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Measuring bone density in axial spondyloarthropathy: Time to turn things on their side?
Author(s) -
Fitzgerald Gillian,
Anachebe Tochukwu,
McCarroll Kevin,
O'Shea Finbar
Publication year - 2020
Publication title -
international journal of rheumatic diseases
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.795
H-Index - 41
eISSN - 1756-185X
pISSN - 1756-1841
DOI - 10.1111/1756-185x.13765
Subject(s) - medicine , bone mineral , osteoporosis , radiography , bone density , nuclear medicine , spondyloarthropathy , densitometry , body mass index , radiology , orthodontics , ankylosing spondylitis
Aim Osteoporosis in axial spondyloarthropathy (axSpA) is difficult to accurately diagnose due to osteoproliferation of the spine interfering with conventional (anteroposterior, AP) dual‐energy X‐ray absorptiometry (DXA). This study compares AP and lateral projections of DXA when assessing bone mineral density (BMD) of the spine and investigates the impact of osteoproliferation on AP DXA. Method In this cross‐sectional study, structured standardized assessments collected demographic, clinical, laboratory and radiographic data. DXA assessed BMD of the spine using PA and lateral projections. Hip BMD was assessed in the usual manner. World Health Organization (WHO) criteria assessed prevalence of low BMD. Incorporating lateral DXA in the bone health assessment of axSpA was investigated. SPSS was used for statistical analysis. Results A total of 100 patients had paired AP and lateral DXA studies: 78% were male, mean (SD) age 52 (12) years. BMD of the spine measured by AP projection was significantly higher than BMD measured by lateral projection (mean difference 0.34 g/cm 2 , 95% CI 0.30‐0.37). More patients had low BMD with lateral compared to AP projection (47% vs 16%, P = .01). At the hip, 34% of patients had low BMD. Disease duration, body mass index and radiographic severity independently predicted a difference between AP and lateral measurements of the spine. Conclusion Lateral DXA of the spine is unaffected by osteoproliferation of the spine in axSpA and detects significantly more cases of low BMD than conventional AP DXA. Lateral DXA should be included in BMD assessment of patients with axSpA.