Methods for developing and validating outcome measures in paediatric rheumatology.

Developing and validating patient-reported outcome measures (PROMs) requires a specific methodology to ensure that these tools reliably capture patients' subjective experiences of health without clinician bias, thereby supporting their use in patient-centred care for children with chronic diseases. The aim of this article is to review this methodology, emphasising its advantages, and identify unmet needs and priorities for future research in this area. It also introduces the COSMIN and OMERACT initiatives and related aids, as well as the EULAR OML, all of which are critical for developing and selecting the most adequate PROMs in Paediatric Rheumatology.