The COPACNE cohort: protocol of a prospective monocentric study of acne determinants, treatment outcomes, and healthcare trajectories in routine dermatological practice

Acne is a common inflammatory dermatosis with a prolonged and heterogeneous course, potentially leading to scarring, psychosocial burden, and repeated healthcare use. However, most available data derive from cross-sectional studies, randomised controlled trials, or administrative databases, which rarely integrate detailed clinical phenotyping, patient-reported outcomes, exposome-related factors, and routine clinical data within the same longitudinal real-world framework. The COPACNE cohort was designed to address this gap by providing a prospective, multidimensional characterisation of acne in routine clinical practice and by exploring factors associated with severity, scarring, and treatment response. COPACNE is a monocentric prospective observational cohort conducted in the Department of Dermatology of Nantes University Hospital. Patients consulting for acne are eligible regardless of age, acne type, or severity and are followed as part of routine care. Data are collected prospectively using electronic case report forms and include clinical severity and scarring scores, patient-reported outcome measures, environmental and lifestyle factors, therapeutic exposure, and, when performed as part of routine care according to the investigator’s clinical judgement, biological tests and bacteriological swabs for microbiological analysis. By integrating clinical, psychosocial, exposome-related, and routine care data within a single prospective framework, COPACNE is expected to generate evidence complementary to that provided by trials and administrative database studies and to support more personalised and sustainable acne management.