REMS versus DXA in older adults: diagnostic concordance for osteoporosis in a geriatric outpatient population

REMS showed moderate concordance with DXA but limited interchangeability in geriatric outpatients. Its high negative predictive value supports its use as a practical first-line screening method, especially in adults ≥ 75 years. Findings highlight REMS' potential in settings where DXA is limited and the need for further validation. PURPOSE: Concordance between dual-energy X-ray absorptiometry (DXA) and radiofrequency echographic multispectrometry (REMS) in older adults is heterogeneous, and their interchangeability at the patient level is uncertain. The objective of this study is to examine correlations, diagnostic agreement, and performance of REMS versus DXA in geriatric outpatients, focusing on individuals aged ≥ 75 years and BMI. METHODS: Cross-sectional study of 148 outpatients (median age 75 [70-79] years, 55.4% women). DXA and REMS were performed at the lumbar spine, total hip, and femoral neck. We calculated Spearman correlations, diagnostic performance of REMS using DXA as reference, categorical agreement (Cohen's kappa), linear regressions, and Bland-Altman plots, stratified by age (< 75/ ≥ 75 years) and BMI. RESULTS: DXA-REMS correlations were moderate overall (ρ 0.52-0.64 for BMD and T-scores) but stronger in participants ≥ 75 years (up to ρ 0.75-0.78 at the total hip, p < 0.001). REMS sensitivity was 46-62%, specificity 72-79%, PPV 0.23-0.40, and NPV 0.82-0.93 for osteoporosis (kappa 0.15-0.27). Bland-Altman analyses showed wide limits of agreement, indicating poor interchangeability at the individual level. In adults ≥ 75 years, REMS yielded lower BMD and more negative T-scores at all sites, whereas DXA did not differ by age group. Low BMI was consistently associated with lower BMD and more negative T-scores. CONCLUSIONS: REMS shows moderate concordance with DXA and limited interchangeability, but its high NPV supports a pragmatic role as a first-line screening tool in geriatric practice, especially in adults ≥ 75 years and when DXA is unavailable.