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Original article

Vol. 151 No. 4748 (2021)

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

  • Maroussia Roelens
  • Alexis Martin
  • Brian Friker
  • Filipe Maximiano Sousa
  • Amaury Thiabaud
  • Beatriz Vidondo
  • Valentin Buchter
  • Céline Gardiol
  • Jasmin Vonlanthen
  • Carlo Balmelli
  • Manuel Battegay
  • Christoph Berger
  • Michael Buettcher
  • Alexia Cusini
  • Domenica Flury
  • Ulrich Heininger
  • Anita Niederer-Loher
  • Thomas Riedel
  • Peter W. Schreiber
  • Rami Sommerstein
  • Nicolas Troillet
  • Sarah Tschudin-Sutter
  • Pauline Vetter
  • Sara Bernhard-Stirnemann
  • Natascia Corti
  • Roman Gaudenz
  • Jonas Marschall
  • Yvonne Nussbaumer-Ochsner
  • Laurence Senn
  • Danielle Vuichard-Gysin
  • Petra Zimmermann
  • Franziska Zucol
  • Anne Iten
  • Olivia Keiser
DOI
https://doi.org/10.4414/SMW.2021.w30105
Cite this as:
Swiss Med Wkly. 2021;151:w30105
Published
24.11.2021

Abstract

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.

References

  1. Cookson C, Burn-Murdoch J. Why the second wave of COVID-19 appears to be less lethal. Financial Times. 2020; Available at: https://www.ft.com/content/b3801b63-fbdb-433b-9a46-2174 05b1109f.
  2. Griffin S. Covid-19: second wave death rate is doubling fortnightly but is lower and slower than in March. BMJ. 2020 Oct;371:m4092. https://doi.org/10.1136/bmj.m4092
  3. James N, Menzies M, Radchenko P. COVID-19 second wave mortality in Europe and the United States. Chaos. 2021 Mar;31(3):031105. https://doi.org/10.1063/5.0041569
  4. COVID-⁠19 Switzerland | Coronavirus | Dashboard. Available at: https://www.covid19.admin.ch/en/overview. Accessed 2021 April 30.
  5. FOPH Federal Office of Public Health. Coronavirus: Situation in Switzerland. Available at: https://www.bag.admin.ch/bag/en/home/krankheiten/ausbrueche-epidemien-pandemien/aktuelle-ausbrueche-epidemien/novel-cov/situation-schweiz-und-international.html. Accessed 2021 May 7.
  6. Williamson EJ, Walker AJ, Bhaskaran K, Bacon S, Bates C, Morton CE, et al. Factors associated with COVID-19-related death using OpenSAFELY. Nature. 2020 Aug;584(7821):430–6. https://doi.org/10.1038/s41586-020-2521-4
  7. Bravi F, Flacco ME, Carradori T, Volta CA, Cosenza G, De Togni A, et al. Predictors of severe or lethal COVID-19, including Angiotensin Converting Enzyme inhibitors and Angiotensin II Receptor Blockers, in a sample of infected Italian citizens. PLoS One. 2020 Jun;15(6):e0235248. https://doi.org/10.1371/journal.pone.0235248
  8. Hothorn T, Bopp M, Günthard H, Keiser O, Roelens M, Weibull CE, et al. Assessing relative COVID-19 mortality: a Swiss population-based study. BMJ Open. 2021 Mar;11(3):e042387. https://doi.org/10.1136/bmjopen-2020-042387
  9. Maximiano Sousa F, Roelens M, Fricker B, Thiabaud A, Iten A, Cusini A, et al.; Ch-Sur Study Group. Risk factors for severe outcomes for COVID-19 patients hospitalised in Switzerland during the first pandemic wave, February to August 2020: prospective observational cohort study. Swiss Med Wkly. 2021 Jul;151:w20547. https://doi.org/10.4414/smw.2021.20547
  10. Dennis JM, McGovern AP, Vollmer SJ, Mateen BA. Improving Survival of Critical Care Patients With Coronavirus Disease 2019 in England: A National Cohort Study, March to June 2020. Crit Care Med. 2021 Feb;49(2):209–14. https://doi.org/10.1097/CCM.0000000000004747
  11. Thiabaud A, Iten A, Balmelli C, Senn L, Troillet N, Widmer A, et al. Cohort profile: SARS-CoV-2/COVID-19 hospitalised patients in Switzerland. Swiss Med Wkly. 2021 Feb;151:w20475. [cited 2021 Mar 15] Available from: https://smw.ch/article/doi/smw.2021.20475 https://doi.org/10.4414/smw.2021.20475
  12. Hospital-based surveillance of COVID-19 in Switzerland. 2020. Available at: https://www.unige.ch/medecine/hospital-covid/. Accessed 2021 April 30.
  13. Putter H, Fiocco M, Geskus RB. Tutorial in biostatistics: competing risks and multi-state models. Stat Med. 2007 May;26(11):2389–430. https://doi.org/10.1002/sim.2712
  14. Putter H. Tutorial in biostatistics: Competing risks and multi-state models Analyses using the mstate package. :43.
  15. Fine JP, Gray RJ. A Proportional Hazards Model for the Subdistribution of a Competing Risk. J Am Stat Assoc. 1999;94(446):496–509. https://doi.org/10.1080/01621459.1999.10474144
  16. Shepherd BE, Rebeiro PF ; Caribbean, Central and South America network for HIV epidemiology. Assessing and interpreting the association between continuous covariates and outcomes in observational studies of HIV using splines. J Acquir Immune Defic Syndr. 2017 Mar;74(3):e60–3. https://doi.org/10.1097/QAI.0000000000001221
  17. van Buuren S, Groothuis-Oudshoorn K. mice: Multivariate Imputation by Chained Equations in R. J Stat Softw. 2011;45(3):1–67. https://doi.org/10.18637/jss.v045.i03
  18. Rochwerg B, Agarwal A, Siemieniuk RA, Agoritsas T, Lamontagne F, Askie L, et al. A living WHO guideline on drugs for covid-19. BMJ. 2020 Sep;370:m3379. https://doi.org/10.1136/bmj.m3379
  19. Horby P, Lim WS, Emberson JR, Mafham M, Bell JL, Linsell L, et al.; RECOVERY Collaborative Group. Dexamethasone in Hospitalized Patients with Covid-19. N Engl J Med. 2021 Feb;384(8):693–704. https://doi.org/10.1056/NEJMoa2021436
  20. SAMS – Swiss Academy of Medical Sciences. Intensive care medicine: triage under resource scarcity. Available at: https://www.samw.ch/en/Ethics/Topics-A-to-Z/Intensive-care-medicine.html. Accessed 2021 July 27.
  21. Synthèse des indicateurs de suivi de l’épidémie COVID-19 - data.gouv.fr. Available at: /fr/datasets/synthese-des-indicateurs-de-suivi-de-lepidemie-covid-19/. Accessed 2021 June 18.
  22. Gessler N, Gunawardene MA, Wohlmuth P, Arnold D, Behr J, Gloeckner C, et al. Clinical outcome, risk assessment, and seasonal variation in hospitalized COVID-19 patients-Results from the CORONA Germany study. PLoS One. 2021 Jun;16(6):e0252867. https://doi.org/10.1371/journal.pone.0252867
  23. World Health Organization (WHO). Global Health Observatory - Life expectancy at birth. Available at: https://www.who.int/data/gho/data/indicators/indicator-details/GHO/life-expectancy-at-birth-(years). Accessed 2021 July 30.
  24. EuroMOMO. The European monitoring of excess mortality for public health action (EuroMOMO) network. Available at: https://www.euromomo.eu/. Accessed 2021 June 17.
  25. Société Suisse de Médecine Intensive (SSMI). Nouvelles recommandations de la SSMI sur l’oxygénothérapie pourles patients COVID-19. Available at: https://www.sgi-ssmi.ch/fr/covi19.html?file=files/Dateiverwaltung/COVID_19/Guidelines/IMSGCVCM_Neue%20Empfehlungen_Sauerstoff_Covid-19_FR_201027_03.pdf. Accessed 2021 July 21.
  26. Société Suisse de Médecine Intensive (SSMI). Recommandations pour l’admission en unité de soins intermédiaires et de soins intensifs des patients présentant une infection à SARS-CoV-2 –Epidémie Covid-19. Available at: https://www.sgi-ssmi.ch/fr/covi19.html?file=files/Dateiverwaltung/COVID_19/Guidelines/ISGCVCM_Triageempfehlungen_200318_FR.pdf
  27. Colloque médical COVID-19 | HUG - Hôpitaux Universitaires de Genève. Available at: https://www.hug.ch/maladies-infectieuses/colloque-medical-covid-19. Accessed 2021 May 7.
  28. Recommandations pour les professionnels de la santé | HUG - Hôpitaux Universitaires de Genève. Available at: https://www.hug.ch/coronavirus/recommandations-pour-professionnels-sante. Accessed 2021 June 18.
  29. Calligaro GL, Lalla U, Audley G, Gina P, Miller MG, Mendelson M, et al. The utility of high-flow nasal oxygen for severe COVID-19 pneumonia in a resource-constrained setting: A multi-centre prospective observational study. EClinicalMedicine. 2020 Nov;28:100570. [cited 2021 Jun 17] Available from: https://www.thelancet.com/journals/eclinm/article/PIIS2589-5370(20)30314-X/abstract https://doi.org/10.1016/j.eclinm.2020.100570
  30. Søgaard KK, Baettig V, Osthoff M, Marsch S, Leuzinger K, Schweitzer M, et al. Community-acquired and hospital-acquired respiratory tract infection and bloodstream infection in patients hospitalized with COVID-19 pneumonia. J Intensive Care. 2021 Jan;9(1):10. https://doi.org/10.1186/s40560-021-00526-y
  31. Ritchie H, Ortiz-Ospina E, Beltekian D, et al. Coronavirus Pandemic (COVID-19). Our World in Data 2020; Available at: https://ourworldindata.org/coronavirus. Accessed 2021 July 29.
  32. COVID-19. Stringency Index. Available at: https://ourworldindata.org/grapher/covid-stringency-index. Accessed 2021 July 29.
  33. Hammer GP, du Prel JB, Blettner M. Avoiding bias in observational studies: part 8 in a series of articles on evaluation of scientific publications. Dtsch Arztebl Int. 2009 Oct;106(41):664–8.
  34. Tracking SARS-CoV-2 variants. Available at: https://www.who.int/activities/tracking-SARS-CoV-2-variants. Accessed 2021 June 24.
  35. Challen R, Brooks-Pollock E, Read JM, Dyson L, Tsaneva-Atanasova K, Danon L. Risk of mortality in patients infected with SARS-CoV-2 variant of concern 202012/1: matched cohort study. BMJ. 2021 Mar;372(579):n579. https://doi.org/10.1136/bmj.n579
  36. Patone M, Thomas K, Hatch R, et al. Analysis of severe outcomes associated with the SARS-CoV-2 Variant of Concern 202012/01 in England using ICNARC Case Mix Programme and QResearch databases. medRxiv 2021; 2021.03.11.21253364. https://doi.org/10.1101/2021.03.11.21253364
  37. Sheikh A, McMenamin J, Taylor B, Robertson C ; Public Health Scotland and the EAVE II Collaborators. SARS-CoV-2 Delta VOC in Scotland: demographics, risk of hospital admission, and vaccine effectiveness. Lancet. 2021 Jun;397(10293):2461–2. https://doi.org/10.1016/S0140-6736(21)01358-1

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