Longitudinal changes in abnormal lung mechanics in a general population

<bold>Background:</bold> Longitudinal performance of oscillometry data compared to traditional spirometry in a general population is missing. <bold>Aims:</bold> to observe changes in abnormal lung mechanics according to spirometry and oscillometry in an observational general population. <bold>Methods:</bold> 2279 subjects of the Austrian LEAD study (mean age=48.7y, females=54%) underwent oscillometry and spirometry measures 4.3±0.2 years apart. The z-score of resistance and reactance (X) at 5 Hz, their inspiratory and expiratory components, and the area above the X curve were computed. Any abnormal parameter or the presence of tidal expiratory flow limitation identified abnormal oscillometry. Abnormal spirometry was defined as the z-score of the forced vital capacity, the forced expiratory volume in the first second, or their ratio < - 1.64. <bold>Results:</bold> 74.3% of subjects remained in the same category (Figure). <fig><object-id>erj;64/suppl_68/PA3055/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig> In 11.3% and 3.0% of subjects, oscillometry and spirometry become abnormal, respectively. In 1% of subjects, both oscillometry and spirometry became abnormal. 5.0% and 4.0% of subjects with impaired oscillometry and spirometry became normal, respectively. In 0.8 % of subjects, both oscillometry and spirometry became normal. 0.2% had only abnormal oscillometry at the first measure and only abnormal spirometry 4 years later. The opposite happened in 0.5% of subjects. <bold>Conclusions:</bold> Classification of subjects according to lung mechanics was consistent in most subjects.