Miriam E. Tucker

October 29, 2014

WASHINGTON, DC — Osteoporosis screening guidelines from the US Preventive Services Task Force (USPSTF) miss three-quarters of women 50 to 64 years of age with osteoporosis, and are only "slightly better than chance alone" at discriminating between women with and without the condition, a new study has found.

The results, from one of three top-scoring abstracts here at the North American Menopause Society 2014 Annual Meeting, were presented by Xuezhi (Daniel) Jiang, MD, assistant professor of obstetrics and gynecology at the Sidney Kimmel Medical College of Thomas Jefferson University in Philadelphia.

"Routine osteoporosis screening is not recommended for young postmenopausal women. The question is when to start. A dozen medical societies have published guidelines, with more than 30 risk factors. It's not easy for a clinician to follow," Dr Jiang explained during his presentation.

The USPSTF guidelines on osteoporosis screening call for routine screening — most commonly with dual-energy x-ray absorptiometry (DXA) and quantitative ultrasonography — for women 65 years and older and for younger women who have a fracture risk equivalent to a 65-year-old white woman with no additional risk factors but who have a 10-year risk of 9.3% or higher as measured with the FRAX assessment tool.

However, Dr Jiang and colleagues found that only 24% of the women in their study met the USPSTF criteria for osteoporosis screening.

"None of the current osteoporosis screening strategies is optimal," Dr Jiang told Medscape Medical News. "Commonly used screening modalities such as USPSTF and other risk-based strategies do not seem to have the expected predictive performance," he noted. In fact, "USPSTF has the poorest performance."

This study showed what many of us see, said Lila Nachtigall, MD, professor of obstetrics and gynecology and head of the DXA unit at New York University–Langone Medical Center in New York City. "The guidelines don't always make good medical practice," she noted. "It's the under-65-year-old woman you're going to want to treat. If you wait till 65, then they've got broken bones."

Not Much Better Than Chance

Dr Jiang and colleagues recruited 445 postmenopausal women 50 to 64 years of age who presented for DXA screening from January 2007 to March 2009. They were asked about traits assessed with the FRAX tool, including age, weight, height, race, personal and parental history of fracture, steroid use, smoking status, and history of rheumatoid arthritis.

Of the 38 women found to have osteoporosis on DXA, just nine would have been identified with the USPSTF strategy alone. "In other words, 76% were missed by USPSTF," Dr Jiang reported.

Conversely, of the 77 women who met the USPSTF criteria for high risk, 68 (88%) were found to not have osteoporosis on DXA.

The sensitivity of USPSTF was 24%, specificity was 83%, positive-predictive value was 12%, negative-predictive value was 92%, and area under the curve was 0.62, or "just slightly better than chance alone," Dr Jiang said. The number needed to scan to detect one case of osteoporosis was nine.

In contrast, sensitivity for four other screening modalities ranged from 66% for risk-factor-based screening (one or more) to 95% for a body mass index (BMI) below 28 kg/m². For the other two modalities — the Osteoporosis Self-assessment Tool and the Simple Calculated Osteoporosis Risk Estimation — the numbers needed to scan to detect one case were seven and eight, respectively.

Changing the FRAX cutoff from 9.3% to 4.7% improved the sensitivity to 92%, but increased the number needed to scan to detect one case to 10. "It may be time to revisit and redefine this FRAX-based threshold," Dr Jiang said.

Overall, BMI alone, with a cutoff of 28 kg/m², performed best, with a sensitivity of 95%, specificity of 38%, positive-predictive value of 13%, area under the curve of 0.73, and eight scans needed to detect one case. (Dr Jiang presented data on BMI as a potential osteoporosis predictor in a separate presentation at the meeting.)

Who Should Be Screened?

"I believe the best screening approach is yet to be defined," Dr Jiang told Medscape Medical News. "Body mass index greater than 28 kg/m² alone seems to have the highest sensitivity and area under the curve of all modalities, but is still far from ideal."

Dr Nachtigall said she uses a risk-factor-based approach. "Menopause is such a risk factor. Being female, older than 50, and white, particularly, are three risk factors. Automatically I think those people should be screened at menopause to get a baseline, and 2 years later to see what their loss is. That's a guideline I follow. It's much simpler," she told Medscape Medical News.

An audience member said she has been penalized by payers when she screens women younger than 65 years who don't meet the USPSTF criteria.

"I think that's terrible," said Dr Nachtigall. "I think it's one more example of where the guidelines aren't good."

"We are working on updating this topic," Albert Siu, MD, who is vice-chair of the USPSTF, said in a statement. "In our thorough review of the science, we will consider any new evidence on the balance of benefits and harms for osteoporosis screening in women. When we last looked at this topic in 2011, the task force found that the benefits outweighed the harms of screening for osteoporosis in women 65 years and older and in younger women whose fracture risk is equal to or greater than that of a 65-year-old white woman who has no additional risk factors."

Dr Jiang and Dr Nachtigall have disclosed no relevant financial relationships.

North American Menopause Society (NAMS) 2014 Annual Meeting: Abstract S-13. Presented October 16, 2014.

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