Health-Related Digital Engagement and Incident Stroke in Older Adults: Protective Factor or Marker of Socioeconomic Advantage? A Retrospective Cohort Study (Preprint)

BACKGROUND Most studies on internet use and health outcomes among older adults rely on cross-sectional designs and binary exposure measures. It is usually difficult for time to capture multidimensional health-related digital engagement. The high collinearity between digital engagement and socioeconomic factors makes it challenging to disentangle independent effects from marker effects. Currently, longitudinal evidence linking health-related digital engagement to incident stroke remains limited. OBJECTIVE This study aimed to examine the longitudinal association between a composite Health-Related Digital Engagement Index (HDEI) and incident stroke among community-dwelling older adults. Bisides, it sought to quantify the extent to which socioeconomic factors account for this association. METHODS This prospective cohort study used data from the National Health and Aging Trends Study (NHATS), Waves 1-10 (2011-2020). The HDEI (range 0-4) was constructed from 4 health-related internet behaviors at baseline. The primary outcome was incident stroke ascertained by self- or proxy-reported physician diagnosis. Discrete-time hazard models with a complementary log-log link were fitted with 4 nested models progressively adjusting for demographics, socioeconomic factors, chronic disease burden, disability, and social isolation. RESULTS Among 5,384 participants (81.6% HDEI=0; 10.5% HDEI=1; 7.9% HDEI≥2) followed for a median of 5 years (IQR 2-9), 470 incident stroke events occurred. In the unadjusted model, each 1-point HDEI increase was associated with 24% lower stroke risk (hazard ratio [HR] 0.76, 95% CI 0.66-0.88; P