2.4 Study Quality Assessment:
The quality of the included studies was assessed using nine quality
assessment criteria adapted from Littell et al. (24): (1) Was the
research problem clearly mentioned? (2) Were the inclusion and exclusion
criteria clearly mentioned? (3) Were the subjects in the study
representative of the pathological population? (4) Were the
principaloutcome of the study clearly mentioned? (5) Was a control group
included? (6) Were effect of corticosteroid therapy clearly mentioned
(7) Were diagnosis method of COVID-19 clearly defined (8) Was a sample
size justification via power analysis provided? (9) Were potential
confounders properly controlled in the analysis? Each of the nine
criteria was scored on a scale of zero to two, depending on whether the
criterion was unmentioned or unmet (0), partially met (1), or completely
met (2). The possible total score ranged from zero to 18. The study
quality score was used to quantify the strength of existing evidence but
was not used in the study selection.