Incorporating the Bone Health Life Chart into your Practice

Feb 20, 2017

In this article, Dr. Ralph Bovard explores osteopenia and osteoporosis. He also presents a case for creating a BMD Life Chart to track bone mineral density over a patient's lifetime.

 

Scope of Problem

Osteopenia and osteoporosis are recognized as a significant problem in the modern medical arena. Men and women, but especially women, lose bone density and bone strength as they age. This fact is reflected in the increased incidence of fractures in the elderly - most notably hip, wrist and spinal compression fractures. 

It is estimated that approximately 10 million older adults have osteoporosis.1 Some estimates show that half of women will have an osteoporosis-related fracture in her life. One-quarter will develop spinal deformities and nearly 2 million will have a hip fracture.2 Osteoporosis-related fractures are known to be associated with reduced quality of life, chronic pain, disability, loss of independence and shortened lifespan.2 In 2002, the costs of osteoporosis were estimated to be $22 billion in the Medicare population. 3

Medical strategies to avoid fractures most often focus on fall prevention, calcium supplementation, dietary interventions, weight bearing exercises, and, in the past 15-20 years, pharmaceutical treatment with bisphosphonates. Screening and medical treatment options often come too late.4

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The U.S. Preventive Services Task Force (USPSTF) has penned guidelines to evaluate women for osteoporosis.5

At present the USPSTF has recommended bone density screening for women older than 65 years and for women between 60–64 years at increased risk for osteoporotic fractures (B Recommendation). However, they do not have recommendations for screening postmenopausal women less than 60 years old or women between 60–64 years without increased risk. There was insufficient evidence to make screening recommendations for men. 

USPSTF recommends that women obtain a bone scan, utilizing a Dual Energy X-ray Absorptiometry (DEXA) machine, at age 65. DEXA provides a comparative assessment of a patient’s bone density that is reported in two different ways:  T-score which compares bone mineral density (BMD) to a group of 30 year-old inpiduals of the same gender and a Z-score analysis that compares the patient to a group of age-controlled peers.  

The World Health Organization (WHO) developed bone mineral density criteria in 1992 to describe the normal skeletal baseline in a healthy 30-year-old white female reference population.6 BMD measures in grams per cm2 (g/cm2). The BMD score is assessed based on a standard deviation (SD) from the expected average value or mean. If the score shows that the bone density is greater than the mean value or less than one standard deviation below the mean (ie -1.0 to +2.5 SD), the inpidual is considered to be in the normal range. If the BMD is between one and 2.5 standard deviations below the mean (-1.0 SD to -2.5 SD), then the inpidual is considered to be osteopenic. If the BMD is greater than 2.5 standard deviations below the mean (>-2.5 SD) then the inpidual is considered osteoporotic. The FRAX (fracture risk assessment algorithm) tool developed by WHO incorporates BMD measured by DEXA to predict the probability of fractures.

There are a multitude of osteoporosis screening and treatment guidelines, or position statements, of medical societies and advocacy groups such as the National Osteoporosis Foundation (NOF), American Academy of Orthopedic Surgery (AAOS), International Osteoporosis Foundation (IOF), National Bone Health Alliance (NBHA), Public Health Foundation Enterprises (4BoneHealth), the American Orthopaedic Association (AOA), the American College of Rheumatology (ACR) and American Academy of Family Physicians (AAFP). I find that these guidelines more or less echo the USPSTF and WHO recommendations.

 

Risk Factors

Numerous factors contribute to the development of reduced bone mass and micro-architectural deterioration that increases bone fragility and the likelihood of fractures. These include female gender, older age, sedentarism, lower body weight, amenorrhea, hormone abnormalities in general, smoking, excess alcohol use, poor nutrition, inadequate vitamin D intake, suboptimal calcium levels, corticosteroid use, hypogonadism, diabetes (types I & II), chronic kidney or liver disease, hyperparathyroidism, immune system disorders, sarcopenia (reduced muscle mass), infrequent exercise, and various pharmacologic agents. Genetics may have a role in bone health, but the natural process of aging itself and the social determinants of health - such as lifestyle - have a far greater influence on the overall burden of osteoporosis. 

Overload vs. Insufficiency Fractures 

We should make the distinction between overload and insufficiency fractures. Overload injuries occur when abnormal forces are applied to a normal system:  a fracture resulting from a motor vehicle accident or other traumatic injury. Insufficiency, or fragility, fractures typically occur when normal forces are applied to an abnormal system; pathologic or metastatic fractures; and, fractures associated with osteopenia and osteoporosis. An increasing number of Americans are now so unfit and overweight that they cannot tolerate the normal requirements of everyday life or work and in essence, suffer insufficiency injuries. 

The Female Triad

Osteopenia and osteoporosis are not only a dilemma for elderly female, but also for younger women afflicted by disordered eating, amenorrhea, and low bone mineral density. This constellation of symptoms, called the Female Triad, requires a medical team management approach. I once asked a prominent TRIAD physician if she thought it would be beneficial to do baseline DEXA studies on these patients, but she suggested it would be too emotionally stressful for the patient. I disagree. I think truth is always an essential part of medical management. These patients may benefit from the graphic color-coded imaging of DEXA and better value the symmetry of a healthy body composition. To rely on body mass index alone is confusing and inaccurate and fails to utilize available technology in a positive way to educate and inform. I find that BMI is an outdated metric and not good medicine.  

 

Current Treatment Options

At present, some doctors encourage women to take calcium supplementation of 1,000 – 1,200 mg/day as well as a minimum of 400 IU’s of vitamin D per day. Weekly or quarterly injections of drugs, such as denosumab, are often recommended as treatment for osteopenia or osteoporosis. Hormone therapies were in vogue for some time, but are less commonly used now due to concerns over increased risk of uterine cancer, breast cancer, stroke, blood clots and heart attack. Weight bearing exercises are encouraged with the knowledge that impact loading is a safer way to optimize bone density over a lifetime.

Fall prevention courses have justifiably been a main stay of osteopenia and osteoporosis management programs. If you don’t fall, the likelihood of a hip or wrist fracture is lessened significantly, but spinal compression fractures remain a common malady despite the avoidance of falls. Physical activity in general, regardless of the modality, remains far preferable to inactivity in maximizing bone health. Most osteoporosis medical groups advocate this approach.7,8

Bisphosphonates

Treatment with bisphosphonates became popular in the 1990s. They work by inhibiting the normal process of bone reabsorption so that the bone density appears to be greater. But this process inhibits the resorption of old bone rather than creating good new bone leaving behind the aging bone that needed to be resorbed. Abnormal fractures are noted to occur in the old bone.

Bisphosphonates, such as alendronate, ibandronate, risedronate and zoledronate disturb the normal equilibrium of bone resorption and deposition that admittedly is already significantly slowed with aging.  

Some side effects of concern include gastric irritation or erosions associated with the oral use of the drug, and the appearance of rare mandibular cancers. The New York Times recently wrote about the growing unwillingness of patients to take bisphosphonates due to complications.9

DEXA Technology

Dual energy X-ray absorptiometry (DEXA) was developed and pioneered in 1987. Hologic, GE, and Norland all make state of the art scanners to perform bone mineral density (BMD), and, with software upgrades, 3-compartment body composition adding body fat (BF%) and lean mass (LM%) assessment to BMD analysis. Initially pencil beam imaging was used which has now evolved into fan-beam scanners that obtain data in less than 10 minutes scan time. 

The International Society for Clinical Densitometry provides best practices guidance in the measurement and reporting of DEXA studies.10  The importance of systematic calibration and routine measurement of coefficient of variation metrics using phantom body models ensures a level of precision and accuracy within 1-2%.  Standardized patient scanning protocols ensure optimal study results.11

 

Radiation Concerns

The average annual “effective dose” of background radiation from cosmic and environmental exposures is about 3.0 mSv.  A CT scan of the pelvis, chest or abdomen can expose the patient to 6.0 -10.0 mSv in a single study (the equivalent of 2-3 years of environmental exposure in a single medical study). A CT scan of the head is 2.0 mSv.12 A lumbar spine X-ray series is 1.5 mSv and a single PA (posterior-anterior) chest X-ray (CXR) is ~0.06 mSv.  By comparison the radiation exposure of a DEXA scan is ~0.005 mSv, about a tenth of that from a single chest X-ray (CXR).13   

A patient would have to receive over 5,000 DEXA scans to approximate that of a single truncal CT scan. The precept of As Low As Reasonably Achievable (ALARA) in order to minimize radiation exposure is easily honored in the case of DEXA scanning due to the low mSv exposures. The Biological Effects of Ionizing Radiation (BEIR)VII report and executive summary provide definitive recommendations regarding radiation exposure and cancer risk.14   

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Bone Health Life Chart  

This article proposes a rethinking of how we prevent, diagnose, monitor and manage the continuum of osteopenia and osteoporosis. I recommend a baseline bone density study in childhood, one in the teen years, one at age 20 and serial screening at a minimum of 5 year intervals throughout life. Women reach maximum bone density in the 20s and by age 30. It makes little sense to utilize a T-score comparing a woman to an unrelated group of 30-year old women when she could be compared to herself at this age providing a true baseline metric. All women should have a “BMD & Body Composition Life Chart” that tracks her bone mineral density (specifically) as well as the percentages of her body fat (BF%) and lean mass (LM%). This offers the only really valid comparison for measuring the rate of bone change (gain or loss) over her lifetime. It is this knowledge that should guide the recommendations for physical activity throughout life to optimize a woman’s bone mineral density (BMD) and promote health and wellness.  

NHANES DEXA study 

There is precedent for DEXA testing at a young age. Between 1999-2004 the National Health and Nutrition Examination Survey (NHANES), working with Hologic, Inc (Bedford , MA), created a data base of DEXA scans of over 20,000 inpiduals from ages 8-85.15 The dataset collected DEXA whole body measures of BF%, fat mass, lean mass percentage, bone mineral content (BMC), bone mineral density (BMD), fat mass ratio and other measures. These reference values provide a baseline of information on which to build age stratified normal range metrics for fat, lean and bone measures. Further clinical trials and data accumulation will help elaborate our medical and epidemiologic knowledge.

 

Cost Containment 

DEXA studies can be performed for less than $100 and, in addition to BMD measurements, also provide accurate measurement of the patient’s lean body mass and percent body fat. This is vital information in terms of overall health. BMI is often used incorrectly as a surrogate for percentage of body fat. An inpidual with a BMI of 25 kg/m2 may have a body fat percentage of anywhere from 10 – 35 percent.  It is vitally important to have accurate and precise body metric data in managing a patient’s health care issues.  

To continue to use BMI when we have DEXA available is like listening to the heart with your ear on the patient’s chest when you could obtain an EKG and do a cardiac ultrasound. You can settle for it, but it is illogical and poor medicine. DEXA should be our state of the art tool for providing 3-compartment body composition analysis including bone mineral density (BMD), percent body fat (BF%), and percent lean mass (LM%).  

What We Should Do:  The BMD Life Chart

Every inpidual will lose bone mineral density as they age.  It is a consequence of aging. Unfortunately, women lose bone mass more precipitously than men. We know, however, that you can favorably influence the rate of bone loss over a lifetime. Doing so requires a eating healthy diet, taking supplements with calcium and vitamin D, avoiding risk factors, exercising habitually, and, optimizing muscle mass. However, once bone mass is lost, it is most likely a permanent loss, so prevention is essential. 

Women should track their bone density throughout their life and have their first bone scan in her twenties or by 30 years. Ideally, we should start DEXA scans prior to adolescence so that we can advise and provide guidance to maximize a woman’s BMD throughout her life. Starting at age 10 with a scan every five years would provide a meaningful and vital BMD and Body Composition Life Chart. In this way, the patient knows her peak bone density and is not compared to an amorphous group of 30-year old white females. The woman becomes - authentically - her own T-score comparison for before and after evaluation. Patients have one chance to measure BMD at a young age and when this opportunity is missed, they have no legitimate BMD baseline.

 

Ralph S. Bovard, M.D., MPH, FACSM

Clinical Program Director

Occupational & Environmental Medicine Residency

HealthPartners Medical Group & University of Minnesota School of Public Health

 

Additional Reading

The following three references are relevant to this discussion. James Fries MD landmark article, “Aging, Natural Death, and the Compression of Morbidity” was published in the NEJM (303:130-135) in 1980 in which he defined the concept of the rectangular survival curve.   Nortin M. Hadler, M.D., author of, “Rethinking Aging,” encourages us to challenge medical expert opinion, question our scientific literature (particularly in terms of relative vs absolute risk), and to pursue quality of life issues passionately - especially in later years. Walter M. Bortz II, M.D., a distinguished expert on aging and longevity of Stanford University, is the author of “Next Medicine: The Science and Civics of Health,” which I found to be an inspiration.

References:

(1) Wright NC1, Looker AC, Saag KG, Curtis JR, Delzell ES, Randall S, Dawson-Hughes.  J Bone Miner Res. 2014 Nov;29(11):2520-6. DOI: 10.1002/jbmr.2269. “The recent prevalence of osteoporosis and low bone mass in the United States based on bone mineral density at the femoral neck or lumbar spine.” http://onlinelibrary.wiley.com/doi/10.1002/jbmr.2269/abstractB (2) Am Fam Physician. 2011 May 15;83(10):1197-1200. (3) Blume SW, Curtis JR.  Medical costs of osteoporosis in the elderly Medicare population. Osteoporos Int. 2011 Jun;22(6):1835-44.  doi: 10.1007/s00198-010-1419-7. Epub 2010 Dec 17. (4) Kolata, G. "Bone Diagnosis Gives New Data But No Answers". New York Times; September 28, 2003. (5) Final Recommendation Statement: Osteoporosis: Screening- US Preventive Services Task Force.  Annals of Internal Medicine. January 11, 2011. https://www.uspreventiveservicestaskforce.org/Page/Document/UpdateSummaryFinal/osteoporosis-screening 6) WHO Scientific Group on the Prevention and Management of Osteoporosis (2000 : Geneva, Switzerland) (2003). (7) Tonnesen R, Schwarz P, Hovind PH, Jensen LT.  Physical exercise associated with improved BMD independently of sex and vitamin D levels in young adults. Eur J Appl Physiol. 2016 Jul;116(7):1297-304. doi: 10.1007/s00421-016-3383-1. Epub 2016 May 5. (8) Kohrt WM, Bloomfield SA, Little KD, Nelson ME, Yingling VR (November 2004). "American College of Sports Medicine Position Stand: physical activity and bone health." Med Sci Sports Exerc. 36 (11): 1985–96. doi:10.1249/01.mss.0000142662.21767.58 (9) Kolata, G. “Osteoporosis Drugs Shunned for Fear of Side Effects,” New York Times, Thursday, June 2, 2016. (10) Lewiecki EM, Binkley N, Morgan SL, et al.  Best Practices for Dual-Energy X-ray Absorptiometry Measurement and Reporting: International Society for Clinical Densitometry Guidance.  Journal of Clinical Densitometry: Assessment & Management of Musculoskeletal Health. 2016;19 (2):127-140. (11) Nana A, Slater GJ, Hopkins WG, et al.  Importance of Standardized DXA Protocol for Assessing Physique Changes in Athletes.   Int J Sport Nutr Exerc Metab. 2016 Jun;26(3):259-67.  doi: 10.1123/ijsnem.2013-0111.  Epub 2014 Jan 17. (12) Fazel R, Krumholz HM, Wang Y, et al.  Exposure to Low-Dose Ionizing Radiation from Medical Imaging Procedures.  NEJM.  2009; 361:849-857.  August 27, 2009 DOI: 10.1056/NEJMoa0901249 (13) Lewiecki EM, Binkley N, Morgan SL, et al.  Best Practices for Dual-Energy X-ray Absorptiometry Measurement and Reporting: International Society for Clinical Densitometry Guidance.  Journal of Clinical Densitometry: Assessment & Management of Musculoskeletal Health. 2016;19 (2):13 (14) Health Risks from Exposure to Low Levels of Ionizing Radiation: BEIR VII Phase 2 (2006).  https://www.nap.edu/read/11340/chapter/2 (15) Kelly TL, Wilson KE, Heymsfield SB.  Dual Energy X-Ray Absorptiometry Body Composition Reference Values from NHANES. (2009)  PLoS ONE 4(9): e7038. doi:10.1371/journal.pone.0007038