Study Population
This study was approved by both the Scientific Committee of our hospital and the Ministry of Health COVID-19 Scientific Research Evaluation Committee date/number 04.05.2020 /3801.
All patients who were hospitalized in our Chest Diseases Training and Research Hospital between 11 March 2020 and 1 October 2020 diagnosed with confirmed or probable COVID-19 pneumonia were included in this retrospective, non-interventional, single-center case-cohort study. All patients who were hospitalized for COVID-19 pneumonia underwent Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) nasopharyngeal swab test for SARS-CoV-2 virus. A positive result in the RT-PCR test of nasal and pharyngeal swab samples was considered to be a laboratory-confirmed patient. Also, patients who had negative RT-PCR but positive antibody tests and clinical and radiological signs compatible with COVID-19 pneumonia were included in the study. The diagnostic criteria, method, and severity of the disease were evaluated according to the Scientific Committee Guidelines of the Ministry of Health (7).