Laboratory investigations
Nasopharyngeal swabs were obtained at admission and COVID-19 infection was diagnosed with real time reverse-transcription PCR using Coronex COVID-19 rt-qPCR detection kit (Gensutek, Turkey). For all other tests, blood samples were obtained immediately after the diagnosis of COVID-19 was ascertained with a positive PCR test and a thorax CT scan compatible with COVID-19 pneumonia. Interleukin-6 concentration was determined with electrochemiluminescence immunoassay method, using Elecsys IL-6 biochemical analysis kits and Roche Cobas 6000 analysis device (Roche Diagnostics, Basel, Switzerland). Other laboratory analyses were done with conventional methods.