Mortality in patients admitted to intensive care with COVID-19: an updated systematic review and meta-analysis of observational studies

Abstract

The COVID-19 pandemic continues to cause critical illness and deaths internationally. Up to 31 May 2020, mortality in patients admitted to intensive care units (ICU) with COVID-19 was 41.6%. Since then, changes in therapeutics and management may have improved outcomes. Also, data from countries affected later in the pandemic are now available. We searched MEDLINE, Embase, PubMed and Cochrane databases up to 30 September 2020 for studies reporting ICU mortality among adult patients with COVID-19 and present an updated systematic review and meta-analysis. The primary outcome measure was death in intensive care as a proportion of completed ICU admissions, either through discharge from intensive care or death. We identified 52 observational studies including 43,128 patients, and first reports from the Middle East, South Asia and Australasia, as well as four national or regional registries. Reported mortality was lower in registries compared with other reports. In two regions, mortality differed significantly from all others, being higher in the Middle East and lower in a single registry study from Australasia. Although ICU mortality (95%CI) was lower than reported in June (35.5% (31.3-39.9%) vs. 41.6% (34.0-49.7%)), the absence of patient-level data prevents a definitive evaluation. A lack of standardisation of reporting prevents comparison of cohorts in terms of underlying risk, severity of illness or outcomes. We found that the decrease in ICU mortality from COVID-19 has reduced or plateaued since May 2020 and note the possibility of some geographical variation. More standardisation in reporting would improve the ability to compare outcomes from different reports.

Keywords: COVID-19; intensive care; meta-analysis; mortality; pandemic.

Figure 1

Flowchart of study inclusion.

Figure 2

Indicative summary of study recruitment, follow‐up and reporting. Data represent study admission dates (filled bar), length of final patient follow‐up (solid line) and publication date (diamond) for all studies, grouped by continent (represented by colour). ICNARC, Intensive Care National Audit and Research Centre; SICSAG, Scottish Intensive Care Society Audit Group; ANZICS, Australia and New Zealand Intensive Care Society. [Correction added on 9 February 2021, after first online publication: Fig. 2 was updated to reflect correct analysis of data].

Figure 3

Meta‐analysis of mortality of patients admitted to ICU with COVID‐19 infection. Data represent deaths per 100 completed intensive care admissions, grouped by geography and combined. Each study is represented by a square with outcome estimate in the centre and 95%CI as a horizontal line either side. The size of the square reflects the study weight based on random effects. The diamonds represent meta‐analysis results with outcome estimate in the centre and left and right sides corresponding to lower and upper confidence limits. ICNARC, Intensive Care National Audit and Research Centre; SICSAG, Scottish Intensive Care Society Audit Group; ANZICS, Australia and New Zealand Intensive Care Society. [Correction added on 9 February 2021, after first online publication: Fig. 3 was updated to reflect correct analysis of data].

Figure 4

Funnel plot of the number of patients with ICU outcomes against reported ICU mortality rate (%) for 52 included studies. The solid line represents the average reported mortality. The dotted lines represent three standard deviations. [Correction added on 9 February 2021, after first online publication: The solid line representation has now been explained]