Adjusting Fracture Probability by Trabecular Bone Score

Calcified Tissue International, Mar 2015

The aim of the present study was to determine the impact of trabecular bone score on the probability of fracture above that provided by the clinical risk factors utilized in FRAX. We performed a retrospective cohort study of 33,352 women aged 40–99 years from the province of Manitoba, Canada, with baseline measurements of lumbar spine trabecular bone score (TBS) and FRAX risk variables. The analysis was cohort-specific rather than based on the Canadian version of FRAX. The associations between trabecular bone score, the FRAX risk factors and the risk of fracture or death were examined using an extension of the Poisson regression model and used to calculate 10-year probabilities of fracture with and without TBS and to derive an algorithm to adjust fracture probability to take account of the independent contribution of TBS to fracture and mortality risk. During a mean follow-up of 4.7 years, 1754 women died and 1639 sustained one or more major osteoporotic fractures excluding hip fracture and 306 women sustained one or more hip fracture. When fully adjusted for FRAX risk variables, TBS remained a statistically significant predictor of major osteoporotic fractures excluding hip fracture (HR/SD 1.18, 95 % CI 1.12–1.24), death (HR/SD 1.20, 95 % CI 1.14–1.26) and hip fracture (HR/SD 1.23, 95 % CI 1.09–1.38). Models adjusting major osteoporotic fracture and hip fracture probability were derived, accounting for age and trabecular bone score with death considered as a competing event. Lumbar spine texture analysis using TBS is a risk factor for osteoporotic fracture and a risk factor for death. The predictive ability of TBS is independent of FRAX clinical risk factors and femoral neck BMD. Adjustment of fracture probability to take account of the independent contribution of TBS to fracture and mortality risk requires validation in independent cohorts.

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Adjusting Fracture Probability by Trabecular Bone Score

Calcif Tissue Int Adjusting Fracture Probability by Trabecular Bone Score Eugene V. McCloskey 0 1 2 3 4 Anders Ode´n 0 1 2 3 4 Nicholas C. Harvey 0 1 2 3 4 William D. Leslie 0 1 2 3 4 Didier Hans 0 1 2 3 4 Helena Johansson 0 1 2 3 4 John A. Kanis 0 1 2 3 4 0 MRC Lifecourse Epidemiology Unit, University of Southampton , Southampton , UK 1 Centre for Metabolic Bone Diseases, University of Sheffield Medical School, University of Sheffield , Beech Hill Road, Sheffield S10 2RX , UK 2 & John A. Kanis 3 Center of Bone Diseases, Lausanne University Hospital , Lausanne , Switzerland 4 University of Manitoba , Winnipeg , Canada The aim of the present study was to determine the impact of trabecular bone score on the probability of fracture above that provided by the clinical risk factors utilized in FRAX. We performed a retrospective cohort study of 33,352 women aged 40-99 years from the province of Manitoba, Canada, with baseline measurements of lumbar spine trabecular bone score (TBS) and FRAX risk variables. The analysis was cohort-specific rather than based on the Canadian version of FRAX. The associations between trabecular bone score, the FRAX risk factors and the risk of fracture or death were examined using an extension of the Poisson regression model and used to calculate 10-year probabilities of fracture with and without TBS and to derive an algorithm to adjust fracture probability to take account of the independent contribution of TBS to fracture and mortality risk. During a mean followup of 4.7 years, 1754 women died and 1639 sustained one or more major osteoporotic fractures excluding hip fracture and 306 women sustained one or more hip fracture. When fully adjusted for FRAX risk variables, TBS remained a statistically significant predictor of major osteoporotic fractures excluding hip fracture (HR/SD 1.18, 95 % CI 1.12-1.24), death (HR/SD 1.20, 95 % CI 1.14-1.26) and Epidemiology; Fracture probability; FRAX; Osteoporosis; Trabecular bone score - hip fracture (HR/SD 1.23, 95 % CI 1.09–1.38). Models adjusting major osteoporotic fracture and hip fracture probability were derived, accounting for age and trabecular bone score with death considered as a competing event. Lumbar spine texture analysis using TBS is a risk factor for osteoporotic fracture and a risk factor for death. The predictive ability of TBS is independent of FRAX clinical risk factors and femoral neck BMD. Adjustment of fracture probability to take account of the independent contribution of TBS to fracture and mortality risk requires validation in independent cohorts. Introduction The measurement of bone mineral density (BMD) by dual X-ray absorptiometry (DXA) remains the cornerstone for the assessment of skeletal strength and fracture risk in the clinical setting [ 1 ]. The wide recognition that BMD has limitations in terms of capturing other skeletal determinants of bone strength (for example, bone structure, geometry, cortical and trabecular architecture, and bone turnover), and has led to many attempts to provide supplementary information to improve the predictive ability of skeletal assessments. Such approaches include indices such as hip axis length, hip structural analysis including buckling ratios, cortical thickness, cortical porosity, and more complex techniques such as finite element analysis [ 2–9 ]. The gain from such developments has been disappointing and none has been incorporated into routine clinical practice. More recently, a novel gray-scale textural analysis of antero-posterior lumbar spine DXA images has produced an index, the trabecular bone score (TBS), that shows promise as a BMD-independent predictor of skeletal strength [10]. TBS appears to be an index of bone microarchitecture that provides skeletal information additional to the standard BMD measurement. Higher values of TBS correlate with better skeletal microstructure. A recent literature review determined that TBS consistently discriminated between fracture cases and non-fracture controls in both cross-sectional and longitudinal studies, and that the discrimination is complementary to BMD derived from the same images [ 10 ]. TBS can therefore be regarded as another potential clinical risk factor for fracture and, as such, its ability to predict fracture independently of other well-established risk factors needs to be determined. Risk factors that are partly independent of both age and BMD have been incorporated into FRAX . FRAX estimates the 10-year probability of hip and major osteoporotic fracture based on the individual’s risk factor profile [ 11, 12 ], and is now the leading risk assessment model used worldwide [13]. The probability of fracture is calculated from age, body mass index (BMI), a number of dichotomised risk variables, and additionally femoral neck BMD. The aim of the present analysis was to determine whether TBS could predict fracture risk independently of the risk factors incorporated in FRAX, and if so, to derive adjustment a (...truncated)


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Eugene V. McCloskey, Anders Odén, Nicholas C. Harvey, William D. Leslie, Didier Hans, Helena Johansson, John A. Kanis. Adjusting Fracture Probability by Trabecular Bone Score, Calcified Tissue International, 2015, pp. 500-509, Volume 96, Issue 6, DOI: 10.1007/s00223-015-9980-x