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).