That is the finding from a new report funded by the U.S. government's Agency for Healthcare Research and Quality (AHRQ).
Based on an analysis of studies examining the risks and benefits of six bisphosphonates and other osteoporosis drugs, researchers concluded that while many medications reduced the risk of bone fractures in people with osteoporosis, no single drug or drug class was clearly superior.
They noted that there was not enough data to determine if the bisphosphonates were better for preventing fractures than hormone-based treatments.
The researchers included in their analysis studies involving Fosamax, Boniva, four other bisphosphonates (Didronel, Aredia, Actonel, and Reclast), the man-made hormone calcitonin, the selective estrogen receptor modulators Evista and tamoxifen, parathyroid hormone, estrogen, testosterone, calcium, and vitamin D.
"The fact is, there have been very few head-to-head trials done to compare any of these agents," study author Catherine MacLean, MD, PhD, of the RAND Corp., tells WebMD. "It is expensive to do these trials. On the other hand, these are also expensive agents, and as consumers we have the right to know which ones work best."
Many Patients Stop Treatment
The studies indicated that the effectiveness of calcium and vitamin D varied according to the dosage taken, how often the supplements were taken, and whether osteoporosis patients were at high risk for fractures.
Researchers also found compliance to be a problem with most osteoporosis treatments and for calcium and vitamin D, which must be taken every day. Patients were more likely to stay on longer-acting bisphosphonate treatments than those that had to be taken daily.
At least one calcium study showed the supplement to benefit patients who took it daily as directed, but not patients who took it less often than was recommended, MacLean points out.
"As with any therapy, these treatments don't work unless you take them," she says.
No single bisphosphonate was found to be superior to another for preventing bone fractures.
The analysis was published online Monday and will appear in the Feb. 5 edition of the Annals of Internal Medicine.
More Study Needed
An official with the AHRQ says the report helps shed light on what is known and not known about the effectiveness and safety of osteoporosis treatments.
"Without question we need more studies examining the effectiveness of different treatments," Jean Slutsky tells WebMD. "There is a lot of uncertainty about how the supplements compare to the other therapies and how the [prescription] drugs compared to each other."
This research is important, Slutsky says, because so many people elderly people are at risk for osteoporosis and frequently life-altering fractures related to bone weakening.
"About half of women over 50 will suffer an osteoporosis-related bone break in their lifetime," she says. "We have all heard stories about older people who were doing great until they fell and broke a hip and went into a steady decline."
She adds that while it isn't clear which medications work best, it is clear that most treatments do help reduce fracture risk when taken regularly.
"[Osteoporosis] is a largely treatable condition," she says.
Calls to Fosamax manufacturer Merck & Co. and Boniva manufacturer Hoffmann-LaRoche were not returned by publication time.