We studied the rate of remission of lupus nephritis (LN) in an international cohort of 248 children and adolescents with biopsy proven LN. Five different definitions from scientific studies and the definitions recommended by the American College of Rheumatology and Kidney Disease Improving Global Outcomes (KDIGO) were used.
Anonymized clinical data in patients with biopsy proven LN class ≥ III (International Society of nephrology/Royal Pathology Society-ISN/RPS) diagnosed and treated in the last 10 years in 23 international centers from 10 countries were collected. We compared the rate of patients in complete and partial remission applying the different definitions.
The mean age at diagnosis was 11 years and 4 month and 177 were females.The number of patients in complete and partial remission varied a lot between the different definitions. At 24 months, between 50% and 78.8% of the patients were in full remission as defined by the different criteria. The number of patients in partial remission was low, between 2.3% and 25%. No difference in achieved remission was found between boys and girls or between children and adolescents (P > 0.05). Patients with East Asian ethnicity reached remission more often than other ethnicities (P = 0.03-0.0008). Patients treated in high income countries showed a higher percentage of complete remission at 12 and 24 months (P = 0.002-0.000001).
The rate of children and adolescents with LN achieving remission varied hugely with the definition used. Our results give important information for long awaited treatment studies in children and young people.

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