ABSTRACT
The objective of this study is to identify the prevalence of vertebral fractures (VFs) and to measure the scanographic bone attenuation coefficient of the first lumbar vertebra (SBAC-L1) based CT-scan, a biomarker of bone fragility in patients with rheumatoid arthritis (RA) and ankylosing spondylitis (AS) and in a control group. This monocentric and retrospective study included patients with RA and AS, based on ACR/EULAR or New-York criteria, respectively. A control group was constituted. All of the patients received a CT-scan. VFs were determined via CT-scans according to the Genant classification, and the SBAC-L1 was measured in Hounsfield units (HU). SBAC-L1 ≤145 HU (fracture threshold) defined patients at risk of VFs. 244 patients were included (105 RA, 83 AS, 56 controls). Of the 4.365 vertebrae studied, 66 osteoporotic VFs were found in 36 patients: 18 (17.1%) RA, 13 (15.7%) AS and 5 (8.9%) controls. The mean SBAC-L1 was 142.2 (±48.4) HU for RA, 142.8 (±48.2) for AS, both of which were significantly lower than that of the control group (161.8 (±42.7) HU). Of the 36 patients with VFs and rheumatism, 28% had a T-score ≤-2.5 SD and 71.4% a SBAC-L1 ≤145 HU. A T-score ≤-2.5 SD and a SBAC-L1 ≤145 HU were associated with VF (OR = 3.07 (CI 95%: 1.07; 8.81), and 2.31 (CI 95%: 1.06; 5.06)), respectively. The SBAC-L1 was significantly lower in the RA and AS groups than in the control group. Furthermore, SBAC-L1 ≤145 HU was associated with a higher risk of VFs, with an odds ratio similar to that of a DXA.
Subject(s)
Arthritis, Rheumatoid/diagnostic imaging , Lumbar Vertebrae/diagnostic imaging , Spondylitis, Ankylosing/diagnostic imaging , Absorptiometry, Photon , Aged , Arthritis, Rheumatoid/physiopathology , Bone Density , Bone and Bones/diagnostic imaging , Female , Humans , Male , Middle Aged , New York , Osteoporosis/diagnostic imaging , Osteoporotic Fractures/diagnostic imaging , Prevalence , Radiography/methods , Retrospective Studies , Spinal Fractures/epidemiology , Spine/diagnostic imaging , Spondylitis, Ankylosing/physiopathology , Tomography, X-Ray Computed/methodsABSTRACT
To study vertebral fracture (VF) prevalence and the scanographic bone attenuation coefficient of the first lumbar vertebra (SBAC-L1) on computed tomography scans (CT-scans) in systemic sclerosis patients. This monocentric retrospective study included patients followed from 2000 to 2014 and fulfilling ACR/EULAR 2013 criteria for systemic sclerosis and who underwent a thoracic or thoraco-abdomino-pelvic CT-scan during their follow-up. Clinical characteristics for sclerosis and osteoporosis risk factors were collected. For CT-scan, the VFs were determined according to Genant's classification, the SBAC-L1 was measured in Hounsfield Units (HU), and a SBAC-L1 ≤ 145 HU (fracture threshold) defined patients at VF risk. Predictive factors for SBAC-L1 ≤ 145 HU were studied. A total of 70 patients were included [mean age, 62.3 (± 15.6) years, women 88.5%, diffuse sclerosis 22.9% (n = 16)]. On CT-scans, three VFs were detected in three patients (4.3%). The mean SBAC-L1 was 157.26 HU (± 52.1), and 35 patients (50%) presented a SBAC-L1 ≤ 145 HU. In multivariate analysis, only age (especially patients older than 63 years, OR = 1.08, CI 95% 1.04-1.13, p = 0.001) and calcinosis (OR = 6.04, CI 95% 1.27-28.70, p = 0.02) were independently associated with a SBAC-L1 ≤ 145 HU. On a large sample of patients with systemic sclerosis, the VF prevalence on CT-scan was low (4.3%) while 50% of the patients presented a SBAC-L1 ≤ 145 HU. Interestingly, the presence of calcinosis, periarticular calcifications or acro-osteolysis was linked with low SBAC-L1 and should lead to an osteoporosis screening, especially for patients under 63 years old.
