1 . WHO "Coronavirus (COVID-19) Dashboard | WHO Coronavirus (COVID-19) Dashboard With Vaccination Data" . Available from: https://covid19.who.int.

2 . "Mortality Analyses - Johns Hopkins Coronavirus Resource Center" . Available from: https://coronavirus.jhu.edu/data/mortality.

3 . Goel S, Jain T, Hooda A, Malhotra R, Johal G, Masoomi R, et al.. "Clinical Characteristics and In-Hospital Mortality for COVID-19 Across The Globe" . Cardiol Ther. 2020Dec 1; 9(2):553–9.

4 . Zhou F, Yu T, Du R, Fan G, Liu Y, Liu Z, et al.. "Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study" . Lancet (London, England). 2020Mar 28; 395(10229):1054–62.

5 . Arentz M, Yim E, Klaff L, Lokhandwala S, Riedo FX, Chong M, et al.. "Characteristics and Outcomes of 21 Critically Ill Patients With COVID-19 in Washington State" . JAMA. 2020Apr 28; 323(16):1612–4.

6 . Quah P, Li A, Phua J, Phua J. "Mortality rates of patients with COVID-19 in the intensive care unit: A systematic review of the emerging literature" . Crit Care. 2020Jun 4; 24(1):285.

7 . Zimmerman JE, Kramer AA, McNair DS, Malila FM. "Acute Physiology and Chronic Health Evaluation (APACHE) IV: hospital mortality assessment for today's critically ill patients" . Crit Care Med. 2006; 34(5):1297–310.

8 . Vincent JL, Moreno R. "Clinical review: Scoring systems in the critically ill" . Crit Care. 2010Mar 26; 14(2):1–9.

9 . Gall JR, Lemeshow S, Saulnier F. "A New Simplified Acute Physiology Score (SAPS II) Based on a European/North American Multicenter Study" . JAMA. 1993Dec 22; 270(24):2957–63.

10 . Knaus WA, Zimmerman JE, Wagner DP, Draper EA, Lawrence DE. "APACHE-acute physiology and chronic health evaluation: a physiologically based classification system" . Crit Care Med. 1981; 9(8):591–7.

11 . Zou X, Li S, Fang M, Hu M, Bian Y, Ling J, et al.. "Acute Physiology and Chronic Health Evaluation II Score as a Predictor of Hospital Mortality in Patients of Coronavirus Disease 2019" . Crit Care Med. 2020Aug 1; 48(8):e657.

12 . Stephens JR, Stümpfle R, Patel P, Brett S, Broomhead R, Baharlo B, et al.. "Analysis of Critical Care Severity of Illness Scoring Systems in Patients With Coronavirus Disease 2019: A Retrospective Analysis of Three U.K. ICUs" . Crit Care Med. 2021; 49(1):e105.

13 . "Türkiye Cumhuriyeti Sağlık Bakanlığı Halk Sağlığı Genel Müdürlüğü" . COVID-19 Rehberi. 2020;2 Nisan.

14 . Alhazzani W, Møller MH, Arabi YM, Loeb M, Gong MN, Fan E, et al.. "Surviving Sepsis Campaign: guidelines on the management of critically ill adults with Coronavirus Disease 2019 (COVID-19)" . Intensive Care Med. 2020May; 46(5):854–887.

15 . Vandenbrande J, Verbrugge L, Bruckers L, Geebelen L, Geerts E, Callebaut I, et al.. "Validation of the Acute Physiology and Chronic Health Evaluation (APACHE) II and IV Score in COVID-19 Patients" . Crit Care Res Pract. 2021Jun19; 2021:5443083.

16 . Vicka V, Januskeviciute E, Miskinyte S, Ringaitiene D, Serpytis M, Klimasauskas A, et al.. "COVID-19 viral load not associated with disease severity: findings from a retrospective cohort study" . BMC Infect Dis. 2021Nov 22; 21(1):1173.

17 . "A Management Information publication for Scotland Scottish Intensive Care Society Audit Group report on COVID-19" .; Available from: https://www.statisticsauthority.gov.uk/wp-content/uploads/2016/06/National-Statisticians.

18 . , Cyprys ADEF P, Rutkowska BDEF K, Madowicz ABDEF J, Knapik Corresponding Author P, Knapik P. "Intensive Care Unit Admissions During the First 3 Months of the COVID-19 Pandemic in Poland: A Single-Center, Cross-Sectional Study" . Med Sci Monit. 2020Sep26; 26:e926974.

19 . ICNARC - Reports. Available from: https://www.icnarc.org/Our-Audit/Audits/Cmp/Reports.

20 . Australian and New Zealand Intensive Care Society (ANZICS). "ANZICS CORE COVID-19 Report - VIC 01 January to 30 September 2020" . 2020. https://www.anzics.com.au/annual-reports/.

21 . Primmaz S, Le Terrier C, Suh N, Ventura F, Boroli F, Bendjelid K, et al.. "Preparedness and Reorganization of Care for Coronavirus Disease 2019 Patients in a Swiss ICU: Characteristics and Outcomes of 129 Patients" . Crit care Explor. 2020Aug; 2(8):e0173.

22 . Armstrong RA, Kane AD, Kursumovic E, Oglesby FC, Cook TM. "Mortality in patients admitted to intensive care with COVID ?19: an updated systematic review and meta-analysis of observational studies" . Anaesthesia. 2021Apr 1; 76(4):537.

23 . Ge E, Li Y, Wu S, Candido E, Wei X. "Association of pre-existing comorbidities with mortality and disease severity among 167,500 individuals with COVID-19 in Canada: A population-based cohort study. Augusto O, editor" . PLoS One. 2021Oct 5; 16(10):e0258154.

24 . Bravata DM, Perkins AJ, Myers LJ, Arling G, Zhang Y, Zillich AJ, et al.. "Association of Intensive Care Unit Patient Load and Demand With Mortality Rates in US Department of Veterans Affairs Hospitals During the COVID-19 Pandemic" . JAMA Netw Open. 2021Jan 4; 4(1):e2034266–e2034266.

25 . Poudel A, Poudel Y, Adhikari A, Aryal BB, Dangol D, Bajracharya T, et al.. "D-dimer as a biomarker for assessment of COVID-19 prognosis: D-dimer levels on admission and its role in predicting disease outcome in hospitalized patients with COVID-19" . PLoS One. 2021Aug 1; 16(8August2021).

26 . Lino K, Guimarães GMC, Alves LS, Oliveira AC, Faustino R, Fernandes CS, et al.. "Serum ferritin at admission in hospitalized COVID-19 patients as a predictor of mortality" . Brazilian J Infect Dis. 2021Mar 1; 25(2).

27 . Hu R, Han C, Pei S, Yin M, Chen X. "Procalcitonin levels in COVID-19 patients" . Int J Antimicrob Agents. 2020Aug 1; 56(2):106051.