AGE-RELATED-CHANGES IN OS CALCIS ULTRASONIC INDEXES - A 2-YEAR PROSPECTIVE-STUDY

We performed repeated ultrasound measurements approximately 2 years ap art (average 23 months +/- 3 months) on the os calcis of 113 healthy p ostmenopausal women recruited from two large prospective cohort studie s named OFELY and EPIDOS. Group A (from OFELY) consisted of 88 women a ged 52-72 (63 +/- 5) years, randomly selected from a large insurance c ompany, and group B (from EPIDOS) consisted of 25 women aged 75-88 (80 +/- 4) years, randomly selected from the voting lists. We obtained br oadband ultrasonic attenuation (BUA) and speed of sound (SOS) measurem ents, as well as the Stiffness index, with a Lunar Achilles ultrasound machine. We performed dual energy X-ray absorptiometry (DXA) measurem ents of femoral neck bone mineral density (neck BMD) with a Hologic QD R 2000 for group A and with a Lunar DPX Plus for group B. The decrease that we observed over 2 years was on average +/- 1 SD: -1.01 +/- 4.6 dB/MHz (p = 0.02) for BUA (which is approximately equal to the long-te rm precision error in vitro), -11.3 +/- 9.2 m/s (p = 0.0001) for SOS ( approximately 5 times the precision error), -3.8 +/- 4.2 %YA (p = 0.00 01) for Stiffness (2.5 times the precision error) and -0.01 +/- 0.03 g /cm(2) (p = 0.0001) for neck BMD (approximately equal to the precision error). In terms of percentage change this represents: -1.0% +/- 4.3% for BUA, -0.8% +/- 0.6% for SOS and -1.85% +/- 4.4% for neck BMD. At the individual level, most SOS and Stiffness values were consistent wi th a decrease, whereas BUA and neck BMD values were spread out above a nd below the zero line of no change. The decreases in SOS and Stiffnes s were significantly larger in the early postmenopause (less than or e qual to 20 years since menopause [YSM]) than in the late postmenopause (>20 YSM). We observed a similar trend for BUA and BMD but this did n ot reach statistical significance. We found a weak but significant cor relation between changes in ultrasound variables and changes in neck B MD. However, the 2-year changes observed in SOS were not significantly correlated with changes in BUA. This study suggests that the heel ult rasound measurements of SOS and Stiffness are valuable indices of post menopausal bone loss, and could be used for follow-up in therapeutic t rials.