The changes of pulmonary function parameters due to COVID-19 in patients with chronic pulmonary diseases: follow-up after COVID-19

Abstract

A little was known about changes in lung function after COVID-19. The most studies did not report the previous lung function of the patients, so it is not possible to know the real effect by the infection. The aim of study was to compare the changes of pulmonary function parameters before and after COVID-19 in patients with chronic pulmonary diseases. Materials and methods. 64 survivors after COVID-19 (aged 54.6±13.6) with chronic pulmonary diseases who had pulmonary function tests before COVID-19 have undergone pulmonary function testings after the disease (77±79 before and 35±32 weeks after COVID-19). We evaluated Cohen`s effect size [ES] (the difference of mean values divided by the standard deviation of baseline score) of parameters of pulmonary function and compared their changes. Results. Forced vital capacity (FVC) was 103.6±19.6 and 95.7±22.0% of projected values; (p<0.001); forced expiratory volume in one second (FEV1) was 96.0±20.5 and 87.1±22.7% of projected values (p<0.001); total lung capacity (TLC) was 102.2±16.0 and 99.0±21.6% of projected values (p<0.084); diffusing capacity (DLco) was 74.0±16.3 and 63.5±18.0% of projected values (p<0.001); before and after COVID-19, respectively. ES for FEV1, FVC, TLC, and DLco were minus 0.26, 0.22, 0.21 and 0.4 respectively. The biggest ES was for DLco after severe COVID-19 (1.81). Conclusion. After COVID-19, patients with chronic lung diseases had a decrease in pulmonary function parameters, the largest changes were observed in diffusion capacity, especially after severe COVID-19.