Myrstad M, Rønningen PS, Tveita A, Rønning EJ, Ernø PE, Andersen EL, Walle-Hansen MM, Robertson AC, Thallinger M, Svendsen J, Haakonsen S, Tveit A, and Ihle-Hansen H
Background: The objective of this article is to summarise the course of illness and treatment for patients with COVID-19 admitted to Bærum Hospital since the start of the pandemic., Material and Method: We present data from a prospective observational study with the aim of systematising knowledge about patients admitted because of COVID-19. All patients admitted to Bærum Hospital up to and including 28 June 2021 were included. The results are presented for three waves of admissions: 9 March-23 June 2020, 21 September 2020-28 February 2021 and 1 March-28 June 2021., Results: A total of 300 patients, divided into 77, 101 and 122 in the three waves respectively, were admitted because of COVID-19. The number of hospital deaths during the three waves was 14 (18 %), 11 (11 %) and 5 (4 %) respectively. The average age of the patients was 67.6 years in the first wave and 53.3 years in the third wave. Altogether 204 patients (68 %) received medical oxygen or ventilation support, and 31 of these (10 % of all the patients) received invasive ventilation support. Non-invasive ventilation support was used as the highest level of treatment in 4 (8 %), 9 (13 %) and 17 (20 %) patients with respiratory failure in the three waves respectively. In the second and third wave, 125 out of 152 patients with respiratory failure (82 %) were treated with dexamethasone., Interpretation: Differences in patient characteristics and changes to treatment methods, such as the use of dexamethasone and non-invasive ventilation support, may have contributed to the apparent fall in mortality from the first to the third wave. Conditions that are not registered in the study, such as vaccination status, may also have impacted on mortality.