Predictive Value of Severe Symptoms for Residual Disease After Transitioning From High to Low Disease Activity in Axial Spondyloarthritis: A Longitudinal Study

Objective: To investigate whether very high disease activity (VHDA) status or severe symptoms when in HDA state predict residual disease after achieving inactive disease/low disease activity (ID/LDA) in axial spondyloarthritis (axSpA).

Methods: Prospective data from the SpA-Net registry were used. HDA was defined as an Axial Spondyloarthritis Disease Activity Score (ASDAS) ≥ 2.1, and ID/LDA as ASDAS < 2.1. VHDA (predictor 1) was defined as ASDAS > 3.5, and severe symptoms when in HDA state (predictor 2) as a score ≥ 6/10 for fatigue, back pain, and/or physical function. Residual disease (outcome) was defined as presence of ≥ 1 patient-experienced (fatigue, back pain, and/or physical function ≥ 4/10) or objective disease indicator (active peripheral manifestations, active psoriasis, elevated C-reactive protein, or physician global assessment) after achieving ID/LDA. Associations between either predictor and residual disease were investigated using logistic regression.

Results: Overall, 133 patients (58 [43.6%] female, mean age 48.8 [SD 14.5] years) were included. At the HDA timepoint, 16 (12%) patients had VHDA status and 107 (80.5%) experienced severe symptoms. At the ID/ LDA timepoint, prevalence of patient-experienced and objective residual disease was 70.7% (n = 94/133) and 54% (n = 37/68), respectively. VHDA status when in HDA state was not associated with either form of residual disease after achieving ID/LDA. Severe symptoms were associated with patient-experienced residual disease (odds ratio 5.09, 95% CI 1.76-14.71), but not objective residual disease.

Conclusion: Severe symptoms when in HDA state predict patient-experienced, but not objective, residual disease in axSpA, whereas VHDA status does not predict either form. These findings may aid in anticipating residual disease and guiding management.