As emergency rooms worldwide are flooded with a wave of new COVID-19 patients, a large study in the United Kingdom has laid out the deadly consequences of delayed critical care.

Nearly 27 million individuals attended a major emergency room in England from 2016 to 2018, waiting on average just under five hours for a course of action. This is despite a four-hour operational standard adopted by the National Health Service (NHS) back in 2004.

Tragically, nearly 434,000 of those attendees would pass away within a month, a statistic that became more likely after five hours of waiting.

If a patient had to wait between six to eight hours, they were, on average, 8 percent more likely to die of any cause in the next 30 days. That's one extra death for every 82 patients who weren't treated within six hours.

If a patient had to wait more than eight hours, their likelihood of dying over the following month increased to 10 percent.

"Let nobody be in doubt any longer, the [NHS] four-hour operational target is, as many of us have always known, of key importance to patient safety," writes physician Derek Prentice from the Royal College of Emergency Medicine in a linked editorial.

"Patients are, and will continue to be, grateful for it and for the publication of this paper."

The same operational targets are also in place in other nations, like Australia and the United States, but that doesn't mean ERs consistently enforce the standards.

Even before the pandemic, it took the average patient in the UK just under five hours to get a bed in the emergency room. Between 2016 and 2018, nearly 40 percent of patients were waiting beyond the four-hour standard.

The findings are purely observational, which means they can't tell us why longer wait times are linked to higher death rates.

That said, researchers write that "there are a number of clinically plausible reasons to accept that" delaying critical care can lead to severe and sometimes fatal outcomes.

When there are not enough beds in the emergency room, for instance, patients may have delayed access to life-saving treatments, like pain medicine, antibiotics, or surgery. Plus, once these patients are finally admitted, it's usually at night, when staffing levels are lowest.

Significant wait times in the ER are also linked to an increase in the length of time patients spend in the hospital, which leaves them susceptible to infection and delirium, especially among older individuals.

In a global pandemic, those risks are even greater. Before the Omicron variant began to spread more widely, hospital beds in the UK were already nearing capacity, with a record 6 million people on hospital waiting lists.

With the arrival of a new SARS-CoV-2 variant, patients with serious ailments sometimes wait five days to get admitted to the ER.

It's a disaster doctors in the UK have seen coming for more than a decade.

In 2018, Prentice warned that the NHS had fewer acute beds relative to the population than almost any other similar health system in the world.

"For at least the last 12 years and more, we have seen cuts after cuts to the budget of the NHS, leading to reduced bed numbers and staffing," writes Prentice in the new editorial.

"This is bad enough in itself but has been further compounded by repeated large reductions in central government financial support to local authorities, with a devastating impact on social care. The result has been fewer beds in hospitals and a grave lack of social care provision for those patients ready for discharge […] Thanks to this report, we now have confirmation that such delay kills patients."

The study was published in Emergency Medicine Journal.