From Childhood to Adulthood: Disease Activity Trajectories in Childhood-Onset Systemic Lupus Erythematosus

Objective. No previous study has studied the longitudinal disease course of childhood-onset systemic lupus erythematosus (cSLE). Our objectives are to assess distinguishable differences in disease activity trajectories in cSLE patients, determine baseline factors predictive of disease trajectory membership, and assess if the different disease activity trajectories are associated with different damage trajectories. Methods. This is a retrospective, longitudinal inception cohort of cSLE patients. Patients were followed from diagnosis as children, until they were adults. SLE disease activity was modeled as a latent characteristic, jointly using the Systemic Lupus Erythematosus Disease Activity Index 2000 and prednisone in a Bayesian growth mixture model. Baseline factors were tested for membership prediction of the latent classes of disease trajectories. Differences in damage trajectories by disease activity classes were tested using a mixed model. Results. A total of 473 patients (82% females), with median age at diagnosis of 14.1 years, were studied. We studied 11,992 visits (2,666 patient-years). We identified 5 classes of disease activity trajectories. Baseline major organ involvement, number of American College of Rheumatology criteria, and age at diagnosis predicted memberships into different classes. A higher proportion of Asians was in class 2 compared to class 5. Class 1 was associated with the most accrual of damage, while class 5 was associated with no significant damage accrual, even after 10 years. Conclusion. There are 5 distinct latent classes of disease trajectory in patients with cSLE. Membership within disease trajectories is predicted by baseline clinical and demographic factors. Membership in different disease activity trajectory classes is associated with different damage trajectories.