On the basis of the findings, published online in JAMA Internal Medicine, the authors recommend against routine repeat testing in postmenopausal women. Other experts, however, caution that the results may not be so broadly generalizable.
For the investigation, Carolyn J. Crandall, MD, of the division of general internal medicine and health services research at the University of California, Los Angeles, and colleagues analyzed data from 7,419 women enrolled in the prospective Women’s Health Initiative study and who underwent baseline and repeat dual-energy x-ray absorptiometry (DXA) between 1993 and 2010. The researchers excluded patients who reported using bisphosphonates, calcitonin, or selective estrogen-receptor modulators, those with a history of major osteoporotic fracture, or those who lacked follow-up visits. The mean body mass index (BMI) of the study population was 28.7 kg/m2, and the mean age was 66.1 years.
The mean follow-up after the repeat BMD test was 9.0 years, during which period 732 (9.9%) of the women experienced a major osteoporotic fracture, and 139 (1.9%) experienced hip fractures.
To determine whether repeat testing improved fracture risk discrimination, the researchers calculated area under the receiver operating characteristic curve (AUROC) for baseline BMD, absolute change in BMD, and the combination of baseline BMD and change in BMD.
With respect to any major osteoporotic fracture risk, the AUROC values for total hip BMD at baseline, change in total hip BMD at 3 years, and the combination of the two, respectively, were 0.61 (95% confidence interval, 0.59-0.63), 0.53 (95% CI, 0.51-0.55), and 0.61 (95% CI, 0.59-0.63). For hip fracture risk, the respective AUROC values were 0.71 (95% CI, 0.67-0.75), 0.61 (95% CI, 0.56-0.65), and 0.73 (95% CI, 0.69-0.77), the authors reported.
Similar results were observed for femoral neck and lumbar spine BMD measurements. The associations between BMD changes and fracture risk were consistent across age, race, ethnicity, BMI, and baseline BMD T-score subgroups.
Although baseline BMD and change in BMD were independently associated with incident fracture, the association was stronger for lower baseline BMD than the 3-year absolute change in BMD, the authors stated.
The findings, which are consistent with those of previous investigations that involved older adults, are notable because of the age range of the population, according to the authors. “To our knowledge, this is the first prospective study that addressed this issue in a study cohort that included younger postmenopausal U.S. women,” they wrote. “Forty-four percent of our study population was younger than 65 years.”
The authors wrote that, given the lack of benefit associated with repeat BMD testing, such tests should no longer be routinely performed. “Our findings further suggest that resources should be devoted to increasing the underuse of baseline BMD testing among women aged [between] 65 and 85 years, one-quarter of whom do not receive an initial BMD test.”
However, some experts are not comfortable with the broad recommendation to skip repeat testing in the general population. “This is a great study, and it gives important information. However, we know, even in the real world, that patients can lose BMD in this time frame and not really fracture. This does not mean that they will not fracture further down the road,” said Pauline Camacho, MD, director of Loyola University Medical Center’s Osteoporosis and Metabolic Bone Disease Center in Chicago,. “The value of doing BMD goes beyond predicting fracture risk. It also helps assess patient compliance and detect the presence of uncorrected secondary causes of osteoporosis that are limiting the response to therapy, including failure to absorb oral bisphosphonates, vitamin D deficiency, or hyperparathyroidism.”
In addition, patients for whom treatment is initiated would want to know whether it’s working. “Seeing the BMD response to therapy is helpful to both clinicians and patients,” Dr. Camacho said in an interview.
Another concern is the study population. “The study was designed to assess the clinical utility of repeating a screening BMD test in a population of low-risk women -- older postmenopausal women with remarkably good BMD on initial testing,” according to E. Michael Lewiecki, MD, vice president of the National Osteoporosis Foundation and director of the New Mexico Clinical Research and Osteoporosis Center in Albuquerque. “Not surprisingly, with what we know about the expected age-related rate of bone loss, there was only a modest decrease in BMD and little clinical utility in repeating DXA in 3 years. However, repeat testing is an important component in the care of many patients seen in clinical practice.”
There are numerous situations in clinical practice in which repeat BMD testing can enhance patient care and potentially improve outcomes, Dr. Lewiecki said in an interview. “Repeating BMD 1-2 years after starting osteoporosis therapy is a useful way to assess response and determine whether the patient is on a pathway to achieving an acceptable level of fracture risk with a strategy called treat to target.”
Additionally, patients starting high-dose glucocorticoids who are at high risk for rapid bone loss may benefit from undergoing baseline BMD testing and having a follow-up test 1 year later or even sooner, he said. Further, for early postmenopausal women, the rate of bone loss may be accelerated and may be faster than age-related bone loss later in life. For this reason, “close monitoring of BMD may be used to determine when a treatment threshold has been crossed and pharmacological therapy is indicated.”
The most important message from this study for clinicians and healthcare policymakers is not the relative value of the repeat BMD testing, Dr. Lewiecki stated. Rather, it is the call to action regarding the underuse of BMD testing. “There is a global crisis in the care of osteoporosis that is characterized by underdiagnosis and undertreatment of patients at risk for fracture. Many patients who could benefit from treatment to reduce fracture risk are not receiving it, resulting in disability and deaths from fractures that might have been prevented. We need more bone density testing in appropriately selected patients to identify high-risk patients and intervene to reduce fracture risk,” he said. “DXA is an inexpensive and highly versatile clinical tool with many applications in clinical practice. When used wisely, it can be extraordinarily useful to identify and monitor high-risk patients, with the goal of reducing the burden of osteoporotic fractures.”
The barriers to performing baseline BMD measurement in this population are poorly understood and not well researched, Dr. Crandall said in an interview. “I expect that they relate to the multiple competing demands on primary care physicians, who are, for example, trying to juggle hypertension, a sprained ankle, diabetes, and complex social situations simultaneously with identifying appropriate candidates for osteoporosis screening and considering numerous other screening guidelines.”
The Women’s Health Initiative is funded by the National Heart, Lung, and Blood Institute; National Institutes of Health; and the Department of Health & Human Services. The study authors reported relationships with multiple companies, including Amgen, Pfizer, Bayer, Mithra, Norton Rose Fulbright, TherapeuticsMD, AbbVie, Radius, and Allergan. Dr. Camacho reported relationships with Amgen and Shire. Dr. Lewiecki reported relationships with Amgen, Radius Health, Alexion, Samsung Bioepis, Sandoz, Mereo, and Bindex.
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