SAN FRANCISCO — A trend toward using one set of parameters to diagnose osteoporosis in both men and women hasn't caught on in the United States, where sex-specific bone density scores are the norm, Eric S. Orwoll, M.D., said at a meeting on osteoporosis sponsored by the University of California, San Francisco.
Yet despite the ease of a gender-blind system and some persuasive data, using a sex-specific method is the way to go, at least until more data accumulate on bone loss and fracture risk in men, suggested Dr. Orwoll, professor of medicine at Oregon Health and Science University, Portland.
The evidence supporting the use of one set of parameters is mounting. Studies in recent years have shown, for example, that the 1-year risk for hip fracture overlaps in men and women with the same hip bone mineral densities. As the density gets lower, the risk for fracture increases at essentially the same rate in both sexes.
Such findings have led some bone experts to suggest that it would be easier and logical for clinicians to use just one reference range for diagnosing osteoporosis instead of using separate T scores for men and women. Bone densitometry machines in the United States currently calculate a sex-specific T score.
The International Osteoporosis Foundation in 2000 noted that the same absolute values of bone density in men and women yield the same absolute risk of vertebral or hip fracture, suggesting that using one threshold for calculating risk makes sense. The data on men are scanty, according to the statement.
Those who favor using one set of parameters usually propose using T scores that report the number of standard deviations between current bone density and the mean peak density of a 30-year-old female.
But the problem with using such a strategy, Dr. Orwoll said, is that only about 3% of older men would be identified as osteoporotic, in comparison with a young female reference population, while 19% of older men would be deemed osteoporotic if their T scores came from reference to young male norms.
About 25%–30% of older men will have a fragility fracture, but if the female reference range were used, only a small percentage of them would be identified as osteoporotic.
“So there's a little bit of incongruity in the application of the International Osteoporosis Foundation recommendations, despite the fact that they're scientifically reasonable,” he said.
Dr. Orwoll encouraged clinicians to keep using the current system of sex-specific T scores from densitometry machines until better, long-term, prospective data on fracture risk in men become available.
He added that it's also critical to include other clinical criteria besides T scores in identifying fracture risk in men.