Study design and populations
This was a national cross-sectional epidemiological study included all-aged patients with AD who were diagnosed clinically by “Williams diagnostic criteria” in the department of dermatology in respective hospitals from 31/34 provincial administrative divisions in China (Figure S1). Exclusion criteria comprised language or other barriers not able to follow questions and give answers in a face to face interview. The cross-sectional entries of patients were screened. Patients were required to provide written informed consent prior to participation. This research was registered in a publicly accessible database (https://clinicaltrials.gov/, ClinicalTrials.gov Identifier: NCT05316805, Cornerstone) and approved by the ethics committees at country level.