all biostatistics stories

It took a novel tack to discover an obesity gene

404132862 — Wed, 24 Oct 2007 14:23:19 -0400

The racing sailboat was small, and Christoph Lange wanted to be sure he didn't capsize and plunge into the Charles River again, as he'd done half a dozen times that spring. Using his blue sailing shoes for leverage, he carefully arranged himself on the craft's cramped bench and reached for the tiller. The day was mild; the wind barely ruffled the dank water lapping the edges of the ramp that led to the Harvard Sailing Center, in Cambridge, where Lange, assistant professor of biostatistics at the Harvard School of Public Health, had been a member since 2000.

Risk of breast cancer may be associated with red meat consumption

Thu, 12 Jul 2007 09:38:46 -0400

Researchers at Brigham and Women's Hospital (BWH) have found that eating more red meat may be associated with a higher risk for hormone receptor–positive breast cancers in premenopausal women. This research is published in the Nov. 13 issue of the Archives of Internal Medicine.

"This study suggests that dietary factors may be related to a woman's chance of developing this type of breast cancer, a disease that is on the rise in American women," said lead author, Eunyoung Cho, a researcher at BWH.

James Robins makes statistics tell the truth

50443248 — Wed, 18 Jul 2007 13:59:39 -0400

The white board that covers hundreds of feet of the curved hallway at the Institute for Quantitative Social Science (IQSS) is not always covered with equations - but lately, it usually is. And most of them are in the haphazard hand of James M. Robins, an IQSS faculty associate and a professor of epidemiology and biostatistics at the Harvard School of Public Health. "I'm not the most organized person in the world," says Robins, his chair rolling over a splash of papers that spill out of his briefcase and onto the floor of his office. "So the equations usually sit there for awhile before I type them into my computer."

Vitamin D critical to human TB response

70652986 — Mon, 26 Mar 2007 06:25:09 -0400

Vitamin D plays a critical role in the human body's response to tuberculosis, according to new research that explains why people of African descent are more susceptible to TB.

The research also suggests a new way to fight one of the world's deadliest diseases: with a simple dietary supplement.

Tuberculosis, usually caused when a person inhales tuberculosis bacteria, killed an estimated 1.7 million people in 2003 and is the leading cause of death for people afflicted with AIDS, according to the World Health Organization (WHO).

People of African descent are more susceptible to tuberculosis than Caucasians, with higher rates of infection and more severe cases once infected, trends that had puzzled researchers until now. Sub-Saharan Africa, for example, has the world's highest per capita rates of both tuberculosis cases and deaths from the disease, roughly twice the next-highest region, according to WHO statistics.

The research, conducted by a team from the University of California, Los Angeles (UCLA), and the Harvard School of Public Health, shows that vitamin D plays a key role in the production of a molecule called cathelicidin, which kills the tuberculosis bacteria.

The body produces vitamin D when sunlight hits the skin. The skin pigment melanin - more abundant in darker skin - shields the body from the sun's rays, reducing damage from ultraviolet light, but also reducing vitamin D production.

Weight and weight gain may predict breast cancer survival

70652986 — Mon, 26 Mar 2007 06:19:45 -0400

The study included 5,204 women with invasive breast cancer who were between the ages 30 to 55 when enrolled in the study in 1976. The researchers found that women who weighed more before they were diagnosed with breast cancer and those who were lean but gained weight after diagnosis and treatment tended to have worse survival outcomes. Intriguingly, the association was strongest in women who did not smoke.

"By combining smokers and non-smokers in analyses, it may be more difficult to understand the true relationship between weight and survival. This study suggests a more complex relationship between weight and breast cancer survival than was originally considered," said lead researcher Candyce Kroenke, Sc.D., M.P.H., and an instructor at Harvard Medical School.

Among non-smokers, the study showed that overweight women were 1.5 times as likely and obese women two times as likely to die during follow-up than were women with normal BMIs before diagnosis. It also showed that women with substantial weight gain after diagnosis had a more than 50 percent greater risk of death or recurrence than women who maintained their weight after diagnosis. Finally, the strongest link between weight gain and death/recurrence were in pre-menopausal women, those with early stage cancer and those who were lean prior to diagnosis.

Study finds heavy drinking linked to higher stroke risk

70652986 — Mon, 26 Mar 2007 07:09:51 -0400

A study found that while light and moderate drinkers appear to be at neither greater risk nor greater advantage than abstainers when it comes to ischemic stroke, the frequency of their alcohol consumption may modestly influence their risk. The findings reinforce the importance of the volume and frequency of alcohol consumption.

"In this study, the participants who were at lowest risk for stroke were the men who consumed one or two drinks on three to four days of the week," says lead author Kenneth Mukamal, MD, MPH.

Studies find benefit in stop-smoking programs targeted for working-class groups

70652986 — Mon, 26 Mar 2007 05:35:09 -0400

Researchers found that among both whites and blacks, smoking rates are highest among those in working-class, non-supervisory occupations, including blue-collar and service jobs, and those with less education and lower income. In all socioeconomic groups, men were more likely to smoke than women. "Among adults, occupation is a useful category for understanding where the risk of smoking falls heaviest," says the study's lead author, Elizabeth Barbeau of Dana-Farber. "It's clear that smoking is more prevalent among working-class compared to supervisory and professional occupations in all racial and ethnic groups. This finding underscores the need to consider occupational class along with race/ethnicity, gender, education, and income in setting priorities for smoking-cessation programs." Moreover, the researchers found, while smokers in all socioeconomic groups try to quit the habit at about the same rate, people in supervisory and professional occupations, and those with more education and higher incomes, tended to be more able to quit than those with fewer socioeconomic resources. This was true across all racial/ethnic groups and both genders. The findings were published in the Feb. 3, 2004 issue of the American Journal of Public Health.

Smoking increases bleeding into the brain, study finds

70652986 — Mon, 26 Mar 2007 05:34:11 -0400

A research team at Brigham and Women's Hospital (BWH) found that stroke risk for women increased proportionately with the number of cigarettes smoked each day. In contrast, women who stopped smoking were at no additional risk. The findings appeared in the Nov. 13, 2003 online edition of the journal, Stroke, a publication of the American Heart Association.

Study finds frequent consumption of alcohol linked to lower risk of heart attack in men

70652986 — Mon, 26 Mar 2007 05:27:29 -0400

Men who drank moderate amounts of alcoholic beverages three or more times a week had a risk of myocardial infarction 30 to 35 percent lower than nondrinkers. The observational study, which tracked the drinking habits of nearly 40,000 men over a 12-year period, provides an important clue as to how alcohol helps guard against coronary heart disease, and for the first time, strongly suggests that routine consumption of alcoholic beverages is key. "Even relatively modest amounts of alcohol may be protective if consumed frequently,” said the study's first author, Kenneth Mukamal, of Beth Israel Deaconess Medical Center's Division of General Medicine and Primary Care and assistant professor of medicine at Harvard Medical School. “Our results document that a pattern of regular consumption at least three to four days per week is associated with the lowest risk of heart attacks.” The findings appeared in the Jan. 9, 2003, issue of The New England Journal of Medicine. This research was funded by grants from the National Institutes of Health.

Study predicts risk of prostate cancer death

70652986 — Mon, 26 Mar 2007 05:26:18 -0400

Researchers followed 381 people to "identify predictors of time to prostate specific death following external radiation therapy." "The results of this study give us a better understanding of what form of treatment will extend a patient's life to a point where he's more likely to die from causes other than prostate cancer," says Anthony D'Amico, research leader and an associate professor of radiation oncology at Harvard Medical School. He and his colleagues divided the men into three groups: high, intermediate, and low risk of prostate cancer death. The first thing they checked was the amount of PSA, or prostate-specific antigen, in the men's blood. The body secretes excess amounts of this protein in response to prostate cancer. The higher its level, the more cancer is present.

Studies find milk consumption, use of HRT, and pregnancy may influence hormone levels associated with cancer risk in women

70652986 — Mon, 26 Mar 2007 05:24:49 -0400

IGF-1 is a hormone important to the growth and function of many organs. Higher levels of IGF-1 have been associated independently with an increased risk of a number of cancers, including prostate, colon, lung and breast cancer. Two studies examined the relationship between modifiable lifestyle factors and circulation levels of IGF-1 to potentially define new methods of cancer prevention. Women with four or more pregnancies had IGF-1 levels that were on average 15 percent lower than in women who had no history of pregnancy. "Our most important new finding is that there is an inverse association of circulating IGF-1 levels with increasing parity in healthy women," said researcher Michelle Holmes. "This association may define one way in which pregnancy exerts a protective influence on cancer, reducing risk in women." A second related study examined how diet affects IGF levels in well-nourished individuals. The most consistent finding was a positive association between protein with circulating IGF-1 concentrations, largely attributable to milk intake. "We concluded that greater milk consumption was associated with higher levels of IGF-1," said Holmes.

Statistical work helps calm worries about anti-AIDS drugs and pregnancy

70652986 — Mon, 26 Mar 2007 05:22:15 -0400

For years, physicians have prescribed antiretroviral therapies for HIV-positive, pregnant women to reduce the risk of babies being born with the AIDS virus. About 6,000 HIV-infected women give birth each year in the United States, according to the Centers for Disease Control. Concerns about the effects of anti-AIDS drugs and premature births were raised by the contemporaneous release of results from a study in Switzerland and the observation of an unexpectedly large number of premature births in three ongoing Phase I clinical trials of combination antiretroviral therapy in the United States.

Biostatisticians crunch data vital to AIDS research, genetics

70652986 — Mon, 26 Mar 2007 05:18:17 -0400

Broadly defined, statistical genetics is the development of methods to analyze DNA. In recent years, the term has been more specifically applied to gene mapping, or the search for locations of genes related to diseases, and to the analysis of drug therapies. Statistical genetics plays a significant role in what some experts predict to be the future of pharmaceutical therapy -- individualized medicine. "The idea is that you would monitor a patient regularly to gain a sense of when a drug treatment has become ineffective," explained Stephen Lagakos, chair of the Department of Biostatistics at the Harvard School of Public Health.

Study shows obesity can increase risk of pancreatic cancer

70652986 — Mon, 26 Mar 2007 07:09:30 -0400

Each year almost 30,000 people in the United States are diagnosed with pancreatic cancer. About the same number of people are killed by it. Pancreatic cancer is the fifth-leading cause of cancer-related deaths in the U.S. A study by researchers at Brigham and Women's Hospital (BWH), the Harvard School of Public Health (HSPH) and Dana-Farber Cancer Institute found that people who are significantly overweight and engage in little physical activity have a substantially higher risk of developing pancreatic cancer. Researchers found that people classified as obese were 72 percent more likely to develop pancreatic cancer than people of normal weight. They also found that men and women who walk or hike four or more hours per week had a 50 percent lower risk of pancreatic cancer than those who exercise less than 20 minutes per week. Researchers add that this research should promote insights into the basic causes of pancreatic cancer. A better understanding of the causes of pancreatic cancer could provide better therapeutic approaches to the disease.

Testing to identify drug-resistant AIDS strains is cost-effective

70652986 — Mon, 26 Mar 2007 05:05:38 -0400

A new study led by the Harvard Center for Risk Analysis, published in the Annals of Internal Medicine in March 2001, finds that testing people with HIV to determine whether they have a drug-resistant strain of the virus is a cost-effective use of resources in the battle against HIV. In fact, the study finds that investing in this genetic resistance testing is approximately as cost-effective as the money spent on the drug therapy itself. Despite significant gains in treating people with HIV, antiretroviral drug therapy initially fails in nearly half of those patients. A common reason is that the virus develops resistance to some of the drug being used. Genetic testing to identify strains of the virus that are drug resistant can help clinicians adjust the "AIDS cocktail" mix of drugs so therapy is more effective.