Navigating the landscape of core outcome set development in dermatology.

The development of core outcome sets (COS), i.e. a minimum set of 'core outcomes' that should be measured and reported in all trials or clinical practice of a specific condition, in dermatology is gathering pace. A total of 44 dermatology-related COS projects have been registered in the online Core Outcome Measures in Effectiveness Trials (COMET) database (https://www.comet-initiative.org/studies/search), and include studies on 26 different skin diseases. With the increasing number of COS in dermatology, care is needed to ensure the delivery of high quality COS that meet quality standards based on state of the art methodology. In 2015, the Cochrane Skin - Core Outcome Set Initiative (CS-COUSIN) was established. CS-COUSIN is an international, multidisciplinary working group, aiming to improve the development and implementation of COS in dermatology. CS-COUSIN has developed guidance on how to develop high quality COS for skin diseases, and supports dermatology-specific COS initiatives. Currently, 16 COS development groups are affiliated to CS-COUSIN following standardized COS development processes. To ensure successful uptake of COS in dermatology, researchers, clinicians, systematic reviewers, guideline developers and other stakeholders should use existing COS in their work.