ObjectiveWe aimed to investigate how school well-being (SWB) and academic performance of children with juvenile idiopathic arthritis (JIA) compare to their peers on a national level using the Danish national registers. Further, we investigated the potential influence of socioeconomic status (SES).MethodsA population-wide, register-based, cross-sectional study was performed. We compared the results of children with and without JIA in the Danish National Well-Being Questionnaire (DNWQ), the National Danish School Testing (NDST), and their ninth grade (aged approximately 16 yrs) final school marks in Danish and mathematics. The results were analyzed using adjusted ordinal logistic regression (SWB) and linear regression (tests and marks).ResultsIn separate cohorts, we included a total of 505,340 children answering the DNWQ, 812,461 children with NDST results, and the ninth-grade final marks of 581,804 children. Of these children, 1042, 1541, and 1410, respectively, fulfilled the criteria of JIA. Children with JIA reported SWB comparable to their peers, except for the question "Do you perform well in school?" (odds ratio 0.89, 95% CI 0.81-0.99). In the NDST, the children with JIA in general did just as well as their peers. We found no differences in the ninth-grade final marks in either Danish or mathematics. Stratifying the analyses on SES showed no significant differences in the associations.ConclusionOverall, children with JIA report SWB comparable to that of children without JIA and perform equally well in school as children without JIA.