TABLE 1.

Key items for framing aim, search strategy, and study inclusion and exclusion criteria for systematic review, following PICOTS (Population, Index prognostic factor, Comparator prognostic factor, Outcome, Timing, Setting) system

	Definition
Population	Patients diagnosed with COVID-19
Index prognostic factors	Any variable that was measured before hospital admission or diagnosis of COVID-19 and was examined for an association with any adverse event
Comparator prognostic factors	Not applicable
Outcomes	Any clearly defined adverse event in patients with COVID-19
Timing	Prognostic factors measured before diagnosis of COVID-19 or hospital admission, and predicting adverse outcomes at any time horizon
Setting	Patients visiting ambulatory healthcare facilities, patients admitted to hospital, or patients visiting emergency department

COVID-19: coronavirus disease 2019.