Mortality due to COVID-19 during the pandemic: A comparison of first, secondo and third SMAtteo COvid19 REgistry (SMACORE)

The Behaviour of IL-6 and Its Soluble Receptor Complex during Different Waves of the COVID-19 Pandemic

In late December 2019, SARS-CoV-2 was identified as the cause of a new pneumonia (COVID-19), leading to a global pandemic declared by the WHO on 11 March 2020, with significant human, economic, and social costs. Although most COVID-19 cases are asymptomatic or mild, 14% progress to severe disease, and 5% develop critical illness with complications such as interstitial pneumonia, acute respiratory distress syndrome (ARDS), and multiple organ dysfunction syndrome (MODS). SARS-CoV-2 primarily targets the respiratory system but can affect multiple organs due to the widespread presence of angiotensin-converting enzyme 2 (ACE2) receptors, which the virus uses to enter cells. This broad distribution of ACE2 receptors means that SARS-CoV-2 infection can lead to cardiovascular, gastrointestinal, renal, hepatic, central nervous system, and ocular damage. The virus triggers the innate and adaptive immune systems, resulting in a massive cytokine release, known as a "cytokine storm", which is linked to tissue damage and poor outcomes in severe lung disease. Interleukin-6 (IL-6) is particularly important in this cytokine release, with elevated levels serving as a marker of severe COVID-19. IL-6 is a multifunctional cytokine with both anti-inflammatory and pro-inflammatory properties, acting through two main pathways: classical signalling and trans-signalling. Classical signalling involves IL-6 binding to its membrane-bound receptor IL-6R and then to the gp130 protein, while trans-signalling occurs when IL-6 binds to the soluble form of IL-6R (sIL-6R) and then to membrane-bound gp130 on cells that do not express IL-6R. The soluble form of gp130 (sgp130) can inhibit IL-6 trans-signalling by binding to sIL-6R, thereby preventing it from interacting with membrane-bound gp130. Given the central role of IL-6 in COVID-19 inflammation and its association with severe disease, we aimed to analyse the behaviour of IL-6 and its soluble receptor complex during different waves of the pandemic. This analysis could help determine whether IL-6 levels can serve as prognostic markers of disease severity.

Evolution of in-hospital patient characteristics and predictors of death in the COVID-19 pandemic across four waves: are they moving targets with implications for patient care?

Objectives

The aim of this work was to study characteristics, outcomes and predictors of all-cause death in inpatients with SARS-CoV-2 infection across the pandemic waves in one large teaching hospital in Italy to optimize disease management.

Methods

All patients with SARS-CoV-2 infection admitted to our center from March 2020 to June 2022 were included in this retrospective observational cohort study. Both descriptive and regression tree analyses were applied to identify factors influencing all-cause mortality.

Results

527 patients were included in the study (65.3% with moderate and 34.7% with severe COVID-19). Significant evolutions of patient characteristics were found, and mortality increased in the last wave with respect to the third wave notwithstanding vaccination. Regression tree analysis showed that in-patients with severe COVID-19 had the greatest mortality across all waves, especially the older adults, while prognosis depended on the pandemic waves in patients with moderate COVID-19: during the first wave, dyspnea was the main predictor, while chronic kidney disease emerged as determinant factor afterwards.

Conclusion

Patients with severe COVID-19, especially the older adults during all waves, as well as those with moderate COVID-19 and concomitant chronic kidney disease during the most recent waves require more attention for monitoring and care. Therefore, our study drives attention towards the importance of co-morbidities and their clinical impact in patients with COVID-19 admitted to hospital, indicating that the healthcare system should adapt to the evolving features of the epidemic.

Long-Term Survival among Patients Hospitalized for COVID-19 during the First Three Epidemic Waves: An Observational Study in a Northern Italy Hospital

The mortality rate of hospitalized COVID-19 patients differed strongly between the first three pandemic waves. Nevertheless, their long-term survival has been poorly assessed. The aim of this study was to compare the clinical characteristics and mortality rates of 825 patients with coronavirus disease 2019 (COVID-19) infection who were hospitalized at the Alessandria hub hospital, in Northern Italy, during the first fifty days of the first three pandemic waves. Each subject was followed in terms of vital status for six months from the date of hospital admission or until deceased. Patients admitted during the three waves differed in age (p = 0.03), disease severity (p < 0.0001), Charlson comorbidity index (p = 0.0002), oxygen therapy (p = 0.002), and invasive mechanical ventilation (p < 0.0001). By the end of follow-up, 309 deaths (38.7%) were observed, of which 186 occurred during hub hospitalization (22.5%). Deaths were distributed differently among the waves (p < 0.0001), resulting in being higher amongst those subjects admitted during the first wave. The COVID-19 infection was reported as the main cause of death and patients with a higher mortality risk were those aged ≥65 years [adjusted HR = 3.40 (95% CI 2.20-5.24)], with a higher disease severity [adjusted HR = 1.87 (95%CI 1.43-2.45)], and those requiring oxygen therapy [adjusted HR = 2.30 (95%CI 1.61-3.30)]. In conclusion, COVID-19 patients admitted to our hub hospital during the second and the third waves had a lower risk of long-term mortality than those admitted during the first. Older age, more severe disease, and the need for oxygen therapy were among the strongest risk factors for poor prognosis.