Determinants of undiagnosed asthma.

Abstract

The conformity between asthma diagnosed in a clinical setting and asthma from an epidemiological point of view has not been much studied. History, symptoms, and clinical findings in persons with and without a previous physician diagnosed asthma were studied among persons classified as having asthma according to an epidemiological definition. Smoking was more prevalent in persons not diagnosed as having asthma prior to the study (n = 96), than in those with a previous asthma diagnosis (n = 119), (60% vs. 41%, P = 0.006). Positive skin prick test (SPT) was less common (39.6% vs. 58.0%, P = 0.009), lung function expressed as FEV1.0 in percentage of predicted was better (92.1 vs. 85.4, P = 0.018), reversibility to a bronchodilator was smaller (mean reversibility 4.0% vs. 6.2% of predicted, P = 0.003) and symptoms were less frequently reported (P < 0.001) by those who had not a physician diagnosed asthma prior to the study. The asthma diagnosis is often overlooked by the medical profession in patients with mild disease. Furthermore, smoking seems to worsen asthma exacerbations in patients with mild disease.