Predicting Future Fracture Risk

For those suspected of suffering from poor bone health, the Fracture Risk Assessment Tool, also called FRAX®, is a valuable and cost-effective diagnostic technique for evaluating future risk for fractures.

Developed by the World Health Organization Task Force in 2008, FRAX® provides guidance to physicians treating patients with osteoporosis [ostē-ō-pō-rōsis] (osteo=bone, porosis=porosity or thinness), a condition involving a gradual loss of calcium resulting in bones becoming thinner, more fragile and more likely to break – particularly the hip, spine and arm. It’s a common condition that typically affects postmenopausal women and the elderly and can severely affect quality of life.

FRAX® is an easyto-use computer program that can predict the probability of an osteoporotic fracture – a lowimpact fracture – within a 10-year period in patients. FRAX® determines how dense one’s bones are through a bone mineral density (BMD) test in combination with other factors, including where a patient lives and their ethnic background. Additional risk factors considered along with a medical history and physical exam include:

  • Age – older adults are at a greater risk of fractures than younger adults
  • Body weight and height – a slender frame or being underweight increases risk
  • Prior fracture
  • A family history of fracture
  • Use of steroid medications like prednisone, particularly in high doses and for more than several months
  • Rheumatoid arthritis or other conditions known to cause osteoporosis
  • Smoking tobacco
  • Drinking too much alcohol

The more clinical risk factors there are, the greater the risk of having a fracture.

PRE-FRAX® TESTING

Before FRAX®, the most common and accurate way to assess the risk of a person having a fracture was through BMD testing, which measures the density of calcium in the bones through a dual energy X-ray (DEX) absorptiometry scan. A person’s BMD value is compared to the ideal or peak BMD of a healthy 30-year-old of the same gender to determine the risk of developing a fracture. The differences in the BMD results are measured in units called standard deviations. The more standard deviations below zero (indicated as negative numbers), the lower your BMD and the higher your risk of fracture.

BMD test results are typically given a T-score and Z-score. A T-score of 0 means your BMD is equal to that of a healthy young adult, and the score is within the normal range if it is -1.0 or above. A score between minus one and minus 2.5 is classified as having osteopenia (low bone mass), while a score below minus 2.5 (more negative) is defined as osteoporosis.

The Z-score reflects the amount of bone you have compared with others in your age group who are of the same size and gender. If the score is unusually high or low, it may indicate a need for further medical tests.

While FRAX® is not a replacement for BMD testing, it is another resource to help identify risk factors. It provides a framework for physicians to calculate a patient’s susceptibility for a fracture risk and determine if a BMD test and/or treatment will be needed.

WHY USE FRAX®?

Several diseases, such as diabetes and hypertension, are defined by measuring clinical risk factors. For example, hypertension is diagnosed by measuring blood pressure levels as a means of assessing the risk of stroke. Elevated blood glucose (sugar) helps define the risk of diabetes. And increased blood cholesterol is used to help assess the risk of a heart attack.

With osteoporosis, a BMD measures the degree of bone mass or density, and a low or very low value helps provide information on bone fracture risk. Fracture risk increases with bone loss and is highest when the BMD is in the osteoporosis range. However, more than half of all fractures affect women with only mild bone loss (osteopenia) due to the presence of other risk factors for fracture. BMD only captures one aspect of fracture risk, i.e., bone density, or how thin the bone is, and defining the risk of a future fracture is improved using FRAX® technology. The use of FRAX® provides additional information to assist doctors in assessing fracture risk and to help determine when drug treatment should be recommended.

HOW SHOULD FRAX® BE USED?

FRAX® is not intended for use in persons who have BMD values in the osteoporosis range or for those who have had a previous hip or spine (vertebral) fracture, as they are already candidates for treatment. Also, FRAX® should not be used for patients already receiving osteoporosis medications.

The FRAX® algorithms give the 10-year probability of hip fracture and the 10-year probability of a major osteoporotic fracture (clinical spine, forearm, hip or shoulder fracture). It’s important to note that not all additional risk factors for fractures, such as frequent falls, are represented in the FRAX® score.

Postmenopausal women and men with FRAX® clinical risk factors should contact their doctor to see if they are candidates for a BMD measurement. Physicians can also use the FRAX® tool in patients with a BMD value in the osteopenia range to calculate a 10-year fracture risk score and help assess if medication is indicated to reduce future fracture risk.

If your bone density is lower than normal, you can increase bone density and strength by exercising, lifting weights or using weight machines, getting sufficient calcium and vitamin D, and taking some medicines.

Dr. Daniel L. Hurley is a consultant in the Division of Endocrinology, Diabetes, Metabolism and Nutrition in the Department of Internal Medicine at Mayo Clinic, Rochester and is also an Assistant Professor of Medicine with the Mayo Clinic College of Medicine. He received his endocrine research training in bone and mineral metabolism and was awarded the Randall G. Sprague Award for Outstanding Achievement as an Endocrine Fellow. He also has been recognized with the Department of Medicine Teacher of the Year Award and the Henry S. Plummer Distinguished Physician Award. His clinical interests include metabolic bone disease and nutritional health.