Clinical and MRI features associated with remission following biological therapy in axial spondyloarthritis.

OBJECTIVE: To evaluate clinical and MRI features associated with clinical response in patients with axial spondyloarthritis (axSpA) initiating biological therapy. METHODS: Forty-one biologic-naïve axSpA patients underwent baseline sacroiliac joint MRI before starting biological therapy. Clinical, inflammatory markers, disease activity scores, and MRI data (SPARCC score) were collected. Outcomes included clinical responses according to BASDAI and ASDAS. RESULTS: Twenty-two were women (53.7%), with a median age of 40 years (IQR 34-55) and a median disease duration of 96 months (IQR 60-144). A total of 74.4% were HLA-B27 positive and all of them were clinically active, with median BASDAI and ASDAS-CRP scores prior to MRI of 6.4 (IQR 5.30-7.15) and 3.4 (IQR 2.98-4.03), respectively. At 16 weeks, 52.4% achieved BASDAI remission, which was independently associated with higher iliac erosion (OR 1.1, p 0.029). Clinically important ASDAS improvement occurred in 71.4% of patients and was significantly associated with higher baseline CRP (p 0.011). Major ASDAS improvement was linked to higher initial disease activity and iliac erosion scores, though not independently after adjustment. A combined baseline MRI score (bone edema + erosion) was significantly associated with achieving ASDAS inactive disease (AUC 0.74); No MRI or clinical variables retained independent predictive value in adjusted models. CONCLUSION: Higher iliac erosion scores are independently associated with BASDAI remission after biologic therapy in axSpA. A combined MRI inflammation and structural damage score may help predict ASDAS inactive disease. These findings highlight the value of MRI for identifying patients more likely to benefit from biologic therapy intervention. Key Points ∙ Baseline MRI-detected iliac erosions identify patients more likely to achieve BASDAI remission after initiation of biologic therapy in axSpA. ∙ Patients achieving rapid and deep clinical responses show higher baseline MRI scores reflecting both active inflammation (BME) and established structural damage (iliac erosions). ∙ A combined MRI score integrating bone marrow edema and erosions improves prediction of ASDAS inactive disease, supporting the value of assessment of both inflammation and structural damage.