Vertebral CT attenuation outperforms standard clinical fracture risk prediction tools in detecting osteoporotic disease in lung cancer screening participants

OBJECTIVES: Compare accuracy of vertebral Hounsfield Unit (VHU) attenuation and FRAX and Garvan Fracture Risk Calculators in identifying low bone mineral density (BMD) and prevalent vertebral compression fractures (VF) in lung cancer screening (LCS) participants. METHODS: Baseline CT scans from a single site of the International Lung Screen Trial were analysed. BMD was measured using VHU (of the most caudally imaged vertebra) and quantitative CT (QCT) (low BMD defined as <110 HU and <120 mg/cm(3,) respectively). Prevalent VF were classified semi-quantitatively. 10-year FRAX and Garvan fracture risks were calculated using dual energy X-ray absorptiometry (DXA) femoral neck T-score where available. Discrimination was assessed by area under receiver-operating characteristic curves (AUC). RESULTS: 535 LCS participants were included; 41% had low VHU-BMD, 56% had low QCT-BMD and 10% had ≥1 VF with ≥25% vertebral height loss. VHU demonstrated 94% specificity and 70% sensitivity in identifying low QCT-BMD. VHU was superior to fracture risk tools in discriminating low QCT-BMD (AUC: VHU 0.94 vs FRAX 0.67, Garvan 0.64 [p < 0.05]). In 64 participants with recent DXA scans, VHU was superior to FRAX(T-score) and Garvan(T-score) in discriminating low QCT-BMD (AUC: VHU 0.99, FRAX(T-score) 0.71, Garvan(T-score) 0.71 [p < 0.05]). VHU was non-inferior to FRAX(T-score) and Garvan(T-score) in discriminating VF (AUC: VHU 0.65, FRAX(T-score) 0.53, Garvan(T-score) 0.61). CONCLUSIONS: VHU outperforms clinical risk calculators in detecting low BMD and discriminates prevalent VF equally well as risk calculators with T-scores, yet is significantly simpler to perform. ADVANCES IN KNOWLEDGE: VHU measurement could aid osteoporosis assessment in high-risk smokers undergoing LCS.