INFLUENCE OF HANDEDNESS ON CALCANEAL ULTRASOUND - IMPLICATIONS FOR ASSESSMENT OF OSTEOPOROSIS AND STUDY DESIGN

Calcaneal ultrasound has been increasingly studied for its potential i n the assessment of osteoporotic fracture risk, The accuracy of such a n assessment is, in part, dependent on the reproducibility of the meas urement. This study examines the impact of handedness on ultrasound me asurements [broadband ultrasound attenuation (BUA) and velocity of sou nd (VOS)] in the calcaneus. Two hundred and sixty-four subjects (57 me n and 297 women) aged 51.1 +/- 13.6 years (mean +/- SD) were studied. For each subject, calcaneal ultrasound measurements were performed on both heels with a McCue CUBA ultrasound densitometer. Right-handed dom inance (94.7%) was determined by structured Interview, Ln men, BUA mea surements were significantly higher on the dominant side: mean differe nce 4.1 +/- 1.5 dB/MHz (mean +/-: SD;p = 0.009), equivalent to 4.2 +/- 1.5% and more than 4 times the average rate of annual change in BUA. The difference between sides was greater in young (<50 years) than old men (>50 years). Among the women, the difference was not statisticall y significant (0.7 +/- 0.9 dB/MHz; p = 0.4); however, it was significa nt in younger women (20-30 years) (99 +/-: 4 vs 90 +/-:4 dB/MHz, p = 0 .01). By contrast VOS did not differ between sides in either men or wo men irrespective of age. Within-subject standard deviation of BUA was 9.8 dB/MHz for men and 8.6 dB/MHz for women and the component due to r ight and left difference was 8.4 dB/MHz for men and 6.9 dB/MHz for wom en, This variability of BUA between right and left heels could increas e the false-positive rate by up to 28% for a cut-off of 2 SD below the mean. These data indicate that variation between left and right heel measurements of BUA is higher than that of random error measurements, particularly in men and younger, presumably more physically active sub jects. Although VOS measurements were not side dependent, in the small er number of studies examining VOS and fracture risk, VOS appears to h ave a weaker predictive power than BUA. Clinical and epidemiological s tudies involving calcaneal BUA measurements should standardize the sid e measured to either the dominant or non-dominant heel, to reduce with in-subject variation and increase their power.