University of Bristol: Latest review shows intensive care mortality from COVID-19 continued to fall in 2020, but improvement is slowing

A meta-analysis of global studies has shown that intensive care morality from COVID-19 has continued to fall since the start of the pandemic, but the improvement is slowing and may have plateaued. The study, published today [2 February] in Anaesthesia (a journal of the Association of Anaesthetists), is by Professor Tim Cook, Consultant in Anaesthesia and Intensive Care Medicine at the Royal United Hospitals Bath NHS Foundation Trust and Honorary Professor in Bristol Medical School: Translational Health Sciences (THS) at the University of Bristol, and colleagues.

A previous meta-analysis* by Professor Cook and colleagues, published in July, 2020, concluded that overall mortality of COVID-19 patients in intensive care units (ICUs) has fallen from almost 60 per cent at the end of March 2020 to 42 per cent at the end of May 2020 — a relative decrease of around one third. This new study shows that, in studies up to October, 2020, ICU mortality has fallen again to 36 per cent. Thus, while the situation is still improving, the pace of progress has slowed substantially.

In this study, the authors used data from 52 observational studies including 43,128 patients, and, in addition to studies from Europe, North America and China that had been included in the earlier review, this study included first reports from the Middle East, South Asia and Australia, as well as four new national or regional registries.

The authors explain that, in the last few months, several studies have clarified which treatments do and do not provide benefit in the ICU management of COVID-19. Steroids (particularly dexamethasone) were shown in early June to improve survival in patients who are oxygen-dependent or receiving mechanical respiratory support, while other drugs including hydroxychloroquine, azithromycin, lopinavir/ritonavir and remdesivir have been shown to have no clear mortality benefit. They also note that management of COVID-19 has also likely evolved over the year with changes in approaches to oxygen therapy, fluid therapy and management of blood clotting.

The data show that in most geographical regions the ICU mortality rate from COVID-19 is 30– 40 per cent. Two geographical regions fall outside these limits and are statistically significantly different from other geographical regions. A single registry report from Victoria State in Australia (home to the city of Melbourne) reports very low mortality of 11 per cent. Conversely in the Middle East, mortality from a study including four countries is high at 62 per cent. There are several potential explanations for this finding, including the fact that studies from the Middle East included patients early in the pandemic when mortality was higher and those included in Australia arose later in the pandemic when mortality was lower.

The authors comment that the analysis is limited by the fact that there is no global standardisation of what constitutes intensive care, entry criteria for patients, admitted patients’ underlying health characteristics and severity of critical illness or reporting on the nature or intensity of treatments. Thus direct comparisons between studies from different regions can be difficult.

The authors said: “Our analysis includes studies published only up to October 2020. Since then, several variant viruses have emerged and in some countries transformed the trajectory of the pandemic through December 2020 and into January 2021. This has increased the demand on ICU in those locations and will merit further analysis in due course. To counter this, vaccination is now available in many countries and we can hope that this will also, over several months, positively impact on the pandemic trajectory and demand on ICU care.”

Professor Tim Cook concluded: “After our first meta-analysis on this last year showed a large drop in ICU mortality from COVID-19 from March to May 2020, this updated analysis shows that any fall in mortality rate between June and October 2020 appears to have flattened or plateaued.”

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