Background The ultimate goal of managing Ankylosing Spondylitis (AS) is to improve and maintain the patient's health-related quality of life (HRQoL). To reach this goal, rheumatologists target towards low disease activity, as this is the main modifiable factor. To date, there is insufficient insight into (1) the co-evolution of disease activity and HRQoL, and (2) the heterogeneity in such trajectories among patients.
Objectives To explore the heterogeneous character of AS by identifying different temporal patterns of co-dependence between disease activity and HRQoL over 8 years follow-up.
Methods Data from Outcome in AS International Study (OASIS; n=161) and Groningen Leeuwarden AS (GLAS; n=264) cohorts were used. All patients had an established diagnosis of AS. In GLAS, all patients started a biological. HRQoL and disease activity were measured bi-annually using ASQoL and ASDAS-CRP respectively. Patients were classified into latent groups with individuals following a similar course of disease activity and HRQoL. These trajectories were estimated by Group-Based Trajectory Modelling. Next, the trajectories were profiled by comparing the latent groups with respect to baseline factors with ANOVA and Chi-square test.
Results Five dual trajectories were revealed (Figure): 1. Low impact of AS on patient (13%): stable low ASQoL and ASDAS inactive disease; 2. Moderate impact (24%): stable moderate ASQoL and ASDAS high disease; 3. Improving impact (21%): major improvement in ASQoL and ASDAS; 4. High impact (29%): moderately severe ASQoL with very high but improving ASDAS; 5. Very High Impact (13%): persistently severe ASQoL with high ASDAS. Low impact of AS was mainly characterized by male gender and HLA-B27; improving impact by younger age, short symptom duration, and biological intake; high impact by higher age, long symptom duration, and (bridging) syndesmophytes (Table).
Conclusions We identified five dual trajectories of disease activity and HRQoL, each demonstrating a clear mutual relationship. These trajectories and their profiles provide insight into the heterogeneity of the impact of AS on patients' health and overall functioning.
Disclosure of Interest None declared