From the Guidelines
T-scores and FRAX risk calculations can appear contradictory because they measure different aspects of bone health, with T-scores below -2.5 indicating severe osteoporosis based solely on bone mineral density (BMD), while FRAX risk scores incorporate multiple factors beyond BMD, including age, weight, family history, smoking status, alcohol use, and other clinical risk factors 1. This discrepancy often occurs in younger postmenopausal women who have low BMD but fewer additional risk factors for fracture.
- The World Health Organization (WHO) criteria define a T-score value less than or equal to -2.5 at the lumbar spine, one-third (33%) radius, femoral neck, or total hip as consistent with osteoporosis 1.
- FRAX risk scores, on the other hand, predict future fracture probability based on multiple clinical risk factors, including age, weight, family history, smoking status, alcohol use, and other factors 1. Despite low FRAX scores, treatment is typically recommended for patients with T-scores in the severe osteoporosis range (-2.5 or lower), especially if there's a history of fragility fractures.
- First-line medications include bisphosphonates like alendronate (70mg weekly), risedronate (35mg weekly), or zoledronic acid (5mg IV yearly), along with calcium (1000-1200mg daily) and vitamin D (800-1000 IU daily) supplementation 1. The decision to treat should balance the long-term benefits of preventing fractures against potential medication side effects.
- BMD reflects current bone status, while FRAX predicts future fracture probability, explaining why these two measurements can sometimes tell different stories about a patient's bone health 1. It is essential to consider the patient's overall clinical profile, including their T-score, FRAX risk score, and other risk factors, when making treatment decisions 1.
From the Research
T Scores and FRAX Risks
- T scores are used to indicate the severity of osteoporosis, with a score of -2.5 or lower indicating severe osteoporosis 2, 3, 4.
- However, T scores alone do not capture the full range of fracture risk, as they do not take into account other clinical risk factors 3, 5.
- The FRAX (Fracture Risk Assessment Tool) is a more comprehensive tool that calculates the 10-year probability of major osteoporotic fracture and hip fracture based on clinical risk factors and bone mineral density (BMD) 3, 5.
- It is possible for a patient to have a low T score indicating severe osteoporosis, but a low 10-year FRAX risk, if they do not have other clinical risk factors that contribute to fracture risk 3, 5.
Clinical Risk Factors
- Clinical risk factors that contribute to fracture risk include age, sex, family history of osteoporosis, and presence of fragility fractures 3, 5.
- The presence of one or more fragility fractures is a strong indicator of increased fracture risk, regardless of T score 6, 4.
- Other risk factors, such as low body mass index, smoking, and excessive alcohol consumption, can also contribute to increased fracture risk 6.
Treatment and Management
- Treatment of severe osteoporosis typically involves pharmacological therapy, as well as lifestyle modifications such as exercise, calcium and vitamin D supplementation, and fall prevention 2, 6.
- The goal of treatment is to reduce the risk of future fractures and improve outcomes, rather than simply to improve T scores 2, 6.
- In some cases, surgical treatment may be necessary, particularly in cases of advanced severe osteoporosis with multiple fragility fractures 4.