Evolution of COVID-19 mortality over time: results from the Swiss hospital surveillance system (CH-SUR)

Roelens, M. and Martin, A. and Friker, B. and Sousa, F. M. and Thiabaud, A. and Vidondo, B. and Buchter, V. and Gardiol, C. and Vonlanthen, J. and Balmelli, C. and Battegay, M. and Berger, C. and Buettcher, M. and Cusini, A. and Flury, D. and Heininger, U. and Niederer-Loher, A. and Riedel, T. and Schreiber, P. W. and Sommerstein, R. and Troillet, N. and Tschudin-Sutter, S. and Vetter, P. and Bernhard-Stirnemann, S. and Corti, N. and Gaudenz, R. and Marschall, J. and Nussbaumer-Ochsner, Y. and Senn, L. and Vuichard-Gysin, D. and Zimmermann, P. and Zucol, F. and Iten, A. and Keiser, O.. (2021) Evolution of COVID-19 mortality over time: results from the Swiss hospital surveillance system (CH-SUR). Swiss Med Wkly, 151. w30105.

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BACKGROUND: When the periods of time during and after the first wave of the ongoing SARS-CoV-2/COVID-19 pandemic in Europe are compared, the associated COVID-19 mortality seems to have decreased substantially. Various factors could explain this trend, including changes in demographic characteristics of infected persons and the improvement of case management. To date, no study has been performed to investigate the evolution of COVID-19 in-hospital mortality in Switzerland, while also accounting for risk factors. METHODS: We investigated the trends in COVID-19-related mortality (in-hospital and in-intermediate/intensive-care) over time in Switzerland, from February 2020 to June 2021, comparing in particular the first and the second wave. We used data from the COVID-19 Hospital-based Surveillance (CH-SUR) database. We performed survival analyses adjusting for well-known risk factors of COVID-19 mortality (age, sex and comorbidities) and accounting for competing risk. RESULTS: Our analysis included 16,984 patients recorded in CH-SUR, with 2201 reported deaths due to COVID-19 (13.0%). We found that overall in-hospital mortality was lower during the second wave of COVID-19 than in the first wave (hazard ratio [HR] 0.70, 95% confidence interval [CI] 0.63- 0.78; p <0.001), a decrease apparently not explained by changes in demographic characteristics of patients. In contrast, mortality in intermediate and intensive care significantly increased in the second wave compared with the first wave (HR 1.25, 95% CI 1.05-1.49; p = 0.029), with significant changes in the course of hospitalisation between the first and the second wave. CONCLUSION: We found that, in Switzerland, COVID-19 mortality decreased among hospitalised persons, whereas it increased among patients admitted to intermediate or intensive care, when comparing the second wave to the first wave. We put our findings in perspective with changes over time in case management, treatment strategy, hospital burden and non-pharmaceutical interventions. Further analyses of the potential effect of virus variants and of vaccination on mortality would be crucial to have a complete overview of COVID-19 mortality trends throughout the different phases of the pandemic.
Faculties and Departments:09 Associated Institutions > Swiss Tropical and Public Health Institute (Swiss TPH)
09 Associated Institutions > Swiss Tropical and Public Health Institute (Swiss TPH) > Department of Epidemiology and Public Health (EPH) > Biostatistics > Bayesian Modelling and Analysis (Vounatsou)
UniBasel Contributors:Martin, Alexis
Item Type:Article, refereed
Article Subtype:Research Article
ISSN:1424-3997 (Electronic)0036-7672 (Linking)
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:20 Dec 2022 14:56
Deposited On:20 Dec 2022 14:56

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