Psychiatric disorders in incident patients with juvenile idiopathic arthritis - a case-control cohort study

Chronic illness, such as juvenile idiopathic arthritis (JIA), appears to have an impact on the mental health of children and adolescents. The aim of this study was to explore the incidence of mental and behavioural disorders according to age at JIA onset and gender in JIA patients compared to a control population.

Information on all incident patients with JIA in 2000-2014 was collected from the nationwide register, maintained by the Social Insurance Institution of Finland. The National Population Registry identified three controls (similar regarding age, sex and residence) for each case. They were followed up together until 31st Dec. 2016. ICD-10 codes of their psychiatric diagnoses (F10-F98) were obtained from the Care Register of the National Institute for Health and Welfare. The data were analysed using generalized linear models.

The cumulative incidence of psychiatric morbidity was higher among the JIA patients than the controls, hazard ratio 1.70 (95% Cl 1.57 to 1.74), p < 0.001. Phobic, anxiety, obsessive-compulsive, stress-related and somatoform disorders (F40-48) and mood (affective) disorders (F30-39) were the most common psychiatric diagnoses in both the JIA patients (10.4 and 8.2%) and the control group (5.4 and 5.1%), respectively. Female patients were more prone to mental and behavioural disorders than males were, and the risk seemed to be higher in patients who developed JIA in early childhood or adolescence.

Patients with JIA are diagnosed with mental and behavioural disorders more often than controls, and the age at onset of JIA could have implications for future mental health.