A comparison between peripheral BMD and central BMD measurements in the prediction of spine fractures in men.

Introduction: Most of the research on osteoporosis has been conducted on women. Few studies have compared central and peripheral densitometry and their association with vertebral fractures in men. The present study was designed to compare peripheral bone mineral density (BMD) measurements with central BMD measurements, and to examine their association with radiographic spine fracture in men.
Methods: We studied 402 community-dwelling men aged 45-92 years (mean: 70 years) from the Rancho Bernardo Study cohort who attended a clinic visit between 1988 and 1992 when BMD measurements of the midshaft radius, ultradistal wrist, lumbar spine, and total hip were obtained, and who returned for lateral X-rays of the thoracic and lumbar spine an average of 4 years later. Logistic regression, T-scores, and quintiles were used to analyze BMD and its association with vertebral fractures.
Results: The prevalence of osteoporosis defined by the National Osteoporosis Foundation criteria (for women) was 14.2% at the spine and 13% at the hip. Because there are no validated definitions of osteoporosis based on the ability to predict fracture risk for peripheral densitometry, the frequency of overlap by bone site was calculated among men in the lowest quintile of each site. Of the 402 men, 82 men (20.3%) had at least two sites with BMD measurements in the lowest quintile. After an average of 4 years, 33 (8.2%) men had at least one radiographic vertebral fracture, and ten (2.5%) men had at least two vertebral fractures. Low BMD at the spine (with and without covariate adjustment) was associated with having one or more vertebral fractures, whether using NOF T-score-defined osteoporosis [Odds ratio (OR): 3.81; confidence interval (CI): 1.52, 9.57] or the lowest quintile versus all others (OR: 2.53; CI: 1.03, 6.19). After age and/or other covariate adjustments, neither BMD at the total hip nor at the peripheral sites was associated with spine fractures using either NOF women-based criteria or male quintiles from this cohort.
Conclusion: Although different men had osteoporosis defined by quintiles at different sites, only low BMD at the spine was associated with vertebral fracture.