Personal characteristics and the law of attrition in randomized controlled trials of eHealth services for self-care

Objective: Contribute to understanding of determinants of attrition in Randomized Controlled Trials (RCTs) on eHealth services for self-care and to developing a strategy to attend to them. Background RCTs are considered the "gold standard" in empirical research on medical interventions. However, RCTs of eHealth services for selfcare are often faced with Eysenbach's Law of Attrition; that is, the phenomenon of people dropping out of the study early or being unavailable for follow-up studies. Methods: We investigated the effects of personal characteristics on the number of days people partook in a study on the use of an online lifestyle diary with a personal computer assistant. Results: When we a ssessed four s tages of attrition (i.e., First Glimpser, Early Dropout, Late Dropout, Maintainer) among participants aged 21 to 65, personality (i.e., locus of control), cognitive abilities (i.e., vocabulary), and motivation to perform self-care were important determinants of attrition. Conclusions: These data suggest that both future RCT designs and the eHealth services used during the trial should attend to these determinants. These data have particular relevance to the design of RCTs with older adults given the role of personal characteristics that affect technology use amongst older adults (e.g., cognitive abilities and personality). Applications: Establishing and attending to determinates of attrition in RCTs of eHealth.