DXA In Patients Research Articles

Diagnosis of osteoporosis in COPD patients: Estimation of the 10-year probability of a major osteoporotic fracture (FRAX), and Dual-energy X-Ray Absorptiometry

The aim of the study was to evaluate various methods of osteoporosis diagnostics (FRAX® and Dual-energy Х-Ray absorptiometry – DXA) and the sequence of their application in the diagnostic algorithm in COPD patients without a history of large bone fractures. Methods. Cross-sectional study of 115 COPD patients without exacerbation (93 men and 22 women, mean age 67.2 ± 7.1 years). The study included clinical examination, FRAX® estimation and comparison of the 10-year probability of a major osteoporotic fracture (MOF) with the Russian intervention threshold, spirometry, DXA of lumbar spine and proximal femur, semi-quantitative radiographic morphometry by Genant. All patients were examined using several methods that are possible in clinical practice: 1) FRAX® without DXA; 2) FRAX® + DXA in patients with intermediate 10-year probability of MOF and recalculation of FRAX® probability including femoral neck bone mineral density (BMD); 3) FRAX® + DXA in patients with intermediate 10-year probability of MOF. Take into account DXA results; 4) DXA without FRAX® ; 5) DXA + recalculation of FRAX ® for individuals with normal BMD or osteopenia. Results. In the whole sample of patients 1 – 5 diagnostic methods revealed 5.1, 7.0, 15.7, 44.3, 45.2% of individuals with osteoporosis, respectively. In men, the methods using FRAX ® (1 – 3) gave unsatisfactory results – the number of patients requiring treatment did not exceed 4.3%, while DXA revealed osteoporosis in 43%. FRAX® + DXA analysis in patients with intermediate 10-year probability of MOF (3 th method) was the best for women. The main independent predictors of low bone mineral density were post-bronchodilator FEV 1 ≤ 30% predicted and/or long-term oral glucocorticoid use. Asymptomatic vertebral fractures were detected in 11 patients. Before the radiographic morphometry, treatment would have been prescribed only 1 patient for the 1th or 2th methods; 5 patients – 3th method and 9 patients using 4th or 5th methods. Conclusion. The use of the Russian FRAX® model in men with COPD revealed a very low percentage of people who need osteoporosis treatment; DXA was the optimal diagnostic method. If it`s not possible to perform DXA in the most COPD patients, it should be prescribed to people with very severe bronchial obstruction and/or taking long-term oral glucocorticoid therapy. Regardless of the BMD parameters, semi-quantitative X-ray morphometry should be performed to diagnose asymptomatic vertebral fractures.

The association between renal function and BMD response to bisphosphonate treatment: Real-world cohort study using linked national registers.

Management of osteoporosis given reduced renal function is one of the largest challenges in the bone clinic. Identify the cut-off for renal function below which there would be no overall BMD benefit associated with bisphosphonate use. Track safety outcomes resulting in hospital encounters. Population-based, observational register-linked study of BMD trajectories in adults from the island of Funen (pop 465,000) as a function of estimated creatinine clearance (CKD-epi), treatment and adherence to oBP. One laboratory performed all the biochemical analyses for the area while all DXA scans were in a central facility. For inclusion, patients were required to have both a DXA scan and an eGFR measurement (CKD-EPI) within 1 year prior to their study index date. Medication Possession Ratio (MPR) was calculated from national data. Out of 6176 incident BP users, 1789 had eGFR and DXA measurements at appropriate timepoints for the planned analysis, while this was the case for 3908 of 29,336 non-users. Users of oBPs exhibited progressively smaller gains in BMD with decreasing renal function. However, for CKD stage 3A and better, the annual change in BMD was significantly more positive than in the non-user group at similar levels of renal function. In non-users, the average annual change in BMD was negative but largely unaffected by renal function down to stage 3B. There were no new cases of acute renal injury, glomerulonephritis or dialysis. The rate of new kidney transplantation was zero in non-users and 0.26 per 1000 PY in the BP user population. Hypocalcaemia encounters did not differ significantly from that seen in non-users. The BMD changes observed in real-world users of oBP in this population based single-clinic are consistent with those observed in the original RCTs of alendronate. We noted a gradual decrease in the absolute gains in BMD in oBP users with decreasing renal function though there was no significant interaction - largely explained by low numbers of treated patients with poor renal function - between CKD stage and adherence driven BMD change. There were no cases of acute renal injury resulting in hospital encounters. More data is needed on the efficacy and safety of bisphosphonates in CKD stage 3B to 5 and prescribers should reconsider the low use of DXA in patients with renal function impairment now that a wider range of treatment options are available.

282. Vertebral Hounsfield unit is a better predictor of pedicle screw loosening than the t-score of DXA in patients with lumbar degenerative diseases

BACKGROUND CONTEXT Pedicle screw loosening is a common complication after pedicle screw fixation in osteoporotic patients. The T-score of DXA is widely used to identify osteoporosis preoperatively, but it can be falsely overestimated because of lumbar degenerative changes. Vertebral Hounsfield unit (HU) has proven to be a better tool for evaluating bone mineral density (BMD) in patients with lumbar degenerative diseases (LDD). PURPOSE To compare the performance of using HU and T-score of DXA to evaluate the risk of pedicle screw loosening. STUDY DESIGN/SETTING This is a retrospective study PATIENT SAMPLE We reviewed 252 patients ≥ 50 years old who underwent posterior lumbar fusion with pedicle screw fixation (1-4 levels of fixation) for LDD. OUTCOME MEASURES Pedicle screw loosening: presence of a radiolucent zone ≥ 1mm thick around the screw in lumbar x-ray at 12 months follow-up. METHODS The DXA criterion for osteoporosis: lowest T-score≤ -2.5. The HU criterion for osteoporosis: L1≤110HU or L2≤100HU or L3≤85HU or L1≤80HU. ROC analysis was used to evaluate the validity of predicting screw loosening RESULTS The screw-loosening rate was 30.6% (77/252). T-score showed no significant difference between the loosening group and non-loosening group (-2.1±1.5 vs -1.7±1.6, P=0.074). The average vertebral HU value of L1-L4 was significantly lower in the loosening group (106.8±34.4 vs 129.8±45.7;P CONCLUSIONS Vertebral HU is a better predictor of pedicle screw loosening than the T-score of DXA among patients aged≥50 years old with LDD. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

AB1082 High-Resolution Peripheral Quantitative CT (HRPQCT) in Ankylosing Spondylitis Reveals Diminished Bone Strength and Volumetric Bmd

BackgroundAnkylosing spondylitis (AS) is associated with high risk of osteoporosis and fractures. Fracture risk is predicted by bone mineral density (BMD), bone microarchitecture and strength.BMD is measured by DXA. However,...

Low rates of bone mineral density measurement in Medicare beneficiaries with prostate cancer initiating androgen deprivation therapy

Men with prostate cancer who undergo androgen deprivation therapy (ADT) are at risk for bone loss and fractures. Our objective was to determine if Medicare beneficiaries with prostate cancer in the state of Texas underwent DXA scans when initiating ADT. We identified men diagnosed with prostate cancer between 2005 and 2007 in the Texas Cancer Registry/Medicare linked database, and who received parenteral ADT or orchiectomy. We identified DXA claims within 1year before or 6months after starting ADT. We examined use of bone conservation agents in the subgroup of patients enrolled in Medicare Part D. Multivariate logistic regression models were used to examine determinants of DXA use. The analysis included 2,290 men (2,262 parenteral ADT, 28 orchiectomy); 197 (8.6%) underwent DXA within 1year before and 6months after starting ADT. Men aged 75years or older were more likely to undergo DXA than men aged 66-74years (OR 1.5; 95% CI 1.1-2.1). Those living in small urban areas were less likely to undergo DXA than those in big areas (OR 0.40; 95% CI 0.19-0.82). Of the 1,060 men enrolled in Medicare part D, 59 (5.6%) received bone conservation agents when starting ADT; 134 (12.6%) either received bone conservation agents or underwent DXA. Fewer than one in ten Medicare beneficiaries with prostate cancer initiating ADT underwent a DXA exam. Variation in utilization was also related to residence area size. Further research is needed to identify whether the use of DXA in patients with prostate cancer receiving ADT will result in fracture prevention.

W1135 High Incidence of Osteoporosis in Patients Over 50 Following Restorative Proctocolectomy Suggests Need for Routine Dxa Screening

Background: The incidence of osteoporosis in IBD patients is 14%. Corticosteroids and age are known risk factors. The current AGA guidelines(1) do not recommend performing DXA in patients following restorative proctocolectomy (RPC) for ulcerative colitis. Some studies have suggested that bone density may increase following RPC, however there are no studies of bone density in patients over 50. We hypothesised that following RPC patients over 50 would be at increased risk since they are likely to have had worse disease and received higher doses of corticosteroids than an average population of UC patients. We sought to establish whether DXA should be routinely performed in this group. Method: All RPC patients over 50 seen in an outpatient clinic from August 2006 to August 2007 underwent a DXA bone scan of the hip and vertebral spine unless recently performed. Osteoporosis and osteopenia were diagnosed according to the WHO definitions. The hospital notes were then reviewed. Results: 18% of all patients screened had osteoporosis present either at the hip or vertebral spine. 44% of all patients had osteopenia. Further details are given in Table 1. Conclusion: The results of this study reveal that osteopenia and osteoporosis in RPC patients over 50 is at least as common as that in the general UC population. We therefore recommend that the standard AGA guidelines for osteoporosis screening should be extended to include RPC patients; the results of this study have important implications for clinical practice. Reference List (1) Bernstein CN et al. AGA technical review on osteoporosis in gastrointestinal diseases. Gastroenterology 2003;124(3):795-841. Table 1.

Body composition evaluation by DXA in patients with HIV-AIDS and controls

Body composition evaluation by DXA in patients with HIV-AIDS and controls

Inactivation of theNa-Cl Co-Transporter(NCC) Gene Is Associated With High BMD Through Both Renal and Bone Mechanisms: Analysis of Patients With Gitelman Syndrome andNccNull Mice

Chronic thiazide treatment is associated with high BMD. We report that patients and mice with null mutations in the thiazide-sensitive NaCl cotransporter (NCC) have higher renal tubular Ca reabsorption, higher BMD, and lower bone remodeling than controls, as well as abnormalities in Ca metabolism, mainly caused by Mg depletion. Chronic thiazide treatment decreases urinary Ca excretion (UVCa) and increases BMD. To understand the underlying mechanisms, Ca and bone metabolism were studied in two models of genetic inactivation of the thiazide-sensitive NaCl cotransporter (NCC): patients with Gitelman syndrome (GS) and Ncc knockout (Ncc(-/-)) mice. Ca metabolism was analyzed in GS patients and Ncc(-/-) mice under conditions of low dietary Ca. BMD was measured by DXA in patients and mice, and bone histomorphometry was analyzed in mice. GS patients had low plasma Mg. They exhibited reduced UVCa, but similar serum Ca and GFR as control subjects, suggesting increased renal Ca reabsorption. Blood PTH was lower despite lower serum ionized Ca, and Mg repletion almost corrected both relative hypoparathyroidism and low UVCa. BMD was significantly increased in GS patients at both lumbar (+7%) and femoral (+16%) sites, and osteocalcin was reduced. In Ncc(-/-) mice, serum Ca and GFR were unchanged, but UVCa was reduced and PTH was elevated; Mg repletion largely corrected both abnormalities. Trabecular and cortical BMD were higher than in Ncc(+/+) mice (+4% and +5%, respectively), and despite elevated PTH, were associated with higher cortical thickness and lower endosteal osteoclastic surface. Higher BMD is observed in GS patients and Ncc(-/-) mice. Relative hypoparathyroidism (human) and bone resistance to PTH (mice), mainly caused by Mg depletion, can explain the low bone remodeling and normal/low serum Ca despite increased renal Ca reabsorption.