Age-related bone mineral density patterns in a large German clinical DXA cohort: device-specific comparisons with international reference populations

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In a large German clinical DXA cohort, comparisons with international reference populations were strongly device-dependent. iDXA values were consistently lower, whereas Prodigy Pro values showed closer but age- and cohort-dependent agreement. The data should not be interpreted as scanner-independent German normative reference values. PURPOSE: To describe age-related bone mineral density patterns in a German DXA cohort and to compare device-specific femoral neck (FN) and total hip (TH) standardized BMD values with international reference cohorts. METHODS: We retrospectively analyzed data from 6,086 women using GE Lunar iDXA or Prodigy Pro systems. Device-related differences were evaluated separately by age-group and measurement site using absolute and percentage differences, Hedges' g, Welch tests, and multiple comparison adjustment. For external comparisons, FN and TH BMD data for women aged 20-79 years were converted to standardized BMD and compared separately by device with NHANES III, the Irish DXA-HIP study, and the Italian DINS study. Hedges' g with 95% confidence intervals, two-sided Welch tests, and Holm-adjusted p values were calculated from summary statistics. RESULTS: Prodigy Pro BMD values were higher than iDXA across most age groups and measurement sites, with moderate effect sizes in younger and middle-aged women and smaller differences at older ages. In external comparisons, iDXA sBMD was lower than all reference cohorts in all 36 comparisons (age/site/reference), remaining significant after Holm adjustment. Prodigy Pro showed smaller and age-dependent differences, with 18 of 36 comparisons remaining Holm-significant. Across the reference cohorts, Prodigy Pro percentage differences ranged from -8.9% to 1.3%, whereas iDXA ranged from -19.0% to -1.8%. CONCLUSION: Comparisons with international reference cohorts were strongly dependent on the DXA device. The present clinical cohort should not be interpreted as a scanner-independent German normative reference population. Device-stratified results provide a more appropriate description of concordance with international datasets than pooled analyses.