The epidemiology of risk factors and short- and long-term outcome in the Swedish intensive care cohort

Abstract: The sepsis syndrome is present in ¼ to ⅓ of patients in intensive care units (ICUs) worldwide. The short-term prognosis is grim, with a 30-day mortality of 30–35%; however, the long- term outcomes are now being explored, as multi-professional follow-up after ICU care is increasingly being implemented. In 2020 the first and second waves of another severe infection, the Coronavirus disease 2019 (Covid-19) hit Sweden. The number of ICU beds were scaled up by several hundred percent while we simultaneously tried to understand the disease. Reports on risk factors for adverse outcomes in Covid-19 started to appear, but we needed to know more. Thus, we initiated this project aiming at assessing sepsis as an independent risk factor for later morbidity and mortality. Subsequently, with the onset of the pandemic, our focus shifted to identifying risk factors for adverse outcomes in Covid-19 and describing the functional recovery after severe Covid-19. We used the Swedish Intensive Care Registry and several governmental registries to this end.In Cox regression, we compared one-year ICU sepsis survivors without previous dementia with ICU patients without sepsis, finding no increased risk of dementia during follow- up. In a similar cohort, we assessed the impact of sepsis on long-term mortality and causes of death in a series of Cox and multinomial models. We found a surprisingly small overall association between sepsis and mortality and a persistently increased risk of infectious causes of death in sepsis patients. We compared the prevalence of several common comorbidities and medications as risk factors for ICU admission and mortality in ICU patients with Covid-19 with that of age- and sex-matched population controls and in patients discharged alive with those that were deceased at discharge. We found associations between several comorbidities and medications with these adverse outcomes. To better understand the meaning of these comorbidities as risk factors for short-term mortality, we compared them in logistic regression models on patients with Covid-19, sepsis and acute respiratory distress syndrome (ARDS). We found very similar impacts from the comorbidities; however, greater age was more associated with mortality in Covid-19 than in either sepsis or ARDS. Finally, we investigated the long-term functional recovery in ICU patients with Covid-19 compared to hospital-admitted patients with Covid-19 and population controls matched to the ICU group. The ICU patients had a markedly impeded recovery that was not explained by demographics or comorbidities in statistical models.