COVID-19 patients in England's busiest intensive care units (ICUs) in 2020 were 20% more likely to die, University College London research has found.
The increased risk was equivalent to gaining a decade in age.
By the end of 2020, one in three hospital trusts in England was running at higher than 85% capacity. Eleven trusts were completely full on 30 December, and the total number of people in intensive care with Covid has continued to rise since then.
The link between full ICUs and higher death rates was already known, but this study is the first to measure its effect during the pandemic.
Tighter lockdown restrictions are needed to prevent hospitals from being overwhelmed, says study author Dr Bilal Mateen.
Researchers looked at more than 4,000 patients who were admitted to intensive care units in 114 hospital trusts in England between April and June last year. They found the risk of dying was almost a fifth higher in ICUs where more than 85% of beds were occupied, than in those running at between 45% and 85% capacity. That meant a 60-year-old being treated in one of these units had the same risk of dying as a 70-year-old on a quieter ward.
The Royal College of Emergency Medicine sets 85% as the maximum safe level of bed occupancy. However, the team found there was no tipping point after which deaths rose - instead, survival rates fell consistently as bed-occupancy increased.
This suggests "a lot of harm is occurring before you get to 85%".
Source: BBC News, 14 January 2021