Quantitative computed tomography (QCT) can precisely and with high reproducibility measure spine bone mineral density (BMD) using cardiac computed tomography (CT) scans. 1 Standard for diagnosing osteoporosis is a dual-energy X-ray absorptiometry (DXA) scan. 2 Despite DXA being fast and with low radiation, many patients with osteoporosis goes undiagnosed. 3 Objectives: The aim was to characterise the bone mineral density (BMD) status in a group of patients with low to intermediate risk of

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... ry artery disease (CAD). Methods: This study is a retrospective, cross-sectional study analysing prospectively acquired data from the Dan-NiCAD study. Participants were patients with symptoms suggestive of CAD referred for a cardiac CT between 2014-09 and 2016-03. Patient data were collected from interviews. BMD was measured in 3 vertebrae starting from the left main coronary artery using QCT. We used the American college of radiology cut-off values for lumbar spine QCT to categorise patients into very low(<80 mg/cm 3 ), low(80-120 mg/cm 3 ), or normal BMD(>120 mg/cm 3 ). Results: Analyses included 1487 patients. Mean age was 57 years(range 40-80), 52% were women. The total number of patients with very low BMD was 179 (12%) (105 women, 74 men). The majority of patients with very low BMD was not previously diagnosed with osteoporosis(87%) and received no anti-osteoporotic treatment(90%). Compared to patients with normal BMD, individuals with very low BMD had more risk factors for osteoporosis such as higher age(p<0.001), predisposition to osteoporosis(p<0.001), and were more often former smokers(p<0.01). Conclusions: Very low BMD seems present in a significant proportion of men and women, a majority of which were not diagnosed with osteoporosis or receiving anti-osteoporotic medication. Patients with very low BMD had more osteoporotic risk factors compared to patients with normal BMD. Additional screening for osteoporosis can potentially prevent osteoporotic fractures. However, thoracic spine QCT is a new method without diagnostic cut-off values and prospective studies regarding fracture risk prevention are missing.