Characteristics and outcome of COVID-19 patients admitted to the ICU: a nationwide cohort study on the comparison between the first and the consecutive upsurges of the second wave of the COVID-19 pandemic in the Netherlands
Authors: Dongelmans Dave A. , Termorshuizen Fabian , Brinkman Sylvia , Bakhshi-Raiez Ferishta , Arbous M. Sesmu , de Lange Dylan W. , van Bussel Bas C. T. , de Keizer Nicolette F. ,   the Dutch COVID-19 Research Consortium, Verbiest Dirk P , te Velde Leo F , van Driel Erik M , Rijpstra Tom , Elbers Paul W. G. , Georgieva Lyuba , Verweij Eva , de Jong Remko M , van Iersel Freya M , Koning Dick T. J. J. , Rengers Els , Kusadasi Nuray , Erkamp Michiel L , van den Berg Roy , Jacobs Cretièn J. M. G. , Epker Jelle L , Rijkeboer Annemiek A , de Bruin Martha T , Spronk Peter , Draisma Annelies , Versluis Dirk Jan , van den Berg Lettie A. E. , Mos Marissa Vrolijk-de , Lens Judith A , Mehagnoul-Schipper D Jannet , Gommers Diederik , Lutisan Johan G , Hoeksema Martijn , Pruijsten Ralph V , Kieft Hans , Rozendaal Jan , Nooteboom Fleur , Boer Dirk P , Janssen Inge T. A. , van Gulik Laura , Koetsier M Peter , Silderhuis Vera M , Schnabel Ronny M , Drogt Ioana , de Ruijter Wouter , Bosman Rob J , Frenzel Tim , Urlings-Strop Louise C , Dijkhuizen Allard , Hené Ilanit Z , de Meijer Arthur R , Holtkamp Jessica W. M. , Postma Nynke , Bindels Alexander J. G. H. , Wesselink Ronald M. J. , van Slobbe-Bijlsma Eline R , van der Voort Peter H. J. , Eikemans Bob J. W. , Barnas Michel G. W. , Festen-Spanjer Barbara , van Lieshout Maarten , Gritters Niels C , van Tellingen Martijn , Brunnekreef Gert B , Vandeputte Joyce , Dormans Tom P. J. , Hoogendoorn Marga E , de Graaff Mart , Moolenaar David , Reidinga Auke C , Spijkstra Jan Jaap , de Waal Ruud 
Published: January 2022

Abstract
Background
To assess trends in the quality of care for COVID-19 patients at the ICU over the course of time in the Netherlands.

Methods
Data from the National Intensive Care Evaluation (NICE)-registry of all COVID-19 patients admitted to an ICU in the Netherlands were used. Patient characteristics and indicators of quality of care during the first two upsurges (N = 4215: October 5, 2020–January 31, 2021) and the final upsurge of the second wave, called the ‘third wave’ (N = 4602: February 1, 2021–June 30, 2021) were compared with those during the first wave (N = 2733, February–May 24, 2020).

Results
During the second and third wave, there were less patients treated with mechanical ventilation (58.1 and 58.2%) and vasoactive drugs (48.0 and 44.7%) compared to the first wave (79.1% and 67.2%, respectively). The occupancy rates as fraction of occupancy in 2019 (1.68 and 1.55 vs. 1.83), the numbers of ICU relocations (23.8 and 27.6 vs. 32.3%) and the mean length of stay at the ICU (HRs of ICU discharge = 1.26 and 1.42) were lower during the second and third wave. No difference in adjusted hospital mortality between the second wave and the first wave was found, whereas the mortality during the third wave was considerably lower (OR = 0.80, 95% CI [0.71–0.90]).

Conclusions
These data show favorable shifts in the treatment of COVID-19 patients at the ICU over time. The adjusted mortality decreased in the third wave. The high ICU occupancy rate early in the pandemic does probably not explain the high mortality associated with COVID-19.