Osteoporosis (definition): Disorder characterized by low bone mass and micro architectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk.
The last several columns looked at Vitamin D’s role in bone health, morbidity and mortality associated with fracture and risk reduction strategies by looking at fall prevention in your home. This column will look at how osteoporosis is diagnosed and the proven pharmacologic interventions considered standard of care to reduce fracture risk.
DEXA scan (or bone scan) a low dose x-ray assessing bone mineral density (BMD) typically of the lumbar spine and hip, is the only test on which to base treatment. Results from other technologies or scans from other body sites (wrist or ankle), cannot be used according to the WHO diagnostic classification because they are not equivalent to results derived from DEXA. A normal DEXA result is within 1 standard deviation of a young adult reference population (T score at -1.0 and above). Low bone mass (osteopenia) is between 1.0 and 2.5 standard deviations of a young adult reference population (T score between -1.0 and -2.5). Severe bone loss (osteoporosis) is more than 2.5 standard deviations below that of a young reference population (T score greater then -2.5). Any person who has osteoporosis (T greater than -2.5) or sustained a hip or vertebral fracture in the absence of major trauma (such as MVA or multiple story fall) regardless of bone mineral density deserves medical therapy according the National Osteoporosis Foundation (www.nof.org).
Who to screen can sometimes be a matter of opinion. The NOF recommends that all women over 65 years old and post-menopausal women aged 50- 64 years old with 1) fracture during adulthood 2) condition (i.e. rheumatoid arthritis) or medication (chronic steroid use) associated with low bone mass 3) women less then 65 years old whose 10-year risk of osteoporotic fracture is equal or greater than that of a 65-year-old white woman who has no additional risk factors. FRAX is the WHO fracture risk assessment tool that can be used with and without DEXA results to calculate that 10-year risk. The FRAX (https://www.shef.ac.uk/FRAX/) website can help calculate the 10-year risk for both major vertebral fracture and hip fracture. If your risk for a major fracture is 20% or greater or hip fracture is 3% or greater, you should be offered medicine efficacious at reducing your risk for fracture. Last month’s column spoke about the morbidity and mortality within one year of a fracture which is why you should know if you are at risk.
If you have osteoporosis or a FRAX score greater than 20% or 3% then simply taking Vitamin D and getting regular weight bearing exercise is not enough. You will continue to lose bone which will only increase your fracture risk over time. There are several medicines used in the prevention and treatment of osteoporosis, bisphosphonates are considered the first line of defense to reduce your risk for fracture. These medicines reduce bone loss by inhibiting the cells in bone that are responsible for bone resorption.
Bisphosphonates come in oral and injectable forms and some that are dosed weekly, monthly, or annually. They are considered safe to use for between 3-5 years after which many patients take a drug holiday for a few years. Their use is on average responsible for an 80% reduction is risk for fracture. They are not without side effects most common being indigestion. The most talked about fears and reason cited for not taking a bisphosphonate is osteonecrosis of the jaw (ONJ) which is a rare complication and typically occurs in cancer patients on very high doses greater than that recommended for fracture prevention. Over 90% of the reported cases of ONJ have been in cancer patients receiving bisphosphonate doses 10X high then used to treat osteoporosis. Estimated incidences of ONJ in patients with osteoporosis is between 1:10,000 – 1: 100,000.
The less talked about fear and second reason patients are reluctant to take a bisphosphonate has been their association with atypical femur shaft fractures. These are thought to occur from over-suppression of bone turnover in patients exposed to bisphosphonates for longer the 3-5 years. A drug-free period may be considered after 3 years of IV zoledronic acid or 5 years of oral alendronate. The absolute risk increase in femur fractures from bisphosphonate therapy is 5 cases in 10,000 patient years.
What is often not known is that other than reducing the risk of hip and vertebral fracture, bisphosphonates “SIDE BENEFITS” are decreased risk of breast cancer, colorectal cancer, stroke, myocardial infarction, gastric cancer and overall mortality in users compared to non-users. This is why it is important to talk with your doctor about your bone health and know that there are safe medicines that can be prescribed to reduce your risk for fracture. That is why bone health matters.