Data collection and management
All data were collected in an online survey using self-administered parental questionnaires. All acquired data was fully anonymized and only accessible at an individual level to the participant using an individual code on the Qnome platform (www.qnome.eu) as previously described in detail.11 Clinical follow-up data on PMIS symptoms acquired by their pediatricians were entered in the dataset when participants gave permission for data-linking by providing their individual code for that purpose. That way, anonymization of data on the level of the dataset and study center persisted while individual therapy for the attending pediatrician was still possible.