DEXA Dilemmas: Clarifying Recommendations for Osteoporosis Screening
Taken from the November/December 2017 issue of The Women's Health Activist Newsletter.
We’ve all seen the ads. Pharmaceutical-sponsored commercials and magazine spreads surround us, talking about the “silent killer” — osteoporosis. They warn us that one in two women will break a bone. That you’ll never know you have osteoporosis until you hear a sickening crack. That the only way to prevent this tragedy is to get a bone scan as soon as possible. And oh, by the way, to start taking the medication they’re selling.
Osteoporosis is a condition where bones become weaker and more brittle, but bone loss itself is not painful. Our bones constantly re-model microscopically, peak around age 30, and naturally decline post-menopause. The significant bone loss and weakened bones characterized by osteoporosis are a concern, however, because they increase women’s likelihood of experiencing a fracture, which can cause serious disruption and discomfort. Of all fracture types, vertebral and hip fractures are the most debilitating; vertebral fractures can cause severe pain and deformity, and hip fractures often require surgery and long bedrest recovery.
Preventing fractures is an important goal in women’s health, but osteoporosis’ history complicates this initiative. Our understanding of what the disease is, how to screen for it, and how to treat it has been heavily shaped by Big Pharma’s use of fear-mongering and misleading information to sell as many drugs as possible. Some of these drugs turned out to have rare but serious side effects, a discovery that engendered mistrust among patients. The National Women’s Health Network (NWHN) was instrumental in raising these concerns with the Food and Drug Administration (FDA). We also advocated to change bad practices that led to over-screening and over-treatment. Now, we’re working to undo Big Pharma’s damage, by spreading evidence-based information about screening, medication, and non-medical strategies to strengthen bones and prevent fractures.
DEXA’s Origins
Osteoporosis screening is an important strategy for identifying women who are at risk of fractures. The most common way to screen for weak bones is to assess bone density. Dual-Energy X-Ray Absorptiometry (DEXA) tests scan a woman’s bone density and quantify her risk. The test result is based on statistical standard deviations that compare an individual’s results to healthy young females’ average bone density; if the result is -2.5 or lower (i.e., more negative), the woman is diagnosed with osteoporosis.
One might assume these bone density scanners are used because of evidence from medical research and clinical trials. In fact, that’s not the case. The reason we use DEXA scans comes down to one word: Merck.[1]
In 1995, pharmaceutical giant Merck had just released Fosomax, the first drug in a new category of non-hormonal osteoporosis drugs, called bisphosphontes. But they struggled to sell the drug. Why? Before 1995, women were not diagnosed with osteoporosis until after they had experienced their first fracture. At the time, consumer advocacy groups like the NWHN saw this as a problem, since older women were suffering from preventable fractures. We advocated for greater investment in bone research.[2] But, instead of getting research funded by the National Institutes of Health (NIH), Merck stepped in, looking to expand Fosamax’s market.[1]
Merck wanted Fosamax to be a “blockbuster” drug (with sales of $1 billion annually).[3] It launched a multi-pronged campaign that had transformative effects on the landscape of osteoporosis. First, Merck identified bone density as an easy-to-measure biomarker of bone health. At the time, DEXA devices were expensive and few clinics had them. Merck wanted every woman to have access to DEXA scans, so it purchased its own medical device company and heavily subsidized production of DEXA machines to lower their cost.
Merck’s market manipulation worked. It permanently reduced the price of DEXA machines, and more clinics purchased them. Merck began running fear-mongering ad campaigns hyping osteoporosis’ dangers and putting DEXA scans at the forefront of women's minds. It heavily advertised to well-meaning doctors that women as young as 50 needed baseline density screening. DEXA scan’s wider availability also paved the way for Merck’s successful lobbying for generous Medicare reimbursements for DEXA scans. Yet, substantial evidence shows that bone density alone is a poor predictor of bone strength.[4] Because the threshold for density-based osteoporosis is low, many women who fail DEXA tests will never fracture. Thus, DEXA scans over-estimate how many women are at risk of fracture.
DEXA scans also introduced an entirely new category of disease called “osteopenia.” Osteopenia is diagnosed if a woman’s bone density results are between -1 and -2.5. The designation was originally intended only for research purposes, but Big Pharma’s fear-mongering led women and doctors alike to view osteopenia as an imminent health risk. Women in their 50s were diagnosed with osteopenia and prescribed bisphosphonate medication for an indefinite time to stop their bone loss. The widespread use of bone density scanning coupled with aggressive treatment practices in the 1990s led to a surge in osteoporosis prescriptions. As many as half of all American women age 50 or older could be "diagnosed" with osteopenia based on DEXA scans' assessment of bone density.[5] Not all of these women are actually at imminent risk of fracture. We now know that women with osteopenia only need bisphosphonate treatment in rare circumstances, and that bisphosphonate treatment for more than five years can result in serious side effects like atypical femur fractures. Fosamax became a blockbuster drug — but at a high cost for women who were treated unnecessarily.
What You Should Know About Bone Density Screening
Although bone density screening is flawed, the NWHN supports evidence-based methods for identifying women who are at-risk of hip and spinal fractures. We have far more data now than we did in the 1990s when Merck launched its plan, and have better ideas about what actually helps identify women at high fracture risk.
Guidelines from the United States Preventative Services Task Force (USPSTF) recommend baseline screening for adults with no risk factors at age 65.[6] For those with other risk factors (like corticosteroid use or family history of osteoporosis), screening may be advisable before 65. Women used to return every two years for preventative bone mineral density DEXA scans, regardless of results. New research shows women with normal results at their baseline DEXA screening can safely wait up to 15 years until the next follow-up screening.[7] Women whose baseline screening shows mild bone loss should return sooner, but the exact timeline depends on bone loss severity. Clinical guidelines from the American College of Physicians recommend that women taking bisphosphonates wait until the end of the five-year course of treatment to get re-scanned, instead of doing so midway through treatment.[8]
During the DEXA hype, test results were the only metric for diagnosing women with osteoporosis and prescribing treatment. Now, research shows that assessing risk factors for fracture, in addition to (or even without) bone density results, is far better than DEXA results alone at accurately predicting who is at-risk of fracture.[9] These risk factors include: family history of fractures, inability to rise from a chair, previous hyperthyroidism, current use of anticonvulsant or benzodiazepines, and caffeine intake above 190 mg per day (see box).
Part of the reason DEXA scanning is so heavily relied upon despite its flaws is because the test quantifies risk, simplifying diagnosis and treatment decisions. Incorporating individual risk factors complicates decisions about whether to treat osteoporosis with drug therapies. Due to this dilemma, several algorithms have been developed to help incorporate other risk factors and produce quantitative benchmarks to predict fracture risk. FRAX™ is one of the most widely used osteoporosis algorithms. A provider records a person’s DEXA score and risk factors, and FRAX™ calculates the person’s statistical probability of fracture within the next decade. Several studies indicate that FRAX™ is a useful tool for making treatment decisions,[10] and the NWHN applauds the shift from an exclusive focus on DEXA results. However, the way FRAX™ reaches its statistical output hasn’t been disclosed to the public. This prevents independent organizations like the NWHN from evaluating the tool’s calculations and determining if DEXA scores are being weighted too heavily.
It is important to know that bone density is merely one of many characteristics of weakened bones. Cell type, shape, and arrangement are just a few examples of other factors that can be used to assess bone strength. Some researchers are investigating other screening techniques to look at these other indications of bone weakness, which could provide a more comprehensive assessment than bone density alone. CT scans have been studied for osteoporosis screening, but high exposure to radiation makes this technique less promising. High-resolution Magnetic Resonance Imaging (MRI) scans show promising results and have been shown to correctly identify women with weak bones that had previously fractured, even women with normal bone density.[11] Currently, the drawbacks of high-resolution MRI lie in high cost and scarce availability. These tests require an experienced radiologist to evaluate the results, making them less convenient than DEXA, which is routinized. At present, these screening techniques are still in the research stage, and are not yet a standard part of osteoporosis screening.
Building Healthy Bones Without Medication
We’ve noticed something peculiar about osteoporosis: the focus is mainly on screening. People don’t talk nearly enough about preventing osteoporosis. So, the NWHN has created a list of steps you can take to keep your bones as heathy as possible.
It is important to ensure your body has the nutrients it needs to build and maintain bone strength. This means getting the daily recommended dose of vitamins and minerals like calcium, Vitamins D and B, and eating a healthy diet high in antioxidant vitamins like Vitamin C and E. Calcium is found in leafy green vegetables and dairy products like milk and yogurt. People who are lactose-intolerant or struggle to consume the daily recommended amount may benefit from taking calcium supplements. Vitamin D comes from sun exposure or through supplements. People who spend little time outside or live in cold climates may find it advisable to take a Vitamin D supplement (10 micrograms daily). To get the 700mg of daily recommended Vitamin B, look for healthy animal products like fish, poultry, eggs, and dairy. Some cereals, rice, and soy milks are also fortified with Vitamin B. The evidence about caffeine’s influence on bone health is not overwhelmingly conclusive, but it’s prudent to drink fewer than four cups daily.[12] Overall, studies indicate it’s better to focus on daily recommended intake of specific nutrients and eating a balanced diet rather than focusing on any specific “trendy” bone-strengthening diet.
Exercise is another way to maintain healthy bones. Studies have shown that exercise — especially weight-bearing regimens like walking, dancing, or running — leads to increased bone density. Tai Chi is one of the best forms of exercise for demonstratively increasing bone density and reducing fracture risk. Exercise also increases strength and balance, which can reduce the risk of falls that lead to fractures.
Where Does This Leave Us?
Despite the troubled history of DEXA scans, the NWHN acknowledges their usefulness under certain conditions. We support the USPSTF guideline recommendation for baseline screening at age 65. We also encourage treatment decisions to be made holistically, considering DEXA results alongside other clinical risk factors. Women whose DEXA results show bone loss but who have no other risk factors can be skeptical about their need for medical treatment. Women who have osteoporotic DEXA scores and other risk factors may want to consider treatment.
You may be wondering what osteoporosis treatments are available and how you can prepare to talk to your doctor about medication treatment. Our next issue will address these concerns in an article outlining key considerations for osteoporosis drug treatment.
Caila Brander, MSc, is a former NWHN Policy Fellow, and a current NWHN member. Her work as a public health researcher has been featured in the international AIDS 2020 and Interest 2020 conferences. Today, Caila informs women’s health policy as Senior Program Associate at Results for Development.
The continued availability of external resources is outside of the NWHN’s control. If the link you are looking for is broken, contact us at nwhn@nwhn.org to request more current citation information.
References
[1] Spiegel A, “How A Bone Disease Grew To Fit The Prescription,” All Things Considered (National Public Radio), December 21, 2009. Online: http://www.npr.org/2009/12/21/121609815/how-a-bone-disease-grew-to-fit-the-prescription.
[2] National Women’s Health Network (NWHN), Osteoporosis, Washington (DC): NWHN, 2015. Online at https://nwhn.org/osteoporosis-2/.
[3] National Women’s Health Network (NWHN), The Truth About Hormone Replacement Therapy, Washington, DC: NWHN, 2002.
[4] Wehrli FW, Saha PK, Gomberg BR, et al. “Role of magnetic resonance for assessing structure and function of trabecular bone,” Top Magn Reson Imaging 2002; 13(5): 335-55.
[5] Looker AC, “Prevalence and trends in low femur bone density among older US adults: NHANES 2005-2006 compared with NHANES III,” J Bone Miner Res. 2010; 25(1):64-71.
[6] United States Preventative Service Task Force (USPSTF), Final Recommendation Statement Osteoporosis: Screening, Rockville (MD): USPSTF, January 2011. Online: https://www.uspreventiveservicestaskforce.org/Page/Document/RecommendationStatementFinal/osteoporosis-screening.
[7] Gourlay ML, Fine JP, Preisser JS, et al., “Bone-Density Testing Interval and Transition to Osteoporosis in Older Women,” N Engl J Med 2012; 366:225-233.
[8] American College of Physicians, “Treatment of Low Bone Density or Osteoporosis to Prevent Fractures in Men and Women: A Clinical Practice Guideline from the American College of Physicians,” Ann Intern Med. 2017; 166(11):818-839.
[9] Cummings SR, Nevitt MC, Browner WS, et al., “Risk factors for Hip Fracture in White Women,” NEJM 1995; 322:767-74.
[10] Kanis JA, Johnell O, Oden A, Johansson H, McCloskey E, “FRAXTM and the Assessment of Fracture Probability in Men and Women from the U.K.,” Osteoporosis Int. 2008; 19(4):385-97.
[11] Chang G, Honig S, Yinxiao Liu Y,et al. “7 Tesla MRI of bone microarchitecture discriminates between women without and with fragility fractures who do not differ by bone mineral density,” J Bone Miner Metab. 2015; 33(3):285-93.
[12] Scottish Intercollegiate Guidelines Network (SIGN), SIGN 142: Management of Osteoporosis and Prevention of Fragility Fractures: A National Clinical Guideline, Edinburgh, Scotland: SIGN, 2015.