THURSDAY, Feb. 25 (HealthDay News) -- Higher levels of obesity and inactivity, especially among women, explain why arthritis is more common in the United States than in Canada, according to a new study.

Researchers at the Toronto Western Research Institute analyzed 2002-03 data from both countries and found that the prevalence of arthritis in the United States was 18.7 percent and the prevalence of arthritis-attributable activity limitations (AAL) was 9.6 percent. In Canada, the rates were 16.8 percent and 7.7 percent, respectively.

Women in the United States had a higher prevalence of arthritis (23.3 percent) and AAL (13 percent) than Canadian women (19.6 percent and 9.2 percent, respectively). Men in both countries had similar rates of arthritis (14 percent) and AAL (6 percent).

"Our study results suggest that the higher prevalence of arthritis and AAL in the U.S. may be a consequence of greater obesity and physical inactivity in that country, particularly in women," study lead author Elizabeth Badley said in a news release.

"Public health initiatives that promote healthy weight and physical activity may benefit from including arthritis concerns to its message, and could potentially reduce the incidence of arthritis and AAL," she concluded.

The study appears in the March issue of the journal Arthritis Care & Research.

More information

The U.S. Centers for Disease Control and Prevention has more about arthritis.

THURSDAY, Feb. 25 (HealthDay News) -- Women with breast cancer who choose to have a preventive mastectomy on their disease-free breast do reduce their risk of cancer in that breast, studies have shown.

But now new research finds that the survival benefit from that preventive surgery is small and not equal among all women.

"The survival benefit was limited to a small subset of all breast cancer patients [studied]," said study author Dr. Isabelle Bedrosian, an assistant professor of surgical oncology at the University of Texas M.D. Anderson Cancer Center, in Houston.

Those most likely to derive a survival benefit, she said, were those younger than 50 who had been diagnosed with early-stage cancers that were estrogen receptor (ER)-negative.

ER-negative tumors don't require estrogen to grow, as do ER-positive tumors, and the prognosis is poorer for the ER-negative cancers, according to the American Cancer Society.

The study is published online Feb. 25 in the Journal of the National Cancer Institute.

According to Bedrosian and others, experts have long known that women diagnosed with breast cancer have an elevated risk of developing cancer in the opposite breast. Removing that breast as a preventive measure reduces, but does not eliminate, the risk of cancer in that breast.

"But we have never really established the difference it makes in the survival of breast cancer patients," she said. So, Bedrosian and her colleagues used data from the Surveillance, Epidemiology and End Results (SEER) database, evaluating 107,106 women with breast cancer who had undergone mastectomy for that cancer between 1998 and 2003, along with a subset of 8,902 who had the opposite breast removed as a preventive measure.

After a five-year follow-up, 88.5 percent of those who had the opposite breast surgery were alive, versus 83.7 percent of those who did not, a difference of less than 5 percent. The improved survival was clear for a select group, mostly the women aged 18 to 49 with early-stage, ER-negative tumors, the researchers found.

There was no information from the database on whether the women had genetic mutations to boost breast cancer risk, Bedrosian noted.

After five years, what might happen? "We actually would expect that number [the nearly 5 percent benefit] would increase over time," Bedrosian said.

The findings makes sense to Dr. Allison W. Kurian, an assistant professor of medicine at Stanford University School of Medicine in Stanford, Calif., who has published research on the topic.

"These results are consistent with other studies," she said, including her own research published in 2009 in the same journal, which found that the risk for a breast cancer in the opposite breast is affected by a variety of factors, with those having ER-negative tumors in the original breast cancer having a higher risk of getting second tumors in the opposite breast.

Bedrosian said her research suggests most women diagnosed with breast cancer shouldn't be concerned about the opposite breast: "We cannot demonstrate for most of them a survival benefit [with preventive mastectomy on the opposite breast]."

However, she said, psychological factors should also be taken into account. "There are some patients who may feel they still want to do this," she said.

Kurian agreed: "This paper does give more information [about the outlook for various women], but it remains a personal decision for women to discuss with their doctor."

More information

To learn more about breast cancer, visit the American Cancer Society  .

MONDAY, Feb. 22 (HealthDay News) -- Women who experience depression during pregnancy may have another treatment option, new research suggests.

The study found that women treated with depression-specific acupuncture had a 63 percent response rate compared to a 44 percent response rate in women treated with control acupuncture or massage.

"We tested acupuncture as a standalone treatment, and the results are very positive," said study author Rachel Manber, a professor at the Stanford University School of Medicine Sleep Medicine Center in Redwood City, Calif. But, she added, because this is the first study of its kind, and the acupuncture protocol used was specifically designed for this study, "you always need replication of the findings."

Dr. Shari Lusskin, director of reproductive psychiatry at the New York University Langone Medical Center, echoed that sentiment. "It's encouraging to see alternative treatments being studied in a scientific manner, and this study should generate further studies. It needs to be replicated on a larger scale," she noted.

"This is one treatment, and perhaps it will become another possible treatment tool in our therapeutic toolbox," said Lusskin. But, she cautioned that "acupuncture is not a substitute for the appropriate use of antidepressant therapy especially in women with a prior history of response to antidepressants."

As many as 20 percent of women may experience depression during pregnancy, according to the March of Dimes. Symptoms include sad, hopeless feelings that persist, generally for more than two weeks, Lusskin said. Women may also experience severe anxiety or feel disconnected from the baby. And, she cautioned, suicidal thoughts are never normal and are a sign that you should seek help.

Many women are cautious about using medications during pregnancy, reports the study. Interpersonal psychotherapy is an option for women who are depressed during pregnancy, but this type of therapy isn't always available, according to the study.

For the study, Manber and her colleagues recruited 150 pregnant women who were diagnosed with a major depressive disorder. All were between 12 and 30 weeks of gestation.

The women were randomly assigned to one of three groups: depression-specific acupuncture (52 women), control acupuncture (49 women) or massage (49 women). The depression-specific protocol was designed just for this study, and the control acupuncture was specifically designed to avoid using acupuncture needles in any areas known to affect depression.

The treatments lasted for eight weeks. Women received treatment twice a week for the first four weeks, and then once a week for the next four weeks. The treatments lasted an average of 25 minutes.

The researchers found a 63 percent response rate in women who received the depression-specific acupuncture, while the response rate was 44.3 percent in the control acupuncture and massage groups. A response rate was defined as a 50 percent reduction in depression symptoms, Manber said.

Results of the study are scheduled to be published in the March issue of Obstetrics & Gynecology.

"We found our acupuncture protocol was helpful, but that does not mean that any acupuncture for depression treatment will be effective. The quality of what you get can differ from one practitioner to another," said Manber.

"Our goal is always to find treatments that have the maximum benefits and minimum risk," said Lusskin. "Many women think it's safer for the baby to go off antidepressants, but there's a real risk to the baby for untreated depression in pregnancy. And, we have enough safety data about antidepressant use in pregnancy that we can make informed choices about managing treatment during pregnancy."

The bottom line, she said, is to talk with your doctor to find the right combination of treatments that can help you. "Depression is not a one-size-fits-all illness, and treatment won't be one-size-fits-all either. If acupuncture ends up being helpful for you, that's great, but make sure you're treated into remission."

More information

To learn more about depression during and after pregnancy, visit the National Women's Health Information Center.

TUESDAY, Feb. 16 (HealthDay News) -- Using multiple genetic markers to create a risk score for cardiovascular disease doesn't work with women, a new study indicates.

U.S. researchers created genetic marker-based risk scores for 19,313 white women in the Women's Genome Health Study. The genetic risk scores were constructed using the National Human Genome Research Institute's catalog of genome-wide association study results published between 2005 and 2009.

Over a median follow-up of 12.3 years, there were 777 cardiovascular disease events (199 heart attacks, 203 strokes, 63 cardiovascular deaths, 312 coronary artery revascularizations) among the women.

There was no evidence that genetic-based risk scores predicted cardiovascular disease risk. However, a family history of premature heart attack was found to be an independent risk factor for cardiovascular disease, wrote Nina P. Paynter, of Brigham and Women's Hospital in Boston, and colleagues.

The findings "confirm the importance of family history of cardiovascular disease, which integrates shared genetics, shared behaviors and environmental factors," the researchers wrote.

The study is published in the Feb. 17 issue of the Journal of the American Medical Association.

More information

The American Heart Association has more about cardiovascular disease  .