Latent clinical trajectories in chronic spontaneous urticaria identified via mobile health monitoring

Abstract Background Chronic spontaneous urticaria (CSU) is characterized by recurrent wheals and/or angioedema persisting for more than six weeks. CSU significantly impairs quality of life, with disease burden closely linked to disease activity and disease control. Methods This real-world observational study analysed anonymised data collected from users of the CRUSE® mobile application in Latvia. Patients with at least two weekly observations were included (n = 131). Disease trajectories were identified using latent class mixed models based on patient-reported outcome measures (PROMs) and disease-related clinical characteristics. Associations between disease activity and self-rated overall health were assessed using non-parametric correlation analyses. Results Three distinct disease trajectories were identified: Controlled (61.8%), characterized by low baseline disease activity and persistently low symptom burden over follow-up; Responders (19.8%), showing high initial disease burden followed by substantial clinical improvement; and Persistent-active (18.3%), with ongoing symptom activity and minimal improvement over time. Baseline disease activity (UAS) and patient-reported impact (VAS) were strongly correlated and inversely associated with self-rated overall health (EQ VAS). Changes in symptom activity were associated with changes in self-rated overall health in the Controlled and Responder groups, whereas these associations were weaker and non-significant in the Persistent-active group. Baseline demographic and clinical characteristics did not significantly predict trajectory membership. Conclusion Real-world data from the CRUSE® mobile application revealed three distinct longitudinal CSU disease trajectories with differing symptom burden, disease control patterns, and self-rated overall health outcomes. These trajectories were not predictable from baseline characteristics alone.