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COVID-19 continues to contribute to higher mortality rates among people admitted to intensive care units, even when COVID-19 is not the primary reason for their admission.
New research published in the Medical Journal of Australia has shown that the coronavirus disease 2019 (COVID-19) continues to impact mortality rates in intensive care units (ICUs), despite widespread vaccinations and improved treatments for COVID-19.
The research used data from the Australian and New Zealand Intensive Care Society (ANZICS) adult patient database to compare the in-hospital mortality and ICU length of stay for people admitted to Australian and New Zealand ICUs during 2022–23 with COVID-19 pneumonitis, incidental or exacerbating SARS-CoV-2 infections, or without SARS-CoV-2 infections.
COVID-19 cases surged in Australia in 2022 with the relaxation of pandemic restriction policies and the emergence of the highly transmissible Omicron strain.
However, due to novel therapeutic strategies, natural community immunity and a high level of vaccination in the population, the severity of critical illness in people with SARS-CoV-2 infections was reduced.
“Consequently, a rising number of people admitted to ICUs have concomitant SARS-CoV-2 infections rather than primary diagnoses of COVID-19; these infections might be considered incidental or as exacerbating, depending on whether they contributed to the person being admitted to the ICU,” the authors wrote.
“Our findings suggest that incidental, exacerbating, and primary SARS-CoV-2 infections all increase the risk of in-hospital death.”
The data
The primary outcome of the study was to assess in-hospital mortality, with a secondary measure to assess the length of ICU stay.
Included in the analysis were 207 684 admissions of adults to 195 Australian and New Zealand ICUs during 2022–23.
The results showed that 2674 people (1.3%) had incidental SARS-CoV-2 infections, 4923 (2.4%) had exacerbating infections, and 3620 (1.7%) had a primary COVID-19 diagnosis.
“We found that a substantial majority of people admitted to intensive care with SARS-CoV-2 infections were admitted to the ICU for reasons other than primary COVID-19,” the authors wrote.
“Given their generally short stay in hospital before ICU admission, most were probably infected prior to coming to the hospital.”
Risk-adjusted in-hospital mortality was higher for patients with a primary SARS-CoV-2 infection, and also higher for incidental and exacerbating infections, than for patients without SARS-CoV-2 infection.
The median length of ICU stay was also longer for patients with primary, incidental or exacerbating SARS-CoV-2 infections than for people without infection, although the researchers note some of this discharge delay may relate to infection control procedures and the time needed for isolation.
Higher mortality and longer ICU stays
Despite the reduction in severity for many SARS-CoV-2 infections, the research shows even incidental and exacerbating infections are associated with longer stays in the ICU and a higher risk of death.
“The influence of incidental and exacerbating infection on risk-adjusted in-hospital mortality may validate the attribution classification system for SARS-CoV-2 infections,” the authors wrote.
“It also indicates the significance of concomitant SARS-CoV-2 infections, even when incidental, and consequently the need for ongoing vigilance and appropriate infection control and treatment for optimising outcomes for these patients.”
“As we enter the post-COVID-19 pandemic era, clinicians should be aware that patients with SARS-CoV-2 infections at ICU admission have a higher risk of death, irrespective of whether it is the primary cause of admission or an incidental finding,” the authors concluded.
Read the research in the Medical Journal of Australia.
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