Table 1.

Database search strategy of MEDLINE and EMBASE for the period January 2019 to 5 January 2021

COVID-19 (TI, AB, KW)	Risk stratification (TI, AB, KW)	Mortality (TI, AB, KW)
COVID-19	Prognos*4 adj2 model/score/algorithm /tool	Hospital Mortality (MeSH)
COVID-2019	Clinical decision tool	Death*1
SARS-CoV-2	Predicti* adj2 model/score/algorithm /tool	Mortality
Severe acute respiratory syndrome coronarvirus 2	Risk adj2 model /predicti*/score/tool/ stratification	Fatal*5
2019-nCoV	Scor*3 system*1
	Mortality adj1 scor*3

The following search concepts were combined using Boolean operators: COVID-19 (TI, AB, KW) AND Risk stratification (TI, AB, KW) AND Mortality (TI, AB, KW)

AB, abstract; KW, keywords; TI, title, the '/' indicated a different variation.