German DXA cohort shows device-dependent differences from international bone density references

A retrospective study in Osteoporosis International examined age-related bone mineral density (BMD) patterns in 6,086 women undergoing routine clinical DXA examinations in Germany. Researchers analyzed baseline scans from GE Lunar iDXA and Prodigy Pro systems separately. For women aged 20–79 years, standardized femoral neck and total hip BMD measurements were compared with NHANES III, the Irish DXA-HIP study, and the Italian DINS study.

Prodigy Pro BMD values were higher than iDXA values across most age groups and measurement sites. In external comparisons, iDXA standardized BMD was lower in all 36 age/site/reference comparisons, with all differences remaining statistically significant after Holm adjustment. For Prodigy Pro, 18 of 36 comparisons remained significant. Percentage differences from international reference cohorts ranged from −19.0% to −1.8% for iDXA and from −8.9% to 1.3% for Prodigy Pro.

The findings support device-stratified rather than pooled interpretation of these clinical data. However, the systems were not formally cross-calibrated: neither the same participants nor a shared phantom were measured on both devices. Daily quality-control records supported stability within each device but could not establish equivalence between them. This retrospective clinical cohort should not be treated as a scanner-independent German normative population, and the study was not designed to replace reference datasets used for clinical T- or Z-score calculation.