Patients admitted to very full hospital intensive care units have an increased risk of dying, researchers have warned.
Those admitted to intensive care when hospitals are particularly full have the equivalent risk of being 11 years older than they actually are, academics hypothesised.
It comes as the Prime Minister warned that there is a “very substantial” risk of intensive care units (ICUs) being overwhelmed.
Boris Johnson told MPs on the Commons Liaison Committee: “If you ask me when do we think that the ICU capacity is likely to be overtopped, I can’t give you a prediction for that.
“But all I can say is that the risk is very substantial and we have to keep the pressure off the NHS and the only way to do that is to follow the current lockdown.”
The new study, led by experts at UCL, examined survival rates compared with ICU occupancy during the first wave of the pandemic.
The research, which has been published as a pre-print on MedRxiv, looked at data on 4,032 hospital patients with presumed or confirmed Covid-19 admitted to ICUs in England between April 2 and June 1 last year.
The authors found that 38.4% of the participants died,
They found that the likelihood of death was 19% higher when ICUs were fuller – at least 85% occupancy.
And the risk of death was lower during periods of “low occupancy”.
Corresponding author Dr Bilal Mateen, from the UCL Institute of Health Informatics, said: “To put into context as to why these results are so important – at the end of 2020, 37 of 123 recorded NHS trusts were experiencing over 85% ICU bed occupancy; 11 of these were completely full and the situation has only got more extreme.
“Our results show the association between risk of death and bed occupancy is linear and as occupancy increases the worse patients’ outcomes become.
“In the worst case scenario (when mechanical ventilator ICU occupancy goes from zero to 100%) a patient’s risk of death nearly doubles, which suggests that every % counts and hospital strain must be reduced.”
First author PhD researcher Harrison Wilde, from the University of Warwick, added: “What is unique about this study is that we’ve been able to put a number on the increased risk to patients for the first time in the context of surge capacity.
“For example, if a 40 year-old person is admitted to a full hospital, they effectively have the increased health risk of a 51 year-old.”