New findings presented at a press panel of the ATS2000 meeting here today include a new study showing high levels of asthma-triggering allergens in U.S. homes, a study revealing almost six in 10 Canadians with asthma do not have their disease under control, and a possible link between living in high-crime areas and the development of asthma. ATS2000 is the American Thoracic Society's 96th International Conference.
High Levels of Asthma-Triggering Allergens in U.S. Homes A significant portion of U.S. homes have beds with dust mite and cockroach allergen levels that exceed levels previously associated with triggering asthma symptoms, a U.S. government researcher reported today at the ATS2000 press panel.
Researchers from the U.S. National Institute of Environmental Health Sciences conducted the National Allergen Survey to determine the types and levels of allergen in floor and bed dust in U.S. housing, in light of recent evidence that cumulative exposure to indoor allergens is a risk factor for developing allergic disease and asthma. In addition, high levels of indoor allergens have been found to increase the severity of asthma.
The study included 831 homes representative of the nation's regions, ethnicity, socioeconomic status and housing characteristics. In each home, researchers collected vacuumed dust in five or six sites, and questioned home owners about such issues as how frequently the home was cleaned, and whether occupants had allergies or asthma. Extrapolating the findings to the entire U.S. housing stock, the researchers estimated that 44 million homes (over 45% of occupied housing units) have beds with levels of dust mite previously associated with allergen sensitization, while 22 million homes (23%) are estimated to have beds with levels of dust mites believed to be associated with symptomatic asthma. Patrick J. Vojta, Ph.D., lead researcher, reported that only 4% of homes report using impermeable mattress/pillow covers on their beds, a recommended method to help cut down on dust mite exposure.
The study also found that 4% of homes are estimated to have beds with levels of cockroach allergen believed to be associated with allergen sensitization. Less than 40% of American households wash their bedding at least weekly in hot water, the survey found.
For a person with asthma or allergies who is trying to lower their exposure to indoor allergens, says Dr. Vojta, there are a number of steps that people can take to attempt to reduce their exposure to these allergens:
1)encase mattress and pillows in dust-proof or allergen impermeable covers; wash all washable bedding and blankets once a week in hot
water (at least 130-140 degrees F) to kill dust mites;
2)replace wool or feathered bedding with synthetic materials and traditional
stuffed animals with washable ones;
3)if possible, replace wall-to-wall carpets in bedroom with bare floors (linoleum, tile or
wood);
4)use a damp mop to remove dust (never use a dry cloth since this just stirs up mite allergens);
5)use a dehumidifier or air conditioner to maintain relative humidity at about 50% or lower; and
6)use a vacuum cleaner with low emissions (double-layered microfilter bag or a HEPA filter to trap allergens that pass through a vacuum's exhaust).
Many Canadian Asthmatics Don't Have Disease Under Control
Almost six in 10 Canadians with asthma do not have their disease under control, yet 85% say their asthma is being "adequately" or "very well" controlled, according to a study presented at the ATS2000 press panel today. The researchers from the University of Toronto and McGill University found that many patients underestimate the severity of their condition, and have lower expectations than their doctors about how well their asthma can be controlled. Kenneth R. Chapman, M.D., lead author, noted that this is a problem for patients because poor asthma control is associated with impaired quality of life, as well as increased use of healthcare resources.
The researchers questioned 799 adults with asthma and 202 parents of children with asthma, and found that 57% failed to achieve acceptable levels of asthma control. Of these poorly controlled asthma patients, 34% had been absent from school or work or missed social engagements in the 3 months before the survey and 60% limited their physical activities because of asthma, yet 85% regarded their asthma as being "adequately" or "very well" controlled.
The study also revealed that many patients did not understand the role of their medications, a lack of understanding that leads to misuse of their asthma drugs. "The findings are disheartening. Not only are patients not telling their doctors about their asthma symptoms, but doctors must be failing to question patients adequately about their asthma symptoms," said Dr. Chapman, Professor of Medicine at the University of Toronto. "Often, the doctor asks, 'How's your asthma doing?' and the patient says, 'OK,' and that's as far as the encounter goes," Dr. Chapman said. "Doctors need to ask more specific questions."
The researchers also surveyed 266 physicians. Of physicians surveyed, 90% of respirologists and 77% of family or general practitioners felt that they are obtaining optimal control of their patients with asthma. "We conclude that low patient expectations lead to a widespread problem of poorly controlled asthma," Dr. Chapman noted. He added that these study results are similar to those found in a recent survey of U.S. patients, and another study of asthma patients in seven European nations.
Asthma and Violence
Children under the age of 26 months who live in areas with higher levels of violent crime are up to twice as likely to have physician-diagnosed asthma as those who live in low-crime areas, according to a study by Harvard University researchers presented at the ATS2000 press panel today. In addition, this study suggests violent crime and higher levels of vacant housing was each associated with a 40% increased risk of having physician-diagnosed asthma among children over age 2.
Lead researcher Rosalind Wright, M.D., M.P.H., says that the disproportionate asthma burden among urban minority children may be partly explained by differential exposure to life stress. "Evolving evidence suggests that the health of individuals is affected not only by their personal characteristics, but also by the social environments in which they live," she said. "If people are so stressed about their lives, they may not have time to learn about their asthma, and they may not place a high priority on controlling their disease. They may not have control over aspects of their living conditions, such as cockroach infestation of their apartment building. And there is a lot of good evidence that stress affects the body directly, by impacting the immune system."
She and colleagues set out to find out whether living in areas of social disorganization (defined by measures including poverty, substandard housing, and high rates of crime and violence), might worsen the impact of individual-level risk factors of asthma. They interviewed the families, used the Boston police database to calculate violent crimes reported per capita, and used census data to look at poverty and housing. They examined the relationship between markers of neighborhood disadvantage and data on 549 inner-city children they had followed since birth for development of asthma/wheeze, looking at incidence of these children's respiratory symptoms, use of bronchodilators, and physician diagnosis of asthma.
Dr. Wright presented data on this same group of children at the ATS meeting two years ago suggesting that violence may be associated with increased severity and occurrence of asthma among inner-city children. That earlier study suggested that children exposed to violence in their neighborhood (such as hearing gunshots, or witnessing physical violence, often involving weapons), were twice as likely to experience wheezing and to use bronchodilator asthma medication for wheezing, and almost three times as likely to be diagnosed with asthma compared with children not exposed to violence.
"We have now been able to measure this both at the individual level, in our earlier study, and at the community level, in this new study," Dr. Wright said. "This information has the potential to help us understand the disproportionate burden of asthma in economically disadvantaged communities."