Pollution and obesity impact asthma control in seniors
By Eddy Ball
A new study, funded in part by NIEHS, explores the effects of traffic pollution and obesity on the growing number of asthmatics in the U.S. who are 65 or older. The paper appears in the June issue of the Annals of Allergy, Asthma, and Immunology.
Despite the public health implications of the high rates of morbidity and nearly five-times greater asthma-related mortality in this population, the researchers wrote, predictors of asthma control in older people remain poorly understood. To the researchers’ knowledge, theirs is the first study to demonstrate a significant association between estimated daily residential exposure to diesel particulate matter and asthma severity in people 65 and older, who make up two-thirds of asthma-related deaths each year.
"Poor asthma control can lead to a decreased quality of life and an increased risk for emergency department visits, hospitalizations, and death,” lead author Tolly Epstein, M.D., was quoted as saying in a University of Cincinnati (UC) press release. Epstein is an assistant professor in the division of immunology, allergy, and rheumatology in UC’s Department of Internal Medicine and a UC Health allergist who headed the team of eight clinicians and environmental scientists.
A growing public health issue
"The health effect of outdoor air pollutants on asthma in baby boomers, as well as young children, is substantial and underappreciated,” said study co-author David Bernstein, M.D., a professor in the UC immunology, allergy, and rheumatology division and also a UC Health allergist.
According to the study’s authors, this population, with an asthma prevalence rate as high as ten percent, is currently estimated to include 3.1 million people and is expected to double within the next 25 years. Seniors typically experience higher rates of obesity as well, which the study found was also associated with poorer asthma control. In addition, obesity may have exacerbated host responses to traffic pollution for people with asthma. Reasons for this are unclear, but could possibly be due to weight-related inflammation. The researchers speculated that an age-related decline in antioxidant defenses may explain why older asthmatics are especially susceptible to the effects of such air pollutants as nitrogen dioxide, ozone, and fine particulate matter.
Asthmatic seniors in Cincinnati
The researchers, all of whom have experience with similar studies involving children, carefully controlled the selection and study of their population of 104 patients, 65 years or older, who were recruited from allergy and clinical programs in the greater Cincinnati area. Enrollment required a physician’s diagnosis of asthma as well as independent clinical confirmation based on objective testing. The team excluded patients with chronic obstructive pulmonary disease or congestive heart failure.
The participants completed a standardized, close-ended demographics and medical questionnaire, which was verified with medical records, and the Asthma Control Questionnaire (ACQ), which was used to quantify symptom severity. The team estimated daily exposure to elemental carbon attributable to traffic (ECAT) using a land-use regression model based on the participant’s current residential address.
Analysis showed that participants exposed to higher levels of ECAT were nearly three times more likely to have higher ACQ scores, indicating more severe symptoms. Obese participants, defined as those with a body mass index greater than 30, were more than five times as likely to have higher ACQ scores.
The NIEHS-funded UC Center for Environmental Genetics and a U.S. Public Health Service grant provided support for the study. The university’s NIH-funded Center for Clinical and Translational Science and Training made a Mentored Clinical Scientist Development Program Award to Epstein for this research.
Citation: Epstein TG, Ryan PH, LeMasters GK, Bernstein CK, Levin LS, Bernstein JA, Villareal MS, Bernstein DI. 2012. Poor asthma control and exposure to traffic pollutants and obesity in older adults. Ann Allergy Asthma Immunol 108(6):423-428.