New insights on current osteoporosis risk assessment
9 October 2017:
Once upon a time, not too many years ago, osteoporosis was defined as having a history of low-trauma, major site fracture. Then came the high technology era and DXA machines were introduced all over the world. By testing large populations, sex-, ethnic-, age- and weight-adjusted bone density (BMD) averages were calculated, which allowed new definitions of osteoporosis (by T-score), and comparison of the individual values with the adjusted average values in their community (Z-score). Still, because most people who fracture do not have osteoporosis and most people with osteoporosis do not break their bones, a more sophisticated method to measure the risk for fractures seemed reasonable. Furthermore, new medications to prevent fractures have been developed and commercialized, adding a substantial financial burden to health budgets, thus putting cost-effectiveness as a top priority issue. As a result, it became evident that prescribing therapies must be based on accurate prediction of individual risk for future major osteoporosis-related fractures. Incorporation of various risk factors for osteoporosis or for fractures led to the creation of screening tools, with or without BMD data, which claimed to have higher predictive values [1]. FRAX® is probably the most recognized risk assessment tool, as it also takes into consideration the local situation, based on data raised in the particular country or region.
Several recent publications have explored the value of the risk calculators in determining the need for intervention. For example, a FRAX® tool, calibrated for Kuwait, found that when a BMD T-score of -2.5 SD was used as an intervention threshold, FRAX® probabilities of a major osteoporotic fracture in women aged 50 years were approximately two-fold higher than those in women of the same age but with an average BMD [2]. However, at the age of 83 years or more, a T-score of -2.5 SD was associated with a lower probability of fracture than that of the age-matched general population with no clinical risk factors. What is missing, of course, is the validation of these results, namely a long-term follow-up to see whether these probabilities will eventually prove accurate. The US National Osteoporosis Foundation (NOF) guidance recommends initiation of treatment in the following three scenarios, based on available national epidemiological data [3]: (a) in those with hip or vertebral (clinical or asymptomatic) fractures; (b) in those with T-scores less than or equal to −2.5 at the femoral neck, total hip or lumbar spine by DXA; (c) in postmenopausal women and men aged 50 years old or older with low bone mass (T-score −1.0 to −2.5, osteopenia) at the femoral neck, total hip or lumbar spine by DXA and a 10-year hip fracture probability of 3% or more or a 10-year major osteoporosis-related fracture probability of 20% or more based on the US version of FRAX®. A more recent review presented a global approach and discussed the current knowledge at length, pointing at the complexity of optimizing a stepwise approach to case-finding of individuals who are at high risk of sustaining fragility fractures [4]. It seems quite obvious that health systems will strive for better algorithms or models to identify those who are really at high risk for future major osteoporosis-related fractures. Apparently, new softwares that will use electronic records of patients and incorporate more risk parameters, either laboratory, imaging or even genomic testing, will allow better clinical decisions as to whom to treat and perhaps what would be the preferred personalized therapeutic approach [5)].
Amos Pines
Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
References
- Edwards BJ. Osteoporosis risk calculators. J Clin Densitom 2017 Jul 21. Epub ahead of print
http://www.ncbi.nlm.nih.gov/pubmed/28739082 - Johansson H, Azizieh F, Al Ali N, et al. FRAX- vs. T-score-based intervention thresholds for osteoporosis. Osteoporos Int 2017 Aug 7. Epub ahead of print
http://www.ncbi.nlm.nih.gov/pubmed/28782072 - Cosman F, de Beur SJ, LeBoff MS, et al. Clinician's guide to prevention and treatment of osteoporosis. Osteoporos Int 2014;25:2359-81
http://www.ncbi.nlm.nih.gov/pubmed/25182228 - Harvey NC, McCloskey EV, Mitchell PJ, et al. Mind the (treatment) gap: a global perspective on current and future strategies for prevention of fragility fractures. Osteoporos Int 2017;28:1507-29
http://www.ncbi.nlm.nih.gov/pubmed/28175979 - Baim S. The future of fracture risk assessment in the management of osteoporosis. J Clin Densitom 2017 Jul 20. Epub ahead of print
http://www.ncbi.nlm.nih.gov/pubmed/28735781