Abstract: 【Abstract】 Objective To investigate factors influencing frequent episodes （≥ 4 episodes within 1 year） in children with moderate-to-severe atopic dermatitis （AD） in China. Methods A national multicenter cross-sectional study was conducted. Patients under the age of 18 years diagnosed with moderate-to-severe AD were enrolled at dermatology clinics in 18 medical institutions across 12 provinces and municipalities in China between June 12 and August 8, 2023. At the time of the visit, their guardians completed a structured questionnaire covering demographic characteristics, clinical features of AD, personal and family history, factors associated with frequent episodes of moderate-to-severe AD, compliance with treatment, and disease awareness. Statistical analyses included t tests, one-way analysis of variance, rank-sum tests, and chi-square tests, with multiple-response analysis applied for multiple-choice questions. Results A total of 965 valid questionnaires were collected, and 965 children with moderate-to-severe AD were included. Among them, there were 531 males and 434 females, 678 （70.3%） were aged 2 - < 12 years, 837 （86.7%） were from urban areas, the age at onset was 2.47 ± 3.03 years, and the median frequency of AD episodes in the past year was 4 times. These children were divided into 2 groups based on the median episode frequency: < 4-episode group （439 cases, 45.5%） and ≥ 4-episode group （526 cases, 54.5%）. Compared with the < 4-episode group, children in the ≥ 4-episode group showed younger ages at onset （2.22 ± 2.98 years vs. 2.76 ± 3.06 years, P = 0.006） and higher proportions of patients with comorbid allergic diseases in both the children themselves （82.9% ［436/526］ vs. 69.7% ［306/439］, χ2 = 23.42, P < 0.001） and their relatives （66.0% ［347/526］ vs. 57.4% ［252/439］, χ2 = 7.46, P = 0.006）. Children in the ≥ 4- episode group also had higher monthly usage of moisturizers （150 ［30, 300］ g vs. 60 ［6, 200］ g） and daily frequency of moisturizer use, greater disease awareness, but more severe fear of medication use （all P < 0.05）. The region and the human development index level were both significantly associated with the episode frequency （both P < 0.001）, with the highest proportion of children from South China in the ≥ 4- episode group （36.3%, 191/526）. Children in the ≥ 4-episode group also had a longer duration of topical glucocorticoid use than those in the < 4-episode group （Z = -2.21, P = 0.027）. External triggers associated with AD episodes mainly included heat exposure （50.36%, 486/965）, hot water bathing （40.73%, 393/965）, seafood （23.52%, 227/965）, and dust mites （33.37%, 322/965）. Conclusion In children with moderate-to-severe AD in China, factors influencing frequent episodes may include residence in southern or economically developed regions, earlier age at onset, having a personal or family history of allergic diseases, and fear of medication use.

Key words: Dermatitis, atopic, Frequent episodes, Influencing factors, Cross-sectional studies, Multicenter study, Surveys and questionnaires