A comprehensive study from Norway shows that the incidence of sepsis cases is higher than previously reported, with 250 people per 100,000 people developing sepsis in Norway each year. This study debunks claims of increased reporting, shows a sharp decline in sepsis-related in-hospital mortality, and highlights an increase in recurrent sepsis cases, particularly among older adults.

The main reason for the increase in cases is that patients are repeatedly infected with sepsis, rather than dying from the first infection. Sepsis, sometimes informally called blood poisoning, is a serious condition. About 3,000 people die from sepsis in Norwegian hospitals every year.

Contrary to its common name, sepsis is not a true poisoning. Sepsis occurs when the immune system overreacts to an infection from bacteria, viruses, fungi or parasites. This overreaction can cause the immune system to damage human organs, leading to organ failure.

A new study of 300,000 hospital admissions with sepsis has found that the disease is more common than previously thought. However, many more patients are surviving than before, and the increase in cases is largely due to more people getting sepsis repeatedly rather than dying from the first infection.

"Every year, 250 people out of 100,000 people in Norway develop sepsis for the first time. We can see this from the average age-adjusted incidence rate. The incidence rate remained stable throughout the study period but was higher than previous studies," said Lise Tuset Gustad, a researcher at the Norwegian University of Science and Technology (NTNU), Nord University and Levanger Hospital.

A research team from the Central Norwegian Sepsis Research Center at the Norwegian National Normal University studied data for the entire period from 2008 to 2021 (inclusive). An article on the work has now been published in BMJOpen.

The researchers conducted a national registry study, which means the data quality is very high. To the researchers' knowledge, this is the first nationwide study of sepsis over such a long period of time that included all hospital admissions, not just those requiring intensive care.

They found that from 2008 to 2021 (inclusive), 317,705 people were hospitalized with sepsis. No less than 222,832 of these patients were admitted to hospital with sepsis for the first time.

Tousset Gustad was Nina Vibeche Skei's main academic supervisor during her PhD studies. Skye is a Consultant Anesthetist at Levanger Hospital.

The study debunks the notion that the rise in sepsis cases is due to increased awareness of the disease and therefore increased reporting. "The proportion of first-time sepsis cases per 100,000 inhabitants remained stable from 2008 to and including 2021," said Skei, the paper's first author.

Death rate dropped sharply

The study also found that many more people survived than before. "During this period, the mortality rate among patients admitted to the hospital for the first time with sepsis fell by no less than 43 percent," Skei said. "Whether the patient was suffering from sepsis for the first time or had had it before, hospital mortality rates fell by a third overall. The decrease in mortality rates is likely due to increased awareness of the disease and updated treatment guidelines."

The number of people admitted to hospital for a first infection with sepsis fell during the first two years of the Covid-19 pandemic. Researchers believe this may be due to social distancing, which has led to fewer infections in the overall population.

"We also found that fewer people over the age of 70 were admitted to hospital with sepsis. This may be due to the huge pressure on hospitals to prioritize certain patient groups." TusetGustad said. "These priorities have resulted in many people over the age of 70 not being admitted to the hospital compared with an ordinary year. So sepsis mortality rates in hospitals have increased during the pandemic," especially in 2021.

Covid-19 has made more people aware that infections can lead to organ failure. Many people were horrified by images of patients breathing on ventilators in intensive care units, first in Wuhan, then in Italy and finally in Norway. Bacterial and viral infections can cause organ failure in some patients. This is because some patients' immune systems mount an exaggerated response to infection. The patient may later develop sepsis, an infection accompanied by organ failure.

"Covid-19 has brought sepsis to the forefront. Before the pandemic, very little was known about sepsis caused by viral infections. The emergence of the SARS-CoV-2 virus has increased awareness of sepsis caused by this virus, and sepsis in general," Skei said.

Mortality rates higher due to Covid-19

"During 2020 and 2021, 30,000 people were admitted to hospital with sepsis, including 2,845 with Covid-19 sepsis. That's about 10%," Skei said.

Nearly 90% of first-time sepsis patients develop sepsis for reasons other than Covid-19, including during the pandemic. "However, a greater proportion of patients who developed sepsis for the first time from Covid-19 died," Skei said.

More people are suffering from recurring sepsis

The data also shows that more people are suffering from recurring sepsis than before.

During this period, there was an increase in the number of hospital admissions for recurrent sepsis. "The main reason for this increase is that the number of patients over 60 years old with recurrent sepsis has doubled," Skei said.

The number of people over the age of 80 suffering from recurrent sepsis has increased more than fivefold in 2021 compared with 2008.

"The reason is likely that we are getting better at treating other conditions, such as cancer, and we are living longer. Patients with weakened immune systems and the elderly are more susceptible to initial infection and recurrent sepsis."

The findings thus contradict the previous beliefs of many professionals. They attributed the increase in sepsis cases to changes in coding regulations for sepsis diagnoses. But that's not the case.

The same sepsis diagnosis codes were used throughout the study period, so we know these demonstrate real changes. These results may be unique both globally and in Norway. Previous studies in Norway have been relatively old, with a recent study using data from 2011 and 2012 showing only survival trends among sepsis patients over two years. This study looked at sepsis trends over 14 years.

"Being able to differentiate between first-time sepsis and recurrent sepsis is unique globally and is thanks to Norway's excellent medical registry," Tousset-Gustad said.

"Our findings should have implications for clinicians and politicians, as well as health policy planners. The burden of sepsis is greater than previously thought by the research community. However, we especially need to pay attention to the large increase in the number of patients with recurrent sepsis and identify preventive measures for this patient group," Skei said.

"Health policy planners need to take these results into consideration. We need to work to prevent recurrence of sepsis," said TusetGustad.