Resorption markers more predictive of fractures. (Compared with BMD Changes).

STOCKHOLM -- Measures of bone resorption are significantly better predictors of bone fracture risk than changes in bone mineral density and provide much earlier information about the effectiveness of therapy, Dr. Pierre Delmas said at the annual European Congress of Rheumatology.

In a study involving nearly 700 women participating in a randomized trial, Dr. Delmas and his colleagues at Hopital Edouard Herriot, Lyon, France, compared the value of measuring bone mineral density (BMD) with that of two bone resorption markers: C-telopeptide of type I collagen (CTX) and N-telopeptide of type I collage (NTX).

Such resorption markers are already routinely measured by U.S. osteoporosis specialists to monitor patient responses to treatment, noted Dr. Nelson Watts, director of the University of Cincinnati Bone Health and Osteoporosis Center. Yet with a lot of markers available, the results of this study help distinguish CTX and NTX from all the others in terms of their clinical utility he noted in an interview.

Trial participants all had at least one vertebral deformity and were treated with calcium supplementation, a vitamin D supplement whenever required, and a placebo or 5 mg of risedronate daily for 3 years.

Second void urine samples were collected at baseline and at 3 and 6 months follow-up, and were analyzed for concentration of each marker.

They found that early changes in CTX and NTX levels accounted for about two-thirds (67% and 66%, respectively) of risedronate's effect in reducing the risk of vertebral fractures over the 3-year period.

By comparison, increases in BMD accounted for only 28% of risedronate's reduction in fracture rates. And that's actually a higher percentage than what's been reported in the past, Dr. Delmas said. In previous studies looking at the ...