Obesity May Be Linked to Adult-Onset Asthma in Women
Dec. 1, 1999 (New York) -- Have researchers uncovered yet one more reason to
lose weight? According to a report in the Nov. 22 Archives of Internal
Medicine, investigators have found a link between high body mass index in
women and an increased risk of developing adult-onset asthma.
The association is strongest using the most stringent criteria for
diagnosing asthma, the study's lead researcher tells WebMD. But some
commentators say that the association may not be strong enough for physicians
to act upon, and, as is typical in the field of research, they say more studies
are needed to confirm the findings.
The study is yet one more piece of data showing that asthma is more
prevalent in populations where obesity is widespread, according to Carlos A.
Camargo Jr., MD, who led the study. Researchers analyzed data from the Nurses'
Health Study, a study of female U.S. registered nurses between the ages of 25
and 46. The Nurses' Health Study permits analysis of a wide variety of
variables and has been used for years to assess risk factors for a variety of
Camargo, an assistant professor of medicine at Harvard Medical School, tells
WebMD that the analysis used high-quality techniques to eliminate the
possibility that other variables -- such as smoking, physical activity, or race
-- might be the more likely explanation for their finding.
Analyzing data on nearly 86,000 nurses, the researchers found that "body
mass index had a strong, independent, and positive association with the risk of
developing adult-onset asthma," says Camargo. Body mass index (BMI) is a
measurement of weight related to height.
He also points out that in many of the communities where asthma is prevalent
in children, such as the South Bronx and Harlem, those same children are often
overweight. He says that new data will show the association that his group
found in other populations. It will also demonstrate a link between obesity and
inflammation, perhaps the most widely recognized mechanism that causes
But experts tell WebMD that while the results are provocative, there is a
question whether obesity really is a major culprit for adult-onset asthma.
There is also question over whether weight control for asthmatics should be
embraced as a key prevention strategy.
"In a study like the Nurses' Health Study, there are more than 900
variables," says Albert Wu, MD, MPH, in an interview seeking objective
commentary on the study. "There are many, many predictive variables and
there is the possibility of a spurious association." Wu is associate
professor of healthy policy and management and medicine at Johns Hopkins
University in Baltimore.
Before recommending weight loss as a strategy to prevent adult-onset asthma,
Wu tells WebMD that "the finding needs to be replicated in a study intended
to answer the question." In the Nurses' Health Study, Wu says, "there
are so many potential associations that there is always the risk of chance, and
that it is not a true association." Because the Nurses' Health Study has
such a "large number of candidate variables and an equally large number of
disease and other health outcomes," he says, "that a finding like this
deserves to be replicated."