Age-related differences in clinical and laboratory characteristics of childhood-onset systemic lupus erythematosus: Pre-puberal-onset SLE is prone to delayed diagnosis

Objective: This study aimed to analyze age-specific characteristics of childhood-onset systemic lupus erythematosus (cSLE) at a health center in China.Methods: The children with SLE were grouped based on age at disease-onset: pre-pubertal (<= 7 years), peri-pubertal (8-13 years), and adolescence (14-18 years). The retrospective study included patients with cSLE diagnosed at the Beijing Children's Hospital between 2013 and 2021.Results: A total of 675 females and 178 males were eligible for inclusion in this study. Among them, 160 patients were diagnosed during pre-puberty, 635 during peri-puberty, and 58 during adolescence. The female-to-male ratio of pre-pubertal, peri-pubertal, and adolescent diagnosis was 3.5: 1, 3.6: 1, and 7.28:1, respectively. The median time from onset to diagnosis during the pre-puberal period was 3.0 (IQR 1.0-24.0 months), which was longer than that during the peri-puberal period (1.4; IQR 0.7-4) months and adolescence (1.0; IQR 0.4-2) months (p = <.0001). The proportion of LN in patients diagnosed during the peri-puberal period (304, 46.6%) and during adolescence (27, 47.9%) was higher than that of patients diagnosed during the pre-puberal period (59, 36.9%) (p = .044). 46 (28.8%), 233 (36.7%), and 32 (55.2%) of children diagnosed during the pre-pubertal period, peri-pubertal period, and adolescence, respectively, suffered from leukopenia.Conclusion: The proportion of renal involvement and leukopenia in the pre-pubertal group was lower than that of the pubertal group and adolescent group. More importantly, the younger the age of the patient, the more likely the diagnosis to be delayed.