SAN ANTONIO – A diagnosis of asthma, allergic disease, or obstructive or restrictive lung disease among participants in the first National Health and Nutrition Examination Survey conferred a significantly increased long-term risk of all-cause mortality for adults who were aged 40-75 years at baseline but not for those who were aged 25-39 years at baseline, according to findings from the study.
A diagnosis of asthma in the younger group conferred an increased long-term risk of death due to respiratory causes – as did a diagnosis of asthma in the older group, Dr. Jessica R. Savage reported in a poster at the annual meeting of the American Academy of Allergy, Asthma, and Immunology.
"This association was not likely explained by underlying bronchitis or an increased risk of death due to respiratory infection but was likely due to asthma itself," said Dr. Savage of Brigham and Women’s Hospital, Boston.
"I think the main conclusions are reassuring – no increase in mortality if you are young and have allergies. Some studies show an association between allergy and stroke/heart disease. We were worried that with the rising increase in allergy, there would be also an increase in these other diseases. But we did not see that, fortunately.
"We saw an association with asthma and respiratory death even in the young. Of course, one always needs to remember to be vigilant with asthmatics, but overall for young people the news is good," she said during an interview.
Data were obtained from the National Health and Nutrition Examination Survey (NHANES I), which was conducted from 1971 to 1975 and included 31,937 adults. Of these participants, 14,407 were included in the NHANES I Epidemiologic Follow-Up Study (NHEFS) and were assessed for doctor-diagnosed asthma, allergic rhinitis, food allergy, and urticaria. A subcohort of 6,913 subjects received a more detailed health interview and examination, including prebronchodilator spirometry and percent predicted forced expiratory volume and forced vital capacity. Vital status and cause of death were obtained in 2006.
After adjustment for age, gender, income, education, race, and smoking history, a sensitivity analysis for the association between asthma and mortality demonstrated a significantly increased long-term risk of death in those who were aged 40-75 years at baseline (hazard ratio, 1.22), but not for those aged 25-29 years at baseline (HR, 1.20). The hazard ratios for all-cause mortality in these groups, after exclusion of subjects with bronchitis were not statistically significant (1.16 and 1.52, respectively).
Hazard ratios for the association between asthma and respiratory mortality were significant at 2.03 and 5.87 for the older and younger groups, respectively. The hazard ratios for these groups remained statistically significant at 8.56 and 1.82, respectively, after exclusion of subjects with bronchitis.
This study also demonstrated that older subjects with obstructive lung disease were at significantly increased risk of both all-cause and respiratory mortality and that older subjects with restrictive lung disease were at significantly increased risk of both all-cause and cardiovascular mortality.
Conversely, older adults with urticaria had a reduced risk of cardiovascular mortality.
Cancer-related mortality was slightly, but not significantly, increased in the younger subjects diagnosed with urticaria, and in the older subjects diagnosed with asthma or moderate to severe lung obstruction.
"Asthma and allergic diseases, which typically manifest in childhood, have increased in the United States over the last 3 decades. Asthma and allergy may increase mortality by directly reducing lung function or may be markers of immune dysregulation that could lead to systemic inflammation," Dr. Savage noted, adding that although prior studies have demonstrated associations between allergic sensitization and stroke, hives and cancer, asthma and mortality, and obstructive lung disease and cardiovascular events, the effects of asthma and allergic disease on long-term mortality have been unclear.
"The findings (of this follow-up study) provide some insight regarding the effects of asthma and allergic disease on long-term mortality, Dr. Savage said.
The NHEFS is a joint project of the National Center for Health Statistics and the National Institute on Aging in collaboration with other agencies of the U.S. Public Health Service. Dr. Savage reported having no disclosures.