Traditional approaches to patient-reported outcomes diaries have been largely paper based. However, paper-based approaches have inherent inefficiencies such as an inability to communicate the entries in real time to the healthcare team, issues related to transport and mobility, and no tailored output related to what is entered. Traditional paper-based approaches also lack the ability to prompt users at regular intervals to record data. This lack of prompting may lead to delays in entering symptoms and exercises (diary hoarding). Electronic mobile devices have addressed some of these limitations. However, until recently these electronic devices have not been able to deliver the data in real time, thus limiting the ability of the care team to interact and respond. With the emergence of wireless mobile devices, which provide real-time linkages between the patient and the researchers, these limitations are largely eliminated. Yet, it is unclear (whether diary hoarding still occurs and) whether prompts are effective in reducing hoarding over the course of many months. The purpose of this analysis was to conduct a summative evaluation of 7474 automated prompts sent to participants with chronic obstructive pulmonary disease (n = 19). These participants were provided with mobile devices for logging exercise and symptom data over a 6-month period as part of a clinical trial. We found a marginal association between length in the study and delay in submission of exercise and symptom data in response to electronic prompts. Factors associated with delayed response to the prompts included older age, limited computer skills, and reports of no exercise. We recommend that future investigators who are using mobile devices in their research pay careful attention to usability issues as well as strategies that might keep patients engaged and motivated.