The risk of fracture increases with decreasing bone mineral density (BMD), and fracture risk is highest in subjects with osteoporosis. However, most patients at the time of a fracture have no osteoporosis, even in the presence of a low-trauma fragility fracture. The reasons for this discrepancy are multiple. Firstly, BMD is only one of the many bone components that contribute to bone’s resistance to fracture (macro- and micro-architecture, mineralization, collagen cross-linking, etc.). Secondly, clinical risk factors (age, gender, personal or family history of fracture, life style, diseases and medications) and extra-skeletal factors (propensity to fall) increase the risk of fractures, independent of BMD. Thirdly, it is known that at the population level only limited patients with disease have a high risk (the so-called “prevention paradox”). Fourthly, the WHO definition of osteopenia was developed for epidemiological research and the WHO limited a definition of fracture to patients with “established osteoporosis” if they had a fragility fracture and osteoporosis, but not in case of osteopania. Fifthly, in circumstances such as the use of glucocorticoids, fracture risk is at any BMD higher than in postmenopausal osteoporosis.
The diagnosis and treatment options in patients with osteopenia are a challenge in daily practice. On the one hand, osteopenia is a frequent finding in the 50+ population and in fracture patients. On the other hand, several drugs are available that decrease the risk of fractures, but these drugs are usually only prescribed in the high-risk group of osteoporotic patients, but not in the much larger group of individuals with osteopenia.
Randomized clinical trials (RCTs) with fracture prevention as primary endpoint included patients with osteoporosis, but also patients with osteopenia when they were selected on the basis of a prevalent vertebral fracture (VF) (without a BMD inclusion criterion or with a BMD threshold criterion in the osteopenic range), a recent hip fracture or clinical risk factors.
Data from RCTs indicate that anti-osteoporotic drug treatment could be effective in patients with osteopenia in the presence of other risk factors, such as a prevalent VF, a recent hip fracture, use of glucocorticoids or other clinical risk factors.
Prescription of drugs to all osteopenic patients would certainly lead to overtreatment with unnecessary side effects and costs. Most guidelines on fracture prevention therefore advocate in patients with osteopenia an evaluation for the presence of other risk factors, such as the presence of a VF by imaging of the spine, recent falls or high fracture risk based on FRAX. They advocate in osteopenic patients life style adaptations, adequate intake of calcium and vitamin D, treatment of eventual underlying diseases, and medical treatment in the presence of one or more of these risk factors.
New techniques for identifying patients with osteopenia at high fracture risk are studied, such as bone micro-architecture and cortical porosity by high-resolution peripheral quantitative computer tomography (HRpQCT).
However, in the absence of RCTs in patients with osteopenia selected on the basis of a high risk of fractures, medical treatment decisions have only limited evidence in terms of fracture prevention, except in the presence of a prevalent VF.
Osteopenia is not a disease. It is frequently found in patients with a fracture, but is only one of the risk factors that contribute to fracture risk. Further research will be needed to identify bone-related parameters to identify patients with osteopenia with a high fracture risk, such as architectural changes by HRpQCT. RCTs with fracture prevention as primary endpoint will be needed to achieve higher levels of evidence for optimal treatment decisions in patients with osteopenia according to their fracture risk.
Disclosure of Interest None Declared
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