RESUMEN
BACKGROUND: Assessment of treatment effects in clinical trials requires valid information on treatment adherence, adverse events and symptoms. Paper-based diaries are often inconvenient and have limited reliability, particularly for outpatient trials. OBJECTIVES: To investigate the utility of an electronic diary (e-diary) application for patients with skin diseases in outpatient clinical trials. METHODS: An e-diary application was developed and technically validated. Treatment adherence was defined as topical administration by the patient, and patient-reported outcomes, i.e. pain and itch, were evaluated by the e-diary in six clinical trials on newly tested topical drugs. Additionally, the proportion of patients capturing the applied topical drug by camera and filling in the pain and itch scores was defined as e-diary adherence, and patients' perception of usefulness and acceptability of the e-diary were evaluated. RESULTS: Treatment adherence rates of the included 256 patients were high (median 98%, range 97-99%). E-diary adherence was also high with a median of 93% (range 87-97%) for capturing the applied drug by camera, and 89% (range 87-96%) and 94% (range 87-96%) for entering respectively the itch and pain score. Daily symptom scores provided good insights into the disease burden, and patients rated the e-diary as good to excellent with respect to user acceptability. CONCLUSIONS: The results suggest that the e-diary is an excellent way to ensure proper treatment administration, indicated by both the high user acceptability scores and high treatment adherence. Moreover, the e-diary may also be valuable for frequent and reliable monitoring of patient-reported outcomes in daily clinical practice.