Experts Raise Questions on Diagnosing and Treating Low Bone Mass
BY LAUREN UZDIENSKI, SEPTEMBER 8, 2009
An article in the New York Times this week discussed osteopenia, a controversial diagnosis made when bone density is lower than average but does not meet the clinical criteria for osteoporosis. Osteopenia was defined by the WHO in 1994, and last year the agency released the FRAX program to aid physicians in its diagnosis and treatment planning.
Osteopenia is thought to be a precursor to osteoporosis, a dangerous weakening of the bones that predisposes the patient to fractures. Recent data on osteoporotic hip fractures reiterated the relationship between fractures and death, so slowing the onset of osteoporosis as well as managing the condition effectively is a key priority for physicians and patients.
However, the exact link between osteopenia and fracture risk has not been determined, so some physicians are questioning the necessity of prescribing bone-preserving drugs to treat the condition. The FRAX calculation is an effort to evaluate factors other than bone density scores in assessing patients at risk for fractures, though the test may be inadvertently lowering the threshold for drug prescriptions and causing patients to worry needlessly about the likelihood of a fracture.
Several concerns have been raised in regard to FRAX. The method by which the score is calculated has not been released to the public, with some critics arguing that the WHO's secrecy over the formula makes the program's validity impossible to assess. While the multi-factorial calculation offers an opportunity for a bigger picture than just a bone density scan, the Times reports that certain factors contributing to bone loss, including vitamin D deficiency, physical activity and use of epilepsy drugs and antidepressants, are excluded from the FRAX analysis. Other factors, like smoking and drinking, may be over or underweighted in the results, because the program does not ask how much a patient smokes or drinks and how long they've been doing so. A couple of studies to validate the FRAX method found that either more research was needed before clinical implementation or that the factors FRAX evaluates beyond bone density and age do not help predict vertebral fracture risk.
As for bone density scans and the clinical definition of osteopenia, some physicians are unsatisfied with the results scale and the threshold for medication. Bone density scans compare a patient's current bone density to the young adult mean; within one standard deviation below this mean is normal, below one standard deviation suggests osteopenia, and more than 2.5 standard deviations below the young adult mean suggests osteoporosis. It has been argued that the one-point standard deviation is an arbitrary marker for the osteopenia diagnosis and that the label can be applied too quickly, leading to unnecessary medication or anxiety in patients. One recent study cited by the Times found that osteoporosis drugs were "largely ineffective and unnecessary" in osteopenia patients. This is significant given the possible side effects of the drugs, which include GI problems and potentially osteonecrosis of the jaw in Fosamax.
Merck, who manufactures Fosamax, estimated in 2003 that eight million people have osteopenia and that about a third of them are taking medication to treat it; the Times reports that since 2003, sales of osteoporosis drugs have doubled to about $8.3 billion annually. This demonstrates a sense of patient urgency and an uptick in prescriptions, though the data seem to indicate that patient risk factors for osteoporosis should be carefully considered against challenges to bone drugs' efficacy.
