Evaluation of Pulmonary Function Tests, Dyspnea Scores, and Antibody Levels at the Six-Month Follow-Up of Patients Hospitalized for COVID-19 Pneumonia

Background: Coronavirus disease 2019 (COVID-19) causes various signs and symptoms, especially lung involvement, during acute infection and in the long term. In this study, we evaluated the follow-up results of patients with chronic COVID-19 over a 24-week period. Methods: The study included a total of 100 post-COVID-19 patients (confirmed by real-time polymerase chain reaction (PCR) of a nasopharyngeal swab) who presented to the post-COVID-19 outpatient clinic with chronic COVID-19 symptoms 12 weeks after diagnosis, between April and June 2021. All of the patients in the study had a history of hospitalization and were grouped based on the severity of the acute COVID-19 infection (moderate: group 1, severe: group 2). Results: A comparison of pulmonary function test parameters at week 12 showed that forced expiratory volume (FEV1)%, forced vital capacity (FVC)%, diffusing capacity of the lungs for carbon monoxide (DLCO)%, and DLCO divided by the alveolar volume (DLCO/VA)% values were significantly lower in group 2 than in group 1 (p<0.001 for all). At week 24, only DLCO and DLCO/VA values were lower (<0.001 for both). The mean modified Medical Research Council (mMRC) dyspnea scores of groups 1 and 2 were 1.4 +/- 0.9 and 2.8 +/- 1.1 at 12 weeks and improved to 0.9 +/- 0.6 and 1.6 +/- 0.6 at 24 weeks, respectively. The groups' mMRC scores at 12 and 24 weeks differed significantly (p=0.001, p=0.02). There was no difference in levels of IgM and IgG antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein between the groups at 12 or 24 weeks (p>0.05 for all). Conclusion: Improvement in pulmonary function parameters and mMRC scores may take longer than 24 weeks, especially in patients with severe COVID-19. Our results indicated that the levels of IgM and IgG neutralizing antibodies did not differ between patients with moderate and severe illness at 12 or 24 weeks.