Objectives: Many AS patients report periods of perceived higher disease activity (flares). This pilot study aims to document disease activity patterns reported by AS patients and examine associations with disease-specific health status measures.
Methods: Consecutive AS patients (n = 114) were asked whether they experience flares, and if they experience symptoms of AS between flares. They were shown the Flare Illustration of disease patterns over time and asked to select the pattern that best described their disease (i) since symptom onset and (ii) in the past year. Associations between reported disease pattern and disease activity (Bath AS Disease Activity Index, BASDAI); functional impairment (Bath AS Functional Index, BASFI); AS Quality of Life (ASQoL); Back Pain (Nocturnal and Overall) and demographic features were assessed in a subsample (n = 83) (statistical significance defined at P <or= 0.05).
Results: Since disease onset 108/113 patients (96%) reported flares, and 82/99 (83%) reported symptoms of AS between flares. Flares typically lasted days or weeks. When patients were asked to characterize their disease pattern using the Flare Illustration, patterns with constant symptoms predominated (>70% of patients) and patterns with constant symptoms since onset (vs intermittent symptoms) were associated with worse health status (ASQoL: P = 0.007; BASDAI: P = 0.029; BASFI: P = 0.013, overall back pain: P = 0.025).
Conclusions: Almost all AS patients report flares in disease activity: 70-80% report constant symptoms with single/repeated flares, while 20-30% report flares with no intermittent symptoms. The former is associated with a significantly poorer health status. These findings will be validated in a prospective study.