Epidemiology of Osteoporosis: Applying Relevant Figures to your Practice!

Pierre Guy, MDCM, MBA, FRCSC
Vancouver, BC

What if this article revealed:

  • how much more of a problem osteoporosis is than you think?
  • how much more often your total hip beds will blocked by hip fracture patients in the future?
  • how much an osteoporotic fracture increases the risk of another fracture, and increases mortality risk for a patient?
  • how much you could influence the occurrence of an osteoporotic fracture by adding a simple statement to your consult letter?

Osteoporosis, as a diagnosis, unfortunately, usually comes to mind for most of us only after a patient presents with a hip fracture. In fact, we often overlook this diagnosis in elderly patients as we focus more on the medical co-morbidities which might delay surgery, and the social conditions which might delay discharge. However, if we look closely at a hip fracture patients history, if we critically examine her wrists, and scrutinize the chest X-ray, we discover the missed opportunities orthopaedic surgeons have had to intervene to prevent future fractures. Sentinel fractures of the distal radius and proximal humerus, not to mention the contralateral hip fracture, would have been seen by an orthopaedic surgeon in many cases. Yet rarely have we intervened by suggesting testing, prescribing treatment, or by directing the patients family physician to do so.

This is why targeted knowledge on the epidemiology of osteoporosis and related fractures could go a long way to improving your approach to fragility fracture patients. You could also use this information to warn your local health care administrator of the epidemic to come. Having identified the high risk population in the previous section, the present article will answer the practical questions stated above: How big a problem is this? What does it mean to individuals, to your hospital and society, and to your practice?

Applied Epidemiology
It is estimated that one in three women and one in five men over the age of 50 worldwide have osteoporosis. The prevalence of low BMD is closely related to age. Kanis et al.3 have long since demonstrated this increased prevalence with age (Figure 1).

pguyfig1.jpg

Low BMD alone is important but individuals who additionally have risk factors for falling (risk factors: older age, low body weight, dementia, institutionalized dwelling status, poor vision or balance, poor muscle strength) have substantially increased risk of sustaining a hip fracture.

The type and incidence of fragility fracture is in fact related to age and sex. Figure 2 from Cooper et al. demonstrates that both men and women show an age-adjusted increase in hip fracture incidence. The incidence of distal forearm (radius) fractures progressively increases in older women while it appears to level off with agein men.

pguyfig2.jpg

This strong correlation with age heralds a major increase in the volume of cases as the Baby Boomer generation ages with a bottleneck effect as the demand for hospital beds increases. Papadimitropoulos et al.4 mapped out the projected number of cases of hip fractures in Canada by 2041 based on the number of proximal femur fractures (PFFs) from CIHI data and the population projections from Statistics Canada. They projected the number of PFFs would increase 3.7X (from 23 375 to 88 124 cases) with an even higher increase (3,87X) in patient-days length of stay.

While vertebral fractures are the most common (US incidence (cases/yr): vertebra: 700 000, hip 300 000, radius 200 000), and their presence increases the risk of hip fracture5, orthopaedic surgeons are not usually involved in outpatient vertebral fracture care. We more commonly see in consultation patients with fragility fractures to the extremities. Women over 50 have a 17.5% lifetime risk of sustaining a hip fracture, 16% lifetime risk of a wrist fracture and an overall 40% lifetime risk of sustaining a fragility fracture6. As we noted, the volume of cases is important from a societal point of view, but on an individual level the occurrence of a fracture also places one at risk of a subsequent fracture. Table 1 defines the risk of a sustaining a subsequent fracture following a prior fragility fracture1. All fractures demonstrate an increased risk but note that wrist fractures, which are sustained on average at a younger age, almost double the risk of a subsequent hip fracture, compared to the normal population.

pguyfig3.jpg

Of additional interest is the increased mortality of fragility fracture patients compared to the population. Table 2 illustrates the increased Relative Risk of Mortality to be highest following a hip or spine fracture2.

guytable2.jpg
This increased mortality along with the projected increased incidence call us to action before the Baby Boomers reach the hip fracture age-range4- and while we still have an opportunity to identify individuals at an early stage.

In this respect, we have not taken advantage of the opportunity offered by these clinical encounters with sentinel fractures to initiate diagnosis and treatment of osteoporosis. The details of therapy are planned for Part II of this series. Of note, however, is the tremendous change an orthopaedic surgeon can effect in the diagnosis and treatment of osteoporosis by a simple change in his or her everyday practice. Two randomized controlled trials from our centre (WristWatch and HipWatch)7-9 have shown that the simple mention of osteoporosis in a letter sent back to a patients family physician will increase the rate of diagnosis and the initiation of treatment from 18% to 92% following a wrist fracture7,8 and from 0% to 70% following a hip fracture9.

In summary, this article provides the orthopaedic surgeon epidemiological data which can be applied to the care of his or her patients, and be used in discussion with health administrators. The figures to remember are:

- 17.5% (or about 1 out of 5: for the lifetime risk a 50 yo female has of sustaining a hip fracture)
- 4 (for the fourfold projected increase in the number of hip fracture cases over the coming years)
- 2 (for the doubling in hip fracture risk each distal radius fracture patient you see this week)
-7 ( which is the sevenfold increased in age-adjusted mortality following a hip fracture)
- 5X and more (for the improvement in the rate of diagnosis and treatment you will affect by simply adding a comment to family physicians about the need to investigate and treat osteoporosis every time you see a patient with a fragility fracture.

References

  1. Klotzbuecher, C.M., Ross, P.D., Landsman, P.B., Abbott, T.A., 3rd, Berger, M (2000) Patients with prior fractures have an increased risk of future fractures: a summary of the literature and statistical synthesis. J Bone Miner Res 15:721-739
  2. Cauley, J.A., Thompson, D.E., Ensrud, K.C., Scott, J.C., Black, D. (2000) Risk of mortality following clinical fractures. Osteoporos Int 11:556-561
  3. Kanis, J.A. (1994) Assessment of fracture risk and its application to screening for postmenopausal osteoporosis: synopsis of a WHO report. WHO Study Group. Osteoporos Int 4:368-381
  4. Papadimitropoulos, E.A., Coyte, P.C., Josse, R.G., Greenwood, C.E. (1997) Current and projected rates of hip fracture in Canada. CMAJ 157:1357-1363
  5. Black, D.M., Arden, N.K., Palermo, L., Pearson, J., Cummings, S.R. (1999) Prevalent vertebral deformities predict hip fractures and new vertebral deformities but not wrist fractures. Study of Osteoporotic Fractures Research Group. J Bone Miner Res 14:821-828
  6. Melton, L.J., 3rd, Chrischilles, E.A., Cooper, C., Lane, A.W., Riggs, B.L. (1992) Perspective. How many women have osteoporosis? J Bone Miner Res 7:1005-1010
  7. Ashe, M., Khan, K., Guy, P., Kruse, K., Hughes, K., O'Brien, P., Janssen, P., McKay, H. (2004) Wristwatch-distal radial fracture as a marker for osteoporosis investigation: a controlled trial of patient education and a physician alerting system. J Hand Ther 17:324-328
  8. Ashe, M.C., McKay, H.A., Janssen, P., Guy, P., Khan, K.M. (2005) Improving osteoporosis management in at-risk fracture clinic patients. J Am Geriatr Soc 53:727-728
  9. Davis, J., Guy, P., Jannsen, P., Ashe, M., Khan, K. (2006) HipWatch: Osteoporosis Treatment and Investigation after a Hip Fracture: A 6-Month Randomized Controlled Trial. In: Canadian Orthopaedic Association/ Canadian Orthopaedic Research Society Annual Meeting. Toronto

 

Submit Community Content

If you have orthopedic information that you would like to share with the Orthogate Community, please register/login and submit your news, event, job, article, case or workshop from the Submit Content menu under the My Account area. Learn more!