BMD, Micro-Architecture Estimation (TBS) and Vertebral Fracture Assessment (VFA) Extracted From a Single DXA Device in Combination With Clinical Risk Factors Improve Significantly the Identification of Women at High Risk of Fracture

Abstract

s 485 Results: At the time of analysis the animals had a blood lead level of 9.16 mg/dl for the lead exposed group and 0.19 mg/dl for the control group. The bone lead levels were 30.9 mg/g and 0.2 mg/g for the exposed and control animals, respectively. These blood and bone values compare well with human levels (CDC safe threshold limit for blood lead levels is 10mg/dl). Our results show statistically significant decreases in BMD and bone quality parameters after a life long exposure to environmentally relevant lead levels (Figure 1). BMD as measured by DXA is decreased by 4.7% in the limbs and by 4.9% in the vertebrae. These results were corroborated with micro CT data indicating a 30% decrease in BV/TV and 23% decrease in Tb Number (Figure 1). Conclusions: The results of our study indicate that lead exposure causes systemic bone loss and a decrease in bone quality in an adult rat model. This effect occurs at lead levels that are considered to be safe by human standards. This study is the first life-long exposure experiment characterizing the effect of environmentally relevant levels of lead on the skeleton of an animal model. Interestingly, in the past, investigators have suggested that heavy metals in bone could interfere with DXA measurements. We noted a smaller percent decrease in the DXA data as compared to the micro CT data. However, we could not attribute this to any artifact in the measurement by the DXA scanner. Figure 1. Left Panel; DXA BMD data from the femur-tibia region of the rat. The white lines identify the region of interest where the measurements were made. Right Panel; Micro CT data of the metaphyseal region of the distal femur. The CT images are of control (H20) and Pb-treated animals. 104 Bone Structure, Quality, Architecture and Humeral head BV/TVmm/mm TB nb1/mm TB thmm TB sp mm Articular area 0,3 1,4 0,3 0,9 Center 0,1 0,6 0,3 1,7 Lesser tuberosity 0,2 1 0,3 1 Greater tuberosity 0,1 0,6 0,3 1,7 Microarchitecture BMD, MICRO-ARCHITECTURE ESTIMATION (TBS) AND VERTEBRAL FRACTURE ASSESSMENT (VFA) EXTRACTED FROM A SINGLE DXA DEVICE IN COMBINATION WITH CLINICAL RISK FACTORS IMPROVE SIGNIFICANTLY THE IDENTIFICATION OF WOMEN AT HIGH RISK OF FRACTURE Olivier Lamy, Bone Center Diseases Marc-Antoine Krieg, Bone Diseases Center; Marie Metzger, Bone Diseases Center; Bereng ere Aubry-Rozier, Bone Diseases Center; Delphine Stoll, Bone Diseases Center; Didier Hans, Bone Diseases Center Lausanne University Hospital Introduction: Osteoporosis (OP) is a systemic skeletal disease characterized by a low bone mineral density (BMD) and a micro-architectural (MA) deterioration. Clinical risk factors (CRF) are often used as a MA approximation. MA is yet evaluable in daily practice by the Trabecular Bone Score (TBS) measure. TBS is a novel grey-level texture measurement reflecting bone micro-architecture based on the use of experimental variograms of 2D projection images. TBS is very simple to obtain, by reanalyzing a lumbar DXA-scan. TBS has proven to have diagnosis and prognosis value, partially independent of CRF and BMD. The aim of the OsteoLaus cohort is to combine in daily practice the CRF and the information given by DXA (BMD, TBS and vertebral fracture assessment (VFA)) to better identify women at high fracture risk. Methods: The OsteoLaus cohort (1400 women 50 to 80 years living in Lausanne, Switzerland) started in 2010. This study is derived from the cohort COLAUS who started in Lausanne in 2003. The main goals of COLAUS is to obtain information on the epidemiology and genetic determinants of cardiovascular risk in 6700 men and women. CRF for OP, bone ultrasound of the heel, lumbar spine and hip BMD, VFA by DXA and MA evaluation by TBS are recorded in OsteoLaus. Preliminary results are reported. Results: We included 631 women: mean age 67.4 6.7 y, BMI 26.1 4.6, mean lumbar spine BMD 0.943 0.168 (T-score -1.4 SD), TBS 1.271 0.103. Journal of Clinical Densitometry: Assessment of Skeletal Health As expected, correlation between BMD and site matched TBS is low (r250.16). Prevalence of VFx grade 2/3, major OP Fx and all OP Fx is 8.4%, 17.0% and 26.0% respectively. Ageand BMI-adjusted ORs (per SD decrease) are 1.8 (1.22.5), 1.6 (1.2-2.1), 1.3 (1.1-1.6) for BMD for the different categories of fractures and 2.0 (1.4-3.0), 1.9 (1.4-2.5), 1.4 (1.1-1.7) for TBS respectively. Only 32 to 37% of women with OP Fx have a BMD ! -2.5 SD or a TBS !1.200. If we combine a BMD ! -2.5 SD or a TBS ! 1.200, 54 to 60% of women with an osteoporotic Fx are identified. Conclusions: As in the already published studies, these preliminary results confirm the partial independence between BMD and TBS. More importantly, a combination of TBS subsequent to BMD increases significantly the identification of women with prevalent OP Fx which would have been miss-classified by BMD alone. For the first time we are able to have complementary information about fracture (VFA), density (BMD), microand macro architecture (TBS & HAS) from a simple, low ionizing radiation and cheap device: DXA. Such complementary information is very useful for the patient in the daily practice and moreover will likely have an impact on cost effectiveness analysis 105 Bone Structure, Quality, Architecture and