Background/Purpose: Osteoporosis and vertebral fractures are comorbidities of Axial Spondyloarthritis (axSpA). We evaluated the relationship between disease activity and radiographic damage and bone mineral density (BMD) and vertebral fractures (VF) in patients with axSpA.

Methods: Cross-sectional study of patients with axSpA (ASAS Criteria). Disease activity variables: Bath AS Disease Activity Index (BASDAI), ESR, CRP, ASAS-endorsed disease activity scores (ASDAS). Lumbar spine and hip BMD by dual x-ray absorptiometry (DXA) (187(91%) patients). VF assessed by a semiquantitative method (Genant) in lateral thoracic and lumbar spine X-rays. Risk of fracture was assessed with FRAX tool. Bivariate analysis performed to investigate the associations with the presence of osteoporosis and/or VF. Then, binary and multiple logistic regression models applied. SPSS (v23); p-values significant if < 0.05.

Results: We included 206 patients (62 female and 144 male). Mean values: age 51,7±14,1; BASDAI 3,6±2,2; ASDAS-CRP 2,2±0,95; ASDAS-ESR 2,5±0,99; BASFI 3,3±2,78; mSASSS 20,46±19,14; CRP 4,97±8,97mg/L; ESR 18,2±14,8 mm; 25OHvitD 19,83±9,25 ng/mL. Vitamin D deficiency detected in 85.7% of the patients. Low lumbar BMD was detected in 25,7% (z score) and 28,9% (t score) of the patients and low femoral neck BMD in 45,2% (z score) and 59,7% (t score). Lumbar osteoporosis was present in 3,2%/6.9% and hip osteoporosis in 9,1%/13,4% (applying z/t scores respectively). VF were detected in 34% of the patients. Bivariate analysis: ESR, ASDAS-ESR, age, male sex, low 25OHvitD and radiographic damage(mSASSS) were associated to low BMD. Multivariate models confirmed an association between disease activity (ASDAS-ESR) [OR 3.32 (IC 2.35–4.55) p=0.016] and 25OHvitD [OR 0.95 (IC95 0.86–0.98) p=0.029] and low hip BMD(z score). Differences between patients with and without fractures shown in table 1. Multivariate models confirmed the association between CRP [OR2.34 (IC95 1.10-4.98) p=0.027], radiographic damage [mSASS lumbar OR 1.06 (IC95 1.03-1.10) p=0.001], high lumbar BMD [OR 296 (IC95 5.07-12258)p=0.006] and low hip BMD (femoral neck t score) [OR 0.11 (IC95 0.03-0.12)p=0.000] and VF.

Conclusion: In patients with axSpA, low BMD is associated with disease activity and low 25OHvitD. The presence of vertebral fractures is associated with CRP and low hip BMD (p=0.001). Radiographic damage “falsely” increases lumbar BMD results but is associated with the presence of fractures.

Table 1. Significative differences between patients without fractures versus patientes with vertebral fractures

None: Has no relevant financial relationship to disclose

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/osteoporosis-and-vertebral-fractures-are-associated-with-disease-activity-low-vitamin-d-levels-and-spinal-radiographic-damage-in-patients-with-axial-spondyloarthritis/