPA (β = − 112.9; P = .026) and trended for walking (P = .077). Neighborhood context moderated the relative effectiveness of digital versus human-delivered PA interventions. These findings suggest that tailoring delivery strategies, leveraging digital tools in advantaged areas and peer support in under-resourced neighborhoods, may enhance equity in health promotion for older Latino/a adults by explicitly accounting for neighborhood-level social determinants of health. Clinicaltrials.gov NCT02111213 Registered April 2, 2014 https://clinicaltrials.gov/study/NCT02111213.