Lim · American journal of respiratory and critical care medicine 2021 · systematic review and meta-analysis · n=69 studies (57,420 patients)

Case Fatality Rates for Patients with COVID-19 Requiring Invasive Mechanical Ventilation. A Meta-analysis.

Cited 388 times in the scientific literature.

Level 3 - non-randomized controlled study

Systematic review and meta-analysis of observational studies

PubMed 33119402 · doi:10.1164/rccm.202006-2405OC · record verified 2026-08-29

What was done

Two authors searched PubMed, Embase, medRxiv, bioRxiv, a COVID-19 living systematic review, and national registry databases to determine case fatality rates (CFRs) among adults with confirmed COVID-19 requiring invasive mechanical ventilation (IMV). The primary outcome was reported CFR. Definitive hospital CFR (restricted to patients with completed discharge outcomes) was also evaluated, alongside subgroup analyses by age, geographic location, and study quality assessed by the Newcastle-Ottawa Scale.

What was found

Sixty-nine studies comprising 57,420 adult patients were included. The pooled reported CFR was 45% (95% CI, 39–52%). Fifty-four of 69 studies indicated whether hospital outcomes were available, but definitive hospital outcomes were reported for only 13,120 of the 57,420 patients (22.8%). In age-stratified analyses, pooled CFR ranged from 47.9% (95% CI, 46.4–49.4%) in patients aged 40 years or younger to 84.4% (95% CI, 83.3–85.4%) in patients older than 80 years. CFR was also higher in early pandemic epicenters. Heterogeneity was high (I² > 90%), while Egger's test showed no evidence of publication bias.

Why it matters

This review establishes a baseline mortality estimate for ventilated COVID-19 patients across the early phase of the pandemic, demonstrating that nearly half died and mortality increased sharply with older age.

Limits

Between-study heterogeneity was very high (I² > 90%). Definitive hospital outcomes were missing for 77.2% of the overall patient sample at the time of reporting, leaving substantial potential for bias. Included studies were observational and largely from early pandemic surges where strained intensive care capacity may have worsened outcomes.

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