Comparison of Bone Densitometry of the Phalanges, Distal Forearm and Axial Skeleton in Early Postmenopausal Women Participating in the EPIC Study

We present baseline bone densitometry from the Early Postmenopausal Interventional Cohort study (EPIC, sponsored by Merck, Sharp & Dohme) for the first time, in which 1609 women from England, Oregon, Hawaii and Denmark are participating to investigate the efficacy of daily oral alendronate to prevent early postmenopausal bone loss. We compared radiographic absorptiometry (RA) of the phalanges for bone mineral density (BMD) measurement with single-energy X-ray absorptiometry (SXA) of the distal forearm, and dual-energy X-ray absorptiometry (DXA) of the lumbar spine, proximal femur and distal forearm. In a random subgroup of 308 women, aged 45-60 years, on average 6 years since menopause (YSM), bone densitometry was measured once at baseline by RA of the phalanges besides the mandatory measurements by DXA. Bone densitometry was furthermore measured by SXA at the Danish site (89 women). Sixty-eight of the women had duplicate measurements performed within 1-3 weeks to evaluate the short-term precision error (CV%). One hundred and one healthy premenopausal women, aged 25-48 years, were recruited at the Danish and Hawaiian sites to establish a reference group. The precision error was 1.5% for RA of the phalanges and in the range 1.0-2.2% for SXA and DXA. BMD by RA correlated with BMD measured by SXA and DXA in the range 0.45 < r < 0.72 (p < 0.001). In conclusion, bone densitometry by RA of the phalanges is highly correlated with bone densitometry by SXA and DXA. RA of the phalanges has a short-term precision error comparable to that of SXA and DXA.