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.