Digital X-ray radiogrammetry in the study of osteoporotic fractures: Comparison to dual energy X-ray absorptiometry and FRAX

Johan Kälvesten,Li-Yung Lui,Torkel Brismar,Steven Cummings

doi:10.1016/j.bone.2016.02.011

Abstract

Osteoporosis is often underdiagnosed and undertreated. Screening of post-menopausal women for clinical risk factors and/or low bone mineral density (BMD) has been proposed to overcome this. Digital X-ray radiogrammetry (DXR) estimates hand BMD from standard hand X-ray images and have shown to predict fractures and osteoporosis. Recently, digital radiology and the internet have opened up the possibility of conducting automated opportunistic screening with DXR in post-fracture care or in combination with mammography. This study compared the performance of DXR with FRAX® and DXA in discriminating major osteoporotic fracture (MOF) (hip, clinical spine, forearm or shoulder), hip fracture and femoral neck osteoporosis. This prospective cohort study was conducted on 5278 women 65years and older in the Study of Osteoporotic Fractures (SOF) cohort. Baseline hand X-ray images were analyzed and fractures were ascertained during 10years of follow up. Age-adjusted area under receiver operating characteristic curve (AUC) for MOF and hip fracture and for femoral neck osteoporosis (DXA FN BMD T-score ≤−2.5) was used to compare the methods. Sensitivity to femoral neck osteoporosis at equal selection rates was tabulated for FRAX and DXR. DXR-BMD, FRAX (no BMD) and lumbar spine DXA BMD were all similar in fracture discriminative performance with an AUC around 0.65 for MOF and 0.70 for hip fractures for all three methods. As expected femoral neck DXA provided fracture discrimination superior both to other BMD measurements and to FRAX. AUC for selection of patients with femoral neck osteoporosis was higher with DXR-BMD, 0.76 (0.74–0.77), than with FRAX, 0.69 (0.67–0.71), (p<0.0001). In conclusion, DXR-BMD discriminates incident fractures to a similar degree as FRAX and predicts femoral neck osteoporosis to a larger degree than FRAX. DXR shows promise as a method to automatically flag individuals who might benefit from an osteoporosis assessment.

Highlights

Fragility fractures represent a major public health and economic burden in the European Union and United States [1,2]
Compared with the 4426 women in the Study of Osteoporotic Fractures (SOF) cohort excluded from this analysis due to missing data needed for calculation of FRAX model probabilities, central dual energy X-ray absorptiometry (DXA) or DXRBMD, the 5278 women included in the analytical cohort were, on average, slightly younger and less likely to report poor to fair health status (15.3% vs. 18.7%, p
A corresponding table, supplement table 4, with only the subset of the population that had a previous fracture is provided in the online supplement. This prospective study is the first to directly compare the performance of clinical risk factors (FRAX) and automated Digital X-ray radiogrammetry (DXR) in identifying patients with osteoporosis and those at increased risk for fracture. In this population-based cohort of older community-dwelling women, fracture prediction was similar between the two methods, while the DXR method had substantially higher sensitivity than FRAX to discern those with femoral neck osteoporosis

Summary

Introduction

Fragility fractures represent a major public health and economic burden in the European Union and United States [1,2]. The gold standard for selecting those who would benefit from anti-osteoporotic intervention is bone mineral density (BMD) measurement by dual energy X-ray absorptiometry (DXA) of the femoral neck and/or total hip and lumbar spine [5,6]. More accessible and lower cost techniques for identifying individuals who would benefit from anti-osteoporotic intervention or further evaluation by central DXA, if available, might improve patient care [1,8]. Besides central DXA an increased risk for fracture can be identified based on measurements at a variety of peripheral bone sites including heel, radius, metacarpals and phalanges; by a variety of technologies including DXA, quantitative ultrasound, radiographic absorptiometry and radiogrammetry. Performance varies between measurement sites and technology, but the primary disadvantage of all peripheral measurements is a weaker ability to discriminate hip fractures than DXA BMD measured in the femoral neck

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