Disease activity and mental health symptoms in axial spondyloarthritis: concordant or discordant?

Objective We applied latent class and trajectory modelling to examine whether subgroups of axial spondylarthritis (axSpA) patients report discordant scores for disease activity and mental health symptoms at baseline and after treatment change.Methods We analysed axSpA patients from the ASAS Health Index International Validation Study. We applied latent class analysis (LCA) using generalized structural equation modelling to identify subgroups among 1292 individuals, based on baseline Hospital Anxiety and Depression Scale (HADS) subscores and ASDAS. We applied trajectory modelling in a subset (n = 206) requiring treatment change, to identify subgroups of distinct trajectories for HADS and ASDAS over 6 months. All indices were standardized. Baseline characteristics were compared across identified groups.Results For the baseline analysis, three groups were identified with concordant HADS subscores and ASDAS, with similar baseline characteristics except the high HADS/ASDAS group having more peripheral joint involvement and higher CRP levels. Trajectory analysis identified four groups with concordant HADS and ASDAS changes: 54% comparatively low baseline values, 33% medium and, of the high baseline groups, some (7%) had marked improvement (HADS-depression Delta 11, HADS-anxiety Delta 9, ASDAS Delta 2.8), while others (6%) had limited ASDAS improvement (Delta 1.4) with minimal changes in anxiety symptoms (Delta 0.6).Conclusions We did not identify the hypothesized subgroups with discordant disease activity and mental health symptoms. Instead, these domains were closely aligned at baseline and following treatment, suggesting that these symptoms influence each other. Patients with high mental health symptom burden may benefit from knowing that these symptoms often improve alongside disease activity when starting treatment.