TORONTO (EGMN) – Women aged 67 years or older with a bone mineral density T score higher than -1.50 on dual energy x-ray absorptiometry can have their next DXA examination deferred for at least 10 years with a low risk that they’ll progress to osteoporosis in the interim, according to an analysis of data from more than 5,000 U.S. women.

“Fewer than 10% of women with a BMD [bone mineral density] T score of more than -1.50 were estimated to transition to osteoporosis if followed for 15 years,” Dr. Margaret L. Gourlay said at the annual meeting of the American Society for Bone and Mineral Research. For these women, “repeat testing before 10 years is unlikely to show osteoporosis,” she said, and for women with a T score of -1.50 to -1.99, “a 5-year interval could be considered.”

The results provide the first evidence-based guidance available on the appropriate interval for osteoporosis screening in elderly women.

“The value of these results is that we can be less concerned about women with good BMD,” Dr. Gourlay said in an interview. “We don’t need to go on autopilot and screen [all women] every 2 years.” Medicare reimburses for screening women aged 65 years or older with dual energy x-ray absorptiometry (DXA) every 2 years, she noted, and hence U.S. physicians often recommend this screening interval. Earlier this year, however, an updated review of osteoporosis screening by the U.S. Preventive Services Task Force (USPSTF) noted that no evidence existed to support any screening interval (Ann. Intern. Med. 2010;153:99-111).

The results “were a surprise in a good way,” said Dr. Gourlay, a family physician at the University of North Carolina in Chapel Hill. “This is good news for women with good BMD. For women with higher bone density, we’re probably doing some unnecessary testing.”

The new results also showed that the T score exerted the strongest influence on the osteoporosis screening interval, more so than clinical risk factors for fracture. Adjustment for “risk factors did not make too much of a difference, so physicians do not need to make a FRAX calculation” to decide a screening interval, she said. “They can just go by the BMD.”

“With FRAX [the World Health Organization’s Fracture Risk Assessment Tool] you don’t just look at BMD, but primary care physicians can’t stop [in the middle of a patient consultation] to calculate a FRAX score,” Dr. Gourlay said. “When a patient has a BMD result in the good range, the main value of the new results is that we can be less concerned about these women” and the need for rescreening in the near future.

“The importance [of the new findings] is not the absolute time estimates we found; it’s the magnitude of the difference. A 16-year interval [for 10% of women to develop osteoporosis] for women in the top two T score groups, and a 5-year interval [for women with a baseline T score of -1.50 to -1.99] is quite different” from the way most physicians practice today, she said.

She cautioned that the finding needs confirmation from similar analyses using different data sets, and that it remains up to health policy-setting groups, such as the USPSTF, to consider the findings and use them to formulate updated screening recommendations. But, she added, the findings have already influenced her own approach to handling screening intervals. “If I have a patient who missed a test and her prior T score was more than -1.50, I’m not nearly as worried now,” she said.

The analysis used data collected in the Study of Osteoporotic Fractures (SOF), which enrolled women aged 65 years or older in four U.S. cities starting in 1986 and has followed them since then. Dr. Gourlay and her associates focused on 5,036 women in the study who underwent at least two serial BMD measures over a total of 15 years, excluding women with osteoporosis at any hip site at baseline, those with an incident hip fracture, those treated with a bisphosphonate or calcitonin, and women who died or dropped out of the study.

The analysis included 1,275 women who had at least one normal baseline BMD value (a T score of -1.00 or greater) and 4,279 women with at least one T score that identified them as having osteopenia (-1.01 to -2.49). Some women fell into both categories if they underwent at least three DXA examinations starting with at least one normal T score followed by at least one osteopenic score. At baseline, the rate of estrogen use ran 25% in women with a normal T score at baseline and 16% in women with osteopenia – relatively high rates by today’s standards but typical for practice in the 1980s.

During follow-up, full transition to osteoporosis occurred in fewer than 1% of the women with a T score of at least -1.00 at baseline, fewer than 5% of those with a T score of -1.01 to -1.49 at baseline, 22% of women with a score of -1.50 to -1.99 at baseline, and in 65% of women with a baseline T score of -2.00 to -2.49.

After adjustment for the covariates of age and continuous bone mineral density, it took an estimated 16 years for 10% of women with a T score of -1.00 or higher at baseline to transition to osteoporosis. The other three subgroups analyzed underwent covariate adjustment for age, body mass index, current estrogen use, any fracture after age 50, current smoking, and oral glucocorticoid use. After adjustment, the average time for 10% of women to transition to osteoporosis was 15.5 years in women following a T score measure of -1.01 to -1.49, 4.5 years in women with a T score of -1.50 to -1.99, and 1.2 years in women with a T score of -2.00 to -2.49.

An additional analysis stratified women by their age at the baseline DXA examination. Even among women aged 85 years, it took an average of nearly 11 years for 10% to develop osteoporosis following a baseline T score of -1.01 to -1.49.

Dr. Gourlay said that she had no disclosures.

Copyright (c) 2010 Elsevier Global Medical News. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

多伦多(EGMN)——美国骨骼与矿物质研究学会年会上报告的一项涉及5,000多名美国妇女的分析显示，对于双能X线吸收法(DXA)测得骨密度(BMD)T评分＞-1.50的67岁以上妇女，可将其下次DXA检查往后推迟至少10年再进行，在这期间她们进展至骨质疏松的风险较低。

 

本分析采用了来自SOF研究的数据。该研究于1986年开始在美国4个城市招募年龄≥65岁的妇女并对她们进行随访。本分析重点分析该研究中15年内进行至少2次连续BMD测量的5,036名妇女，而排除基线时髋关节骨质疏松的妇女、髋关节骨折的妇女、接受二膦酸盐或降钙素治疗的妇女以及死亡或退出研究的妇女。

 

分析纳入1,275名有至少1个正常基线BMD值(T评分≥-1.00)的妇女和4,279名有至少1个提示骨质减少的T评分(-1.01至 -2.49)的妇女。一些进行至少3次DXA检查、在开始时至少有1个T评分正常、随后至少有1个T评分提示骨质减少的妇女同属于上述2个类别。基线时，雌激素使用率在基线T评分正常的妇女中为25%，在骨质减少的妇女中为16%——从目前标准来看，这些使用率相对较高，但在20世纪80年代的临床实践中则较为常见。

 

随访期间，完全进展至骨质疏松的发生率在基线T评分至少-1.00的妇女中为不足1%，在基线T评分-1.01至-1.49的妇女中为不足5%，在基线T评分-1.50至 -1.99的妇女中为22%，在基线T评分-2.00至-2.49的妇女中为65%。

 

校正年龄和连续骨密度协变量后，基线T评分≥-1.00的妇女约需16年才会有10%进展至骨质疏松。校正协变量(年龄、体重指数、当前雌激素的使用、50岁后的任何骨折、当前吸烟和口服糖皮质激素的使用)后，10%的T评分-1.01至-1.49的妇女进展至骨质疏松所需的平均时间为15.5年，T评分-1.50至-1.99的妇女所需时间为4.5年，T评分-2.00至-2.49的妇女所需时间为1.2年。

 

根据基线DXA检查时的年龄对妇女进行进一步分层分析发现，基线T评分-1.01至-1.49的85岁妇女平均约需11年才会有10%进展至骨质疏松。

 

研究者声明无经济利益冲突。

 

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