Parameters for the pandemic – why the hospitalization rate is problematic as the only indicator

A woman comes out of a hospital, in the foreground is a sign with the inscription

The frequency of hospitalization indicates how many Covid-19 patients per 100,000 inhabitants admitted to a clinic within a week (image alliance / dpa / Uwe Anspach)

The so-called frequency of hospitalization or hospitalization rate must replace the occurrence of new corona infections as the most important variable for corona protection measures – which has been discussed for a long time. Meanwhile, the Bundestag has passed a new law on infection control. It contains the measures still possible for the federal states after the end of the epidemic on 25 November. These are linked to certain values ​​of the admission rate. This was decided by the Prime Ministers at the Federal Conference on 18 November.

From a value of three Therefore, the 2G rule will apply nationwide in a federal state at events, restaurant visits and the like.
From a value of six The 2G Plus rule applies.
From a value of nine Even stricter measures such as contact restrictions can be imposed, but the state parliament must then decide.

that hospitalization frequency provides information on the strain on hospitals caused by the corona pandemic. It indicates how many Covid 19 patients per 100,000 inhabitants were admitted to a clinic within a week. The previous peak was more than 15 around Christmas 2020.

However, the frequency of hospitalizations is critically seen as a key figure because it tends to underestimate the reality there due to late reports from the hospitals.

What criticism is there of the admission rate parameter?

The criticism of the incidence of admissions primarily concerns the reporting procedure. Data from hospitals often come with a delay, which is why the hospitalization rate, according to experts, is only a reliable value about two weeks later and is given too low daily.

We lag behind reality afterwards
Comment on the admission rate

According to epidemiologist Hajo Zeeb from the Leibniz Institute, the delays are due to the fact that the reporting channels are only relatively recently established. Sometimes a Covid diagnosis is made only after a patient has been admitted. This is why there are always late reports, making the hospitalization rate a “somewhat harsh indicator” that “does not really show what is happening,” Zeeb said on Deutschlandfunk.

Criterion admission rate – Interview with Hajo Zeeb, Leibniz Institute

At present, it can be assumed that the value represents a situation from a few days ago or in some federal states from ten days to two weeks ago. “And it’s obviously not optimal for control in this situation where intensive beds are scarce.”

Treatment in the intensive care unit for corona patients.  (icon image)

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Intensive care physician Christian Karagiannidis emphasized on Deutschlandfunk that the stressful clinical everyday life leaves no time for the constant filling of documents for which there is a lack of attention and staffing. Because the data is reported to the health department via fax, and sometimes it is forgotten.

Clinic utilization and hospitalization rate: Interview with Christian Karagiannidis (DIVI)

Use of SORMAS during the COVID-19 pandemic;  Kay Watty from the Helmholtz Center for Infection Research at the SORMAS hotline

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What other parameters could be useful?

Epidemiologist Hajo Zeeb emphasized in Dlf that it was right and necessary to look at the hospitals. In order to actually counteract congestion there, there is a need for more accurate information about the occupancy of the intensive care beds. It is the eye of the needle in the current situation. The intensive bedding indicator is available even faster than the hospitalization rate because it is reported for the day and is just as important in comparison. “I would have seen him at least as important when deciding on further action,” Zeeb said. He advocated a combined indicator that also takes into account the intensive care units and the incidence of new infections.

This summer, as part of its Covid control strategy, RKI developed such a phased concept for future corona measures and updated it in September, which consists of a triad of the incidence of new infections, hospital occupancy and intensive care unit occupancy with Covid 19 patients. There are thresholds for each indicator from which the next of the three levels takes effect. Depending on the level and framework (gastronomy, public transport, sports, etc.), RKI then proposes measures such as 3G, limitation of the number of people, removal of the obligation to wear a mask or the like.

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Months ago, the German hospital company also called for the incidence to be listed as an indicative value and instead brought a mix of twelve indicators into play to assess the pandemic situation, including hospitalization rate, free intensive care capacity, death, vaccination rate and R-value. President Gerald Gass explained in the Deutschlandfunk interview how the parameters could be visualized in a traffic light scheme. He stressed that it was more important to interpret the values ​​in context than to calculate the one “lucky formula”.

occurrence relevant? Interview Gerald Gass, German Hospital Society

Gérard Krause, Head of the Epidemiology Department at the Helmholtz Center for Infectious Disease Research (HZI) in Braunschweig, brought the following indicators into play: deaths, new admissions to the intensive care unit, hospitalizations, the number of incapacitated due to Covid-19 and the incidence of positive laboratory tests. Based on this, he calculates a total value, divided into five groups of those affected: by age, district, vaccination status, occupation and membership of a risk group.

Why has the incidence value of new infections played the main role so far?

In the first phase of the corona pandemic, it quickly became clear: With a time delay, high numbers of infections will mean that hospitals and intensive care units will be pushed to the limits of their resilience – and that the number of deaths will increase. In order to respond, the incidence of new corona infections was the best early indicator. The value describes the number of new corona infected per 100,000 inhabitants in seven days.

Graphic: New infections within the last seven days per. 100,000 inhabitants by age group

The incidence value has also played a crucial role in the course of the pandemic for the health authorities’ contact tracing. World Medical President Frank Ulrich Montgomery said in October 2020 at the then critical 50s for the seven-day incidence: “This is the number where health authorities stop being able to understand any infection and start tracking down the pre-infected people and other infected people properly in order to. ”

Why is the incidence value of new infections now less meaningful?

One reason is the advanced vaccination campaign: The majority of people, and especially the particularly vulnerable age groups, have been vaccinated, which is why the likelihood of ending up in hospital with a corona infection or dying from it has decreased. The current number of new infections needs to be assessed differently than before before the vaccines were available.

“In fact, we can generally cope with higher numbers,” says epidemiologist Hajo Zeeb on Dlf. Nevertheless, there is still a clear link between new infections and hospitalization: “About 0.8 or 0.9 percent of all those infected need to be hospitalized and treated there,” Zeeb says. The incidence of new infections also has its weaknesses as an indicator, because here too the reporting is not optimal. But it is an earlier indicator from which one can read what will happen in the near future.

Intensive care physicians warned as early as August that, despite the rising vaccination rate, there was a risk of a new wave of infections in the autumn, which could put the intensive care unit under a heavy burden. In a study at the time, different scenarios for the fall were simulated. The intensive bedding is therefore still proportional to the incidence. Thanks to the vaccinations, comparable intensive bed cover would only be obtained with a higher incidence than last winter. But from an incidence of 200 per. 100,000 again, a significant burden can be expected on the intensive care units with more than 3,000 Covid 19 patients, provided that the vaccination rate does not increase significantly.

“We still need the deposits because they tell us extremely well how the virus is spreading in the population,” said Christian Karagiannidis on Dlf. He is chairman of the German Society for Internal Intensive Care and Emergency Medicine.

Turning away from occurrence: Interview with intensive care physician Christian Karagiannidis

On the one hand, it is important to look at the affected age groups. On the other hand, vaccinated people can also become infected. “In this regard, the deposits remain the absolute most important value because it integrates an incredible amount of data, and of course it clearly precedes the occupancy of the hospitals,” says Karagiannidis. He therefore also advocated a triad of incidence values, hospital and intensive care unit coverage as early as August.

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