From correlation to causation: Evidence-based strategies for promoting IoT adoption among heterogeneous rural elderly...

China's rural elderly face significant healthcare access barriers despite the national Digital Village initiative promoting Internet of Things (IoT) technologies. However, evidence on causal pathways to IoT adoption and cost-effective intervention strategies remains scarce. We surveyed 613 elderly residents (≥60 years) in rural Shanxi using multi-stage random sampling, collecting data on demographics, health status, IoT usage, barriers, and intervention preferences. Beyond descriptive analysis, we employed propensity score matching to identify causal effects, examined heterogeneous treatment responses, and simulated intervention scenarios with cost-effectiveness analysis. Results revealed high chronic disease burden (majority reporting 1-3 conditions) and moderate IoT usage (52.4%) despite low awareness (61.5% with little/no knowledge). Primary barriers were operationalmistouching (51.2%) and interface complexity (45.2%)rather than cost (35.7%). Having a caregiver increased adoption by 21.0 percentage points (95% CI: 8.0-33.0%, p = 0.001), a finding robust across multiple estimation methods (E-value = 4.1), with striking heterogeneity: low-education elderly showed 34.1pp improvement versus 10.1pp for high-education groups. Information-seeking behavior emerged as another modifiable factor (OR=1.25, p=0.02). Scenario-based cost comparison identified health information campaigns as the most efficient strategy, while combined caregiver-information interventions achieved the greatest impact (4.3pp increase). Based on these findings, we developed four evidence-based service modelsSelf-Management, Information-Enhanced, Community-Supported, and Intensive Risk Managementwith a decision pathway matching interventions to user segments. A phased implementation strategy could progressively increase adoption, with greatest gains among vulnerable populations. This study suggests that IoT adoption is fundamentally a social rather than technical challenge, requiring targeted interventions that address heterogeneous needs and optimize resource allocation in resource-constrained rural settings.