Use of DXA-derived 3D-modeling, as implemented by 3D-shaper®, for the assessment of fracture risk in a population-based setting

Introduction 3D-modeling of hip DXA scans has been proposed to partition BMD into cortical surface (csBMD) and trabecular “volumetric” (tvBMD). We assessed in a population-based cohort whether such partitioning contributes to fracture risk assessment compared to aBMD alone. Methods Participants (N = 4908) from the Rotterdam Study comprised 56% women, mean age 67.4 (SD = 10.1) years. Hip DXA scans were analyzed with enCore (GE Lunar) and 3D Shaper software. Pearson partial correlation was calculated between aBMD, csBMD and tvBMD at the total hip, femoral neck and trochanter. Incident fractures were collected from GP or hospital records. During a mean follow-up of 6.8 (SD = 2.5) years, 171 sustained a hip fracture, and 1019 any-type fractures. Fracture risk estimates were determined as hazard ratios (HR) per SD decrease in BMD, from Cox-regression adjusted for multiple confounders. Results High correlation (r= > 0.81; p < .001) was observed between aBMD and the modeled 3D parameters; also, between csBMD and tvBMD (r = 0.85; p < .001 at total hip). Lower aBMD was associated with higher incidence of any-type (HR = 1.60, 95%CI 1.43-1.78) and hip (HR = 2.46, 95%CI 1.90-3.17) fracture; lower csBMD with increased risk of any-type (HR = 1.44, 95%CI 1.30-1.60) and hip (csBMD HR = 1.76, 95%CI 1.39-2.23) fracture, and tvBMD with increased risk of any-type (HR = 1.62, 95%CI 1.45-1.80) and hip fracture (HR = 2.44, 95%CI 1.88-3.15). Inclusion of aBMD in models with tvBMD or csBMD resulted in high multicollinearity and unreliable coefficient parameters (VIF > 5). The effect of csBMD was largely attenuated after inclusion of tvBMD in the same model for both any-type (csBMD HR = 0.96, 95%CI 0.81-1.13; tvBMD HR = 1.67, 95%CI 1.41-1.98) and hip (csBMD HR = 0.83, 95%CI 0.58-1.21, tvBMD HR = 2.82, 95%CI 1.94-4.10) fractures. Similar results were observed at the neck and intertrochanteric regions. Conclusions DXA-derived 3D modeled parameters are highly correlated to aBMD and do not provide additional value for the estimation of fracture risk beyond aBMD alone.