Patterns of missing data in the use of the endometriosis symptom diary

Background Endometriosis is a common, chronic condition in women of reproductive age that is characterized by the presence of functional endometriotic lesions outside the uterus. The Endometriosis Symptom Diary (ESD) is an electronic patient-reported outcome (ePRO) instrument that assesses women’s experience of endometriosis symptoms, with pain scored using a 0–10 numeric rating scale. This study investigated patterns of data missing from the ESD in the VALEPRO study.