What can we Learn from an Electronic Health Diary Campaign?: An observational nested study in the Swiss Multiple Sclerosis Registry (Preprint)

BACKGROUND Electronic health diaries hold promise in complementing standardized surveys in prospective health studies but are fraught with numerous methodological challenges. OBJECTIVE To investigate factors associated with response to an electronic health diary campaign in persons with multiple sclerosis, to identify recurrent topics in free text diary entries, and to assess the content validity of structured diary entries regarding current symptoms and medication intake compared with survey collected information. METHODS Data were collected by the Swiss Multiple Sclerosis Registry (SMSR) during a nested electronic health diary campaign and during the SMSR baseline assessment (serving as comparative data). The content of diary free text information was grouped using two descriptive natural language processing methods. The similarity between structured diary and survey collected symptom and medication intake data was examined using the Jaccard index. RESULTS Campaign participants were more often female, not working full-time, had a more advanced gait impairment, and were on average five years older compared to eligible non-participants. Diary free text entries most often contained references to body parts or body functioning (57.7%), work (56.4%), or health (55.8%). A high similarity between diary and survey collected data was observed for health-related quality of life, and stable or slow-changing symptoms such as fatigue or gait disorder – but not for immunomodulatory medication use. CONCLUSIONS Diary campaign participation seemed dependent on time availability and symptom burden, and was enhanced by reminder emails. Electronic health diaries are a meaningful complement to regular structured surveys but should ideally be embedded into promotional activities or tied to concrete research study tasks to enhance regular and long-term participation. CLINICALTRIAL ClinicalTrials.gov NCT02980640