Abstract
Studies on osteoporosis in axial spondyloarthritis (axSpA) have focused on the lumbar segment, and few studies have assessed bone mineral density (BMD) in the hip and femoral neck in these patients. The aim of this study was to evaluate the prevalence of low BMD and osteopenia in the total hip or femoral neck and the factors associated with these conditions in axSpA patients. This was a single-centre, observational, cross-sectional study among consecutive patients with axSpA according to the ASAS criteria from the CASTRO registry. All patients underwent total hip and femoral neck DXA BMD measurements. Low BMD was defined as a Z-score less than −1, and osteopenia was defined as a T-score less than −1. Multivariate logistic and generalised linear regressions were used to evaluate factors independently associated with low BMD and osteopenia in the hip or femoral neck and those associated with variability in BMD, respectively. A total of 117 patients were included, among which 30.8% were female and the mean age was 45 years. A total of 36.0% of patients had low BMD (28.1% in the total hip and 27.4% in the femoral neck), and 56.0% of patients had osteopenia (44.7% in the total hip and 53.8% in the femoral neck). A multivariate logistic regression showed that age, radiographic sacroiliitis and ASAS-HI were independently associated with low BMD in the total hip or femoral neck. Factors that were independently associated with osteopenia were Body Mass Index, disease duration, radiographic sacroiliitis and ASAS-HI. In conclusion, 36% of the patients with axSpA had low BMD in the total hip or femoral neck. A younger age and radiographic sacroiliitis were the most important factors associated with decreased BMD.
Highlights
Spondyloarthritis (SpA) is a heterogeneous group of rheumatic diseases that involve the axial skeleton and peripheral joints [1]
Factors associated with a decrease in bone mineral density (BMD) in these patients are systemic inflammation, which is evaluated by C-reactive protein (CRP) levels or the erythrocyte sedimentation rate [4], and local inflammation, which is diagnosed by bone marrow oedema on magnetic resonance imaging (MRI) of the spine [5]
A univariate generalised linear regression analysis was performed to determine factors associated with the total hip BMD in axial SpA (axSpA) patients (Table 4), and the results showed no significant effect of age, Body Mass Index (BMI), disease duration, HLA B-27, University of Cordoba Ankylosing Spondylitis Metrology Index (UCOASMI), mSASSS or persistent CRP elevation
Summary
Spondyloarthritis (SpA) is a heterogeneous group of rheumatic diseases that involve the axial skeleton and peripheral joints [1]. Axial SpA is characterised by inflammatory back pain, vertebral fusion in some cases and restricted spinal mobility. Bone remodelling is altered in axSpA patients, as inflammation causes osteoproliferation in cortical areas of the vertebrae and the loss of trabecular bone in vertebral bodies. Low bone mass and biomechanical alteration of the spine produce an increased risk of vertebral fractures [4,5]. SpA has been associated with bone loss in the spine and in the hip [6]. Factors associated with a decrease in bone mineral density (BMD) in these patients are systemic inflammation, which is evaluated by C-reactive protein (CRP) levels or the erythrocyte sedimentation rate [4], and local inflammation, which is diagnosed by bone marrow oedema on magnetic resonance imaging (MRI) of the spine [5]. Impaired back mobility and spinal ankylosis have been associated with low BMD [7]
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