Pam Harrison

September 21, 2016

ATLANTA — A "virtual biopsy" of the distal radius taken with the help of high-resolution peripheral quantitative computed tomography (HRPQCT, Scanco Medical) identifies women at risk for imminent fracture better than bone-mineral density (BMD) at the femoral neck or use of the fracture risk-assessment tool (FRAX), a new prospective study indicates.

"Most studies have looked at long-term risk of fracture, which is important, of course, but women who are most in need of treatment are those who are at imminent fracture risk," Roland Chapurlat, MD, PhD, from the University of Lyon, France, told Medscape Medical News.

"We developed the Structural Fragility Score (SFS) based on cortical porosity and trabecular density, both of which are markers of structural fragility, and we found that the SFS was greater in women who had sustained a previous fracture, and this was also the case for both imminent fracture and all other types of fracture that occurred during the 9-year follow-up."

The research was presented here by Dr Chapurlat during the annual meeting of the American Society of Bone and Mineral Research 2016 Annual Meeting.

Asked by Medscape Medical News to comment on the study, session cochair Bo Abrahamsen, MD, PhD, from the University of Southern Denmark, Odense, suggested that being able to quickly assess a patient's risk of imminent fracture would be a "useful clinical tool, at least insofar as we have medications that work quickly."

Dr Abrahamsen cautioned, however, that the HRPQCT is still largely a research tool and available only in limited numbers of academic centers.

"So this is not a standard piece of equipment. To acquire the image, you need sophisticated equipment that is currently much more expensive than [dual-energy X-ray absorptiometry] DEXA, so access to this test will likely be more limited than it is for plain DEXA," he noted.

Nevertheless, in time "these scans should become cheaper if the equipment is more widely used," he observed.

SFS Identifies More Imminent Fractures in OFELY Study

The Os des Femmes de Lyon (OFELY) study involved 589 postmenopausal women between 42 and 90 years of age. During 9.4 years of follow-up, 135 sustained an incident fracture.

Images were processed blind to fracture status.

Both the femoral neck BMD and FRAX scores — which rely on clinical variables alone to predict a patient's 10-year probability of having a major osteoporotic fracture — were also assessed to compare their ability to capture women at risk for imminent fracture within the first 2 years of follow-up.

As Dr Chapurlat reported, SFS scores were higher among the women who had sustained the 135 documented fractures, compared with nonfracture controls.

But the femoral neck T-score was lower, at a mean of -1.6 among fracture cases compared with a mean of -1.3 for nonfracture controls, while FRAX scores were predictably higher, at a mean of 13.9 for women who had a fracture compared with a mean of 10 for women who did not sustain a fracture (all end points P = .001).

Comparing the ability of the SFS to predict all fractures over the 9.4-year follow-up, Dr Chapurlat and colleagues found that the SFS identified 26% more patients at risk for imminent fracture than either BMD at the femoral neck and the FRAX score.

Further, "90% of patients identified on BMD and FRAX [at risk for any fracture] were also captured by the SFS, although this was associated with a slightly higher false-positive rate," Dr Chapurlat added.

For all imminent fractures, "the SFS identified 31% more patients at risk," and this time, "all patients identified by BMD and FRAX were also captured by the SFS, even though the false-positive rate was again a bit higher than it was for the other two tests," he noted.

Narrowed down to all impending major osteoporotic fractures, the SFS score identified 45% more patients who were at imminent risk of having a major osteoporotic fracture than BMD and FRAX did.

Again, all patients identified at risk for a major osteoporotic fracture by BMD and FRAX were also captured by SFS, as Dr Chapurlat observed.

"Assessment of structural deterioration by combining high porosity and low trabecular density (SFS) identifies women at risk for all fractures and all imminent fractures, including major osteoporotic fractures over 9 years of follow-up, and it performed better than either femoral neck BMD or FRAX," Dr Chapurlat concluded, adding that the software used to assess the images acquired by HRPQCT should be available online sometime next year.

Once images are acquired, "it will only take a few minutes to arrive at the SFS," he added.

Neither Dr Chapurlat nor Dr Abrahamsen had any relevant financial relationships.

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American Society of Bone and Mineral Research 2016 Annual Meeting. September 17, 2016; Atlanta, Georgia. Abstract 1076.

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