An Electronic Clinical Outcome Assessment (eCOA) is a measure of how a patient feels, functions or survives, collected through an electronic solution. There are four types of eCOA: Electronic Patient-Reported Outcome (ePRO), Electronic Clinician-Reported Outcome (eClinRO), Electronic Performance Outcome (ePerfO), and Electronic Observer-Reported Outcome (eObsRO). Patients participating in a clinical trial use an ePRO solution to complete patient-reported outcome measures and diaries to report their symptoms and experiences. These data are used in the ongoing oversight of patients throughout the clinical trial by the investigators and staff at a clinical site, and often comprises important study endpoints to inform regulatory decision making and medication labelling.