Natural History of Spirometric or Oscillometric Abnormalities in Asymptomatic adults within the general population

<bold>Aims:</bold> To assess the relationship of abnormal spirometry/oscillometry in asymptomatic individuals to the development of respiratory symptoms or disease diagnoses four years later. <bold>Methods:</bold> 2,451 Austrian LEAD study participants (mean age = 48.1±17.1 years, 54% female) without self-reported respiratory symptoms and diagnoses underwent two visits 4.2±0.4 years apart. Subjects were divided according to having normal or abnormal lung mechanics. Normal respiratory mechanics was defined as FVC, FEV1, FEV1/FVC, resistance, reactance (Xrs), inspiratory/expiratory components at 5Hz, and the area above the Xrs curve within the normal limits (GLI and Oostveen et al., 2013) at the first visit. Odds ratios (OR) and 95% confidence intervals (CI) assess the association between abnormal parameters at the first visit and self-reported respiratory conditions at the second. <bold>Results:</bold> Four years later: a) 1,688(68.9%) subjects remained symptom-free, 686(28.0%) reported symptoms, and 77(3.1%) reported being diagnosed with asthma, COPD, or chronic bronchitis. b) Subjects with normal FEV1/FVC (OR=0.53, 95%CI=0.38-0.75), normal Xrs (OR=0.55, 95%CI=0.34-0.87), were more likely to remain symptom-free. c) Subjects with abnormal Xrs (OR=1.60, 95%CI=1.00-2.57) were more likely to develop respiratory symptoms without a doctor’s diagnosed respiratory condition. d) Subjects with abnormal FEV1/FVC (OR=6.19, 95%CI=3.67-10.43) were more likely to report a doctor’s diagnosed respiratory condition. <bold>Conclusions:</bold> Spirometric and oscillometric abnormalities in asymptomatic individuals were associated with an increased risk of developing respiratory symptoms or conditions within four years.