Morning stiffness duration is associated with physician active joint count in juvenile idiopathic arthritis

Background: The aim of this study was to assess whether there is an association between morning stiffness duration and the presence of active arthritis in children with Juvenile Idiopathic Arthritis (JIA). Methods: A single-center retrospective observational study was conducted using data from the Wilhelmina Children’s Hospital. Morning stiffness duration was obtained through Juvenile Arthritis Multidimensional Assessment Report (JAMAR) questionnaires completed by patients around the time of their visit to the paediatric rheumatology clinic. Active arthritis was characterized by using the Active Joint Count (AJC) indicated by the pediatric rheumatologist and was defined as an AJC ≥ 1. Associations between morning stiffness and disease activity were investigated with Kruskal-Wallis and Chi-squared tests. Results: A total of 5421 JAMAR questionnaires from 803 JIA patients who visited the hospital between December 2012 and August 2024 were analysed in this study. A statistically significant association (p < 0.001) was found between morning stiffness duration and the AJC. A diagnostic model with different cut-off values of morning stiffness to predict the presence of active arthritis was constructed, and showed a sensitivity ranging from 0.545 − 0.062 and specificity ranging from 0.755 to 0.990. Conclusion: Our findings show the association between active arthritis and the duration of morning stiffness in JIA patients. The association between morning stiffness and active arthritis could potentially be of value in a multivariate model for monitoring patients remotely and determining whether patients need to be assessed by their physician earlier.