MATERIALS AND METHODS
Patients hospitalized with diagnosis of Covid-19 between October 2 and December 25, 2020were enrolled. The diagnosis of Covid-19 was confirmed with at least one positive real-time reverse transcriptase-polymerase chain reaction (RT-PCR) test result in cases admitted with symptoms, signs and findings (laboratory/radiological) suggestive of Covid-19, according to the national guidelines [13]. We excluded the following patients; patients who were on regular hemodialysis, pregnant, who were transferred from intensive care unit (ICU), who had urinary tract infection or who had uretheral catheters. For patients who had multiple qualifying hospital admissions, we included only the first hospitalization however outcomes were recorded according to the last hospitalization.
The source of medical records was OCTOMED (Kartal Dr.Lutfi Kirdar City Hospital Automation Program) electronic database system. The National Public Health Data Management System database was also used as an external data source, particularly to track the RT-PCR test results and to obtain data on previous creatinine values. We collected data for patient demographics, comorbidities, vital signs and laboratory test results on admission. Laboratory data consisted of measurements of white blood cell (WBC), lymphocyte, hemoglobin (Hb), platelet count (PLT), serum glucose, urea, creatinine (SCr), albumin, sodium, potassium, chloride, calcium, aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), C-reactive protein (CRP), ferritin, fibrinogen, D-dimer and creatinine kinase (CK) levels.The first value of laboratory data within 48 hours of hospital admission was taken. Additionally, peak and discharge creatinine values were also collected. IL-6 was taken once as the highest value during hospitalization. Furthermore, medications used for the treatment of Covid-19 were also recorded.
We additionally collected urinalysis with automated microscopy that were obtained within 48 hours after admission. The urine samples were collected in containers, transported and analysed within 2 h of collection. The analyses were carried out on H-800 and FUS-200 automatic modular urine analysers (Dirui Industry, Changchun, China). A further microscopic analysis of sediments was performed, if required.
Outcomes data were retrieved until January 10, 2020. By the time of this analysis, all patients had either died or had been discharged from the hospital. The primary outcome was the development of AKI and secondary outcome was in-hospital mortality.