Patterns of Uptake, Engagement, and Attrition in Randomized Controlled Trials of Digital Interventions for Eating Disorders: A Systematic Review and Meta‐Analysis

OBJECTIVE: This review aimed to quantify rates of uptake (treatment initiation), adherence (program completion), and attrition (study dropout) in randomized trials of digital eating disorder (ED) interventions, and to synthesize engagement reporting practices, their consistency, and associations with clinical outcomes. METHODS: Randomized trials of digital interventions (web, app, computerized, chatbots, etc.) delivered to people with diagnostic, subthreshold, or self-reported EDs were included. Random-effects meta-analyses were conducted to compute absolute rates of uptake, adherence, and attrition, while a narrative synthesis summarized engagement patterns and reporting. RESULTS: Forty-eight trials were included. The weighted mean uptake rate from 44 intervention conditions was 89.7% (95% PI = 67.0-97.0) and the weighted mean adherence rate from 14 intervention conditions was 41.8% (95% PI = 0.9-83.3). These estimates remained similar in a series of sensitivity analyses that adjusted for biases, outliers, and when limiting to specific clinical population groups. The weighted trial attrition rate was 23.3% (95% PI = 0.8-54.4); for intervention arms specificially it was 29.7% (95% PI = 9.7-62.3) and for waitlist arms it was 18.7% (95% PI = 4.6-52.3). Attrition was lower in trials that had human-participant interaction, offered therapeutic guidance, provided monetary reimbursement, tested a web/computer program (compared to a smartphone application), and had a longer follow-up (> 6 weeks). Reporting of engagement was inconsistent and heterogeneous, with nearly 90 different metrics recorded across trials. There was some evidence linking sustained user engagement to greater clinical benefit. CONCLUSION: Findings offer practical benchmarks to inform future trial planning and highlight design elements that could be leveraged to enhance user engagement and retention.