Analysis of Comorbid Diseases in Children with Juvenile Idiopathic Arthritis and Their Effects on the Disease Process

Purpose: Comorbidities are conditions that exist or occur during an index disease course. Comorbidities may affect the chronic disease process. Juvenile idiopathic arthritis (JIA) is a chronic childhood arthritis of unknown etiology. We aimed to evaluate comorbidities associated with JIA and their effects on the course of the disease. Materials and Methods: We included patients under 18 years of age with JIA in our center between 2005 and 2021. All diseases accompanying JIA and recorded in the medical records were considered as comorbidities. JIA disease activity indexes (JADAS27, JSPADAS), damage index (JADI-A, JADI-E), and health assessment questionnaire index (CHAQ) and JIA treatments were compared according to the presence of comorbidity. Results: Two hundred and four patients were included in the study. The median age was 13(4-17.5) years, and the median follow-up time was 5(2-16) years. Ninety-nine (48.5%) patients had at least one comorbidity. Twenty-four patients had more than one comorbidity. The most common comorbidity was FMF (n=31 (15.2%)), followed by uveitis in 23 (11.3%). JADAS 27, and JSPADAS were indifferent in patients with comorbidity (p=0.55, p=0.63, respectively). JADI-A, JADI-E, and CHAQ scores were similar in the two groups (JADI-A:p=0.45; JADI-E:p=0.11; CHAQ disability:p=0.62; CHAQ discomfort:p=0.61; CHAQ pain:p=0.32). Forty-two (42.4%) patients with comorbidities and 43 (41%) patients without comorbidity used biological drugs (p=0.83). Adalimumab treatment was higher in those with comorbidity (patients with comorbidity:n=22 (22.2%); without comorbidity:n=11 (10.5%); p=0.02). Conclusion: Although comorbidity did not affect disease activity, damage score, and Health Assessment Questionnaire index, the JIA treatment varied according to comorbidity.