This study aims to assess the prevalence of comorbidities in adult JIA and the impact of comorbidity on patients' perceived health state.
Self-reported comorbidity was studied in 344 adult JIA patients who have been included in the biologic register JuMBO. The comorbidity prevalence among the patients was compared to an age- and sex-matched reference group from the population. The correlation of comorbidity with clinical and demographic parameters was analysed by linear or logistic regression models.
Sixty two percent of the JIA patients reported at least one comorbidity. Uveitis was the most common comorbid condition (17.7%), followed by allergic rhinitis (14.5%), migraine (8.7%), and atopic dermatitis (8.7%). The prevalence of cardiovascular disorders was 9.9%, which was not higher than that in the population. However, patients with a systemic onset of JIA (soJIA) had a substantially higher rate of cardiovascular diseases of 40.6% (p=0.033). Patients with soJIA also had the highest prevalence (80.0%) and the highest mean number (1.8) of comorbidities. Patients with at least one comorbid condition suffered more often from fatigue and pain, had a lower functional capacity (p<0.001, each), and a lower physical and mental health-related quality of life than those without comorbidities (p<0.001 and p=0.017, respectively). The presence of any comorbidity and the level of disease activity were independent predictors of a lower SF-36 score.
Our results indicate that comorbid conditions have a significant impact on the perceived health state in adult JIA. Among all JIA patients, those with systemic onset carry the highest risk for comorbidities, in particular for cardiovascular disorders.