Older patients with asthma have a greater proportion of eosinophilic airway inflammation compared with younger patients and this may explain their higher mortality rates, according to study results presented at the American Thoracic Society 2012 International Conference in San Francisco.
Researchers in Canada conducted a retrospective, 6-year analysis of 1,046 patients diagnosed with asthma, including patients (n=930) younger than 65 years and patients (n=116) aged 65 years and older. Induced sputum cell counts were taken from all patients, and the patients were categorized into four inflammatory types: eosinophilic (>2.0% eosinophil count), neutrophilic (>64.4% eosinophil count), mixed granulocytic (eosinophils and neutrophils), and pauci-granulocytic.
Seventy-five percent of the patients 65 and older (54% eosinophilic, 21% mixed granulocytic) had sputum eosinophils greater than 2% compared with 54% of the younger patients (38% eosinophilic, 15% mixed granulocytic) (P<.001). Median eosinophil count in the older group was 7% compared with 2% in the younger group (P<.001). Neutrophil counts were statistically insignificant between the groups, while the older group displayed more severe airflow obstruction than the younger group (forced expiratory volume in 1 second [FEV1] 75% vs. 85%) (P<.001).
“Asthmatic patients over the age of 65 have a higher proportion of eosinophilic airway inflammation when compared to younger patients,” the researchers wrote. “These results indicate that the asthma in the elderly is unlikely to be due to misclassification of COPD, and implies that elderly patients are either less adherent to current asthma therapies or that the underlying airway inflammation is relatively resistant to current anti-inflammatory therapies.”
For more information: Leigh R. Abstract #27261. Presented at: The American Thoracic Society, 2012 International Conference, May 18-23, San Francisco.