Prevalence and progression of radiographic enthesopathy at hip and pelvis in patients with axial spondyloarthritis based on CT assessment.

Objective: This single‑center, retrospective study aimed to investigate the prevalence and progression of entheseal lesions at the hip and pelvis via computed tomography (CT) and determine the associated factors in patients with axial spondyloarthritis (axSpA).

Methods: AxSpA patients who underwent CT including the pelvis and hip and age-sex-matched controls who underwent CT for genitourinary indications were analyzed. Eight bilateral entheseal sites were evaluated and scored as follows: 0 (no damage), 1 (irregularities and/or erosions), and 2 (enthesophytes). Agreement between readers for CT scoring was excellent (intraclass correlation coefficient, 0.673-1.000). To evaluate the longitudinal changes of radiographic enthesitis, additional CT for any reason after the baseline CT were also scored.

Results: Ninety-one patients (mean age 36.6 ± 13.1 years) and 91 controls were analyzed. Enthesopathy was more frequently observed in the axSpA group (39.6%) compared to that in controls (21.9%) (P = 0.01), with the symphysis pubis (22.0%) most commonly affected. Entheseal scores of the symphysis pubis and greater trochanter were significantly higher in the axSpA group than those in controls. Smoking (OR, 3.653), modified Stoke Ankylosing Spondylitis Spinal Score (OR, 1.186), and use of TNF-alpha blockers (OR, 4.645) were independent factors associated with enthesopathy in axSpA patients. Radiographic progression of entheseal lesions over approximately 2 years was very rare.

Conclusions: Radiographic enthesopathy of the pelvis and hip was prominent in axSpA patients and linked to spinal damage, smoking, and use of TNF-alpha blockers. Key points • Pelvic enthesopathy was more frequent in axSpA patients than in controls (39.6% vs. 21.9%). • The symphysis pubis was the most commonly affected entheseal site in axSpA patients. • Smoking, spinal damage, and TNF-alpha blockers were independent risk factors for enthesopathy • Radiographic progression of pelvic enthesopathy over two years was rare in axSpA patient.