Smoking and airway hyperresponsiveness especially in the presence of bloodeosinophilia increase the risk to develop respiratory symptoms - A 25-yearfollow-up study in the general adult population

Airway hyperresponsiveness (AHR) constitutes a risk for development of resp iratory symptoms. We assessed whether blood eosinophilia (greater than or e qual to 275 eosinophils/mu l), skin test positivity (sum score greater than or equal to 3) and cigarette smoking (never, ex-smoker, 1-14 cig/d, 15-24 cig/d, greater than or equal to 25 cig/d) at the first of two successive su rveys are related to the development of respiratory symptoms (chronic cough or phlegm, bronchitis, persistent wheeze, dyspnea, and asthma) at the seco nd survey, and whether these relations are the same in subjects with (PC10 less than or equal to 8 mg/ml histamine) and without AHR. We analyzed data of the longitudinal Vlagtwedde-Vlaardingen Study (1965 to 1990) using logis tic regression analyses with paired observations, taking multiple measureme nts within a person into account. In total, 995 men and 792 women contribut ed 4,403 paired observations. Eosinophilia in hyperresponsive subjects sign ificantly increased the risk to develop one or more respiratory symptoms (o dds ratio [OR] = 3.67, 95% confidence interval [CI] = 1.79 to 7.52), wheeze (OR = 5.06, 95% CI = 2.11 to 12.13), and dyspnea (OR = 2.73, 95% CI = 1.13 to 6.60), independent of smoking, age, sex, area of residence, and time be tween two successive surveys. Smoking at the first of two successive survey s increased the risk to develop symptoms in a dose-dependent relation. Subj ects with positive skin tests in the past were less likely to develop one o r more respiratory symptoms (OR = 0.64, 95% CI = 0.46 to 0.88) and chronic phlegm (OR = 0.65, 95% Cl = 0.42 to 1.00), independent of AHR. This longitu dinal study in the general adult population shows that cigarette smoking an d hyperresponsive subjects are at increased risk to develop respiratory sym ptoms, and especially so when eosinophilia is present in hyperresponsive pe rsons.