The association between residual disease and the risk of future disease flares in axial spondyloarthritis: A longitudinal study

Objectives: To assess, in patients with axial spondyloarthritis (axSpA), whether the presence of clinically relevant signs or symptoms (‘residual disease’) while in an inactive disease or low disease activity (ID/LDA) state increases the risk of future disease flares.

Methods: Prospective data were used from SpA-Net, a web-based monitoring system for SpA. Residual disease was defined as the presence of ≥1 patient-experienced indicator (fatigue, back pain, and/or physical function NRS ≥4/10) or objective indicator (active peripheral manifestations, active psoriasis, elevated CRP, and/or physician global assessment NRS ≥2/10) of disease, while in ID/LDA (AxSpA Disease Activity Score [ASDAS]<2.1). A flare was defined as an ASDAS increase ≥0.9 and shift from ID/LDA to high disease activity (ASDAS≥2.1). Multivariable logistic and Cox regression analyses investigated the association between residual disease and (time to) subsequent flares within 12 months.

Results: Among 135 patients (mean age 50.1±13.2 years, 53 (39.3%) females), 80 (62.5%) and 60 (60.0%) had patient-experienced and objective residual disease, respectively. Thirty-four patients (25.2%) experienced a flare, after a mean of 190 (SD 97) days. In adjusted analyses, patient-experienced residual disease in those with lower education levels was associated with an increased risk of flares (OR=17.7, 95%CI 2.1-147.5), and a shorter time-to-flare (HR=12.1, 95%CI 1.6-91.9). Objective residual disease was not associated with the occurrence nor time-to-flare.

Conclusion: The majority of axSpA patients in an ID/LDA state have patient-experienced or objective residual disease. Patient-experienced, but not objective, residual disease predicts flares in patients with lower education levels, suggesting prognostic relevance of residual symptoms in axSpA.