Severity and case fatality rates of COVID-19: a systematic review, meta-analysis and an exploratory meta-regression of risk factors

Abstract

Background: We aimed to estimate prevalence of severe or critical illness and case fatality of COVID-19 in a systematic review and meta-analysis and to examine clinical, biochemical and radiological risk factors in a meta-regression.

Methods: PRISMA guidelines were followed. PubMed, Scopus and Web of Science were searched using pre-specified keywords.  Peer-reviewed empirical studies examining rates of severe illness, critical illness and case fatality among COVID-19 patients were examined. Random-effects meta-analyses were performed and adjusted for publication bias. Meta-regression analyses examined the moderator effects of risk factors.

Results: The meta-analysis included 29 studies representing 2,090 individuals. Pooled prevalence rates of severe illness, critical illness and case fatality among COVID-19 patients were 15%, 5% and 0.8% respectively. There were significant heterogeneity and publication bias related with the studies. Meta-regression analyses revealed that increasing age and elevated LDH consistently predicted severe / critical disease and case fatality. Moreover, hypertension; fever and dyspnea at presentation; and elevated CRP predicted increased severity.

Conclusions: Emerged predictors of severity and case fatality should inform clinicians to define at-risk endophenotypes. Differences in un-adjusted vs. adjusted pooled estimates indicates limited utility of small-scale studies and underscores the importance of multi-national studies to establish the morbidity and mortality rates in pandemics.