CHRONIC RESPIRATORY SYMPTOMS AND AIRWAY RESPONSIVENESS TO METHACHOLINE ARE ASSOCIATED WITH EOSINOPHILIA IN OLDER MEN - THE NORMATIVE AGING STUDY

Identification of subsets of patients with chronic obstructive lung disease (COLD) in order to determine disease outcomes and, possibly, the effects of treatment is an area of clinical interest. At present, it remains unclear which patients with COLD are most likely to benefit from anti-inflammatory therapy, We investigated this question in a community-dwelling sample of men. In this study, the relationship of chronic respiratory symptoms, airway responsiveness to methacholine, and skin test reactivity to peripheral-blood eosinophil and neutrophil counts was examined among 894 male participants in the Normative Aging Study (mean age 60 yrs; range 41-90 yrs), The symptoms considered were asthma, persistent wheeze, dyspnoea, chronic cough and phlegm, Responsiveness to methacholine was defined as a provocative dose producing a 20 % fall in forced expiratory volume in one second (PD(20)FEV(1)) of less than or equal to 8.6 mu mol, a positive skin test as a wheal diameter of greater than or equal to 5 mm after subtraction of the diameter of any wheal reaction to a glycerin control, and eosinophilia as an eosinophil count of greater than or equal to 275 cells . mm(-3) in peripheral blood. Chronic symptoms (odds ratio (OR) 2.0; 95 % confidence interval (CI) 1.4-2.7), airway responsiveness (OR 1.7; CI 1.1-2.7), and the combination of symptoms and airway responsiveness (OR 3.4; CI 2.0-5.6) were positively and significantly related to peripheral-blood eosinophil counts, These relationships remained significant after adjustment for the effects of age and smoking, and after exclusion of asthmatic subjects, Symptoms and airway responsiveness combined were not significantly related to neutrophil counts. These data suggest that increased airway responsiveness to methacholine is associated with elevated peripheral-blood eosinophil counts in subjects with chronic respiratory symptoms, Asymptomatic subjects with increased airway responsiveness also have increases in peripheral-blood eosinophil counts.