TUESDAY, May 20, 2003 (HealthDayNews) -- Hormone therapy used in tandem with the drug alendronate boosts bone mineral density in older women better than either therapy alone does.
That's the conclusion of a study appearing in the May 21 issue of the Journal of the American Medical Association.
Bone mineral density is a key indicator of whether a person suffers from osteoporosis.
"Hormone replacement provides a benefit when combined with alendronate," says study author Dr. Susan Greenspan. "For women who start out with very low bone density or many fractures or many women who have failed on a single therapy, this would be a good option if the primary problem was osteoporosis."
The findings aren't entirely new, and a number of women are already using this therapy or a variation of it.
"This confirms other data which have shown improvements in bone density by the combination that is superior to either of the single agents," says Dr. Stephen Honig, director of the Osteoporosis Center at the Hospital for Joint Diseases in New York City. "There's been data out for a couple of years now that show that combination therapy is both safe and effective."
Previous research had found promising results for the combination therapy in younger women. But the effect on older women, who are most at risk for osteoporosis, was unknown. This is the first study to compare the combination therapy with each of the single agents in elderly women.
The Women's Health Initiative (WHI), a long-term study designed partly to assess the risks and benefits of postmenopausal hormone therapy, found an increase in heart attacks, strokes, blood clots and breast cancer in women on hormone replacement therapy (HRT) but a decrease in colorectal cancer and hip fractures. HRT may also decrease the risk for type 2 diabetes.
But there are several differences between the WHI and this study, Greenspan says. "The findings from the WHI included women aged 79 and younger, so older women were excluded and we included them in our study. The other difference is that that study was designed to look at general prevention and ours looked at prevention and treatment for osteoporosis. It was specific."
Osteoporosis is the continuous thinning of bone tissue, making bones more susceptible to fracture. The condition is most common in women over the age of 50, largely a result of reduced estrogen.
According to the National Osteoporosis Foundation, women are four times more likely than men to develop the disease, which currently affects an estimated 10 million Americans. An additional 34 million people are thought to have low bone mass, which puts them in jeopardy of developing osteoporosis.
HRT has a general effect throughout the body. Alendronate has a more specific effect. It sits on top of the bones, where it's absorbed by cells called osteoblasts, which are responsible for eating away at the bone.
"It basically leads to the osteoblasts' early death and blocks them from eating up the bones," says Greenspan, who is also professor of medicine and director of the Osteoporosis Prevention and Treatment Center at the University of Pittsburgh School of Medicine.
The researchers analyzed data on 373 women, 65 to 90 years old, all located in the Boston area. Thirty-four percent of the women had osteoporosis. The rest had osteopenia, or low bone mass, a precursor of osteoporosis.
The women were randomly assigned to receive HRT (with or without progesterone) alone, alendronate alone, both together or neither. All the participants were also given calcium and vitamin D supplements.
Osteoporosis can either be measured by bone density levels or by the number of fractures a person sustains. The researchers opted to study the former, because of the time it would take to look at fractures. Generally speaking, the lower the bone mineral density, the more likely you are to fracture a bone.
After three years, special X-rays called DXA scans revealed that bone mineral density was significantly higher in women treated with the combination therapy than with just one therapy, with mean increases of 5.9 percent at the hip, 10.4 percent at the postero anterior lumbar spine (front view) and 11.8 percent at the lateral lumbar spine (side view).
As always, the choice of a particular therapy is a highly individual one.
"There is no reason to suppose that the risk [of HRT] would differ substantially with the addition of a bisphosphonate [such as aldendronate] to the hormone regimen," the study authors write. "The main results of this study can help answer the question of whether the potential risk of hormone treatment is worth the estimated 8 percent reduction in fracture risk when combination therapy is used compared with alendronate alone."
The study did show the combination was effective and safe in older women with low bone density measures, the researchers add.
Greenspan says doctors will have to weigh the risks and benefits of HRT for each individual patient.
For more on osteoporosis, visit the National Osteoporosis Foundation or the National Institute of Arthritis and Musculoskeletal and Skin Diseases.