COVID-19 and critical care admissions in the UK: using routine data during a pandemic.

by:
Alice M Jackson

The Intensive Care National Audit and Research Centre (ICNARC) collates, reports and audits data for all National Health Service adult critical care admissions in the UK (England, Wales and Northern Ireland). Since the beginning of March 2020, 245 critical care units across the UK have submitted data on 6720 patients admitted with confirmed COVID-19, with data on outcomes in 4078 (61%) (1). In the report, patient demographics, markers of disease severity, length of stay, requirement for organ support and death or discharge from critical care are presented. Approximately a third of patients are from critical care units in London.

The mean age of patients was 59.4 (±12.5) years, 72% were men, half were in the two highest deprivation quintiles (where a higher number equates to more deprivation) and race was reported as Black, Asian or was unspecified (but non-White) in 34% of patients. In the 2011 England and Wales census, 14% of the whole population and 40% of people living in London identified as non-White (2). The burden of comorbidity is not well-described in the report, which only provides data about ‘very severe comorbidities’; in the case of cardiovascular disease, this is defined as cardiovascular disease with symptoms at rest in the six months prior to admission to critical care, and was present in 0.4% of patients.

Amongst 4078 patients with data on outcomes, advanced cardiovascular support (defined as the use of pharmacological inotropic or chronotropic support, or continuous cardiac output monitoring, or insertion of an intra-aortic balloon pump, or temporary cardiac pacing) was required in 27%, for a median duration of 3 (IQR 1-5) days –  5% more than required the same support when admitted to critical care with viral pneumonia from 2017-2019. As expected, nearly all of these patients (98.6%) required some form other additional organ support. Of those who required advanced cardiovascular and advanced respiratory support (n=613, 15%), the case-fatality rate during the critical care admission was 73%, increasing to 87% when renal replacement therapy was also required (n=440, 11%).

In the UK, routinely collected data like these are a rich source of information and can provide a comprehensive description of the emerging epidemiology of a new disease early in its course, such as with COVID-19. In England and Wales, population-level mortality datasets are collated and reported by the Office for National Statistics, and in Scotland by National Records for Scotland. Linkage of mortality datasets with other routine datasets, such as hospital admissions, is also possible. In Scotland, this is done through a combination of deterministic matching, which involves matching a unique patient identifier assigned to each individual in Scotland at birth, and probabilistic matching, which involves the use of other variables (such as name, date of birth or postcode) to determine whether the records belong to the same individual (3). In recent weeks, this existing infrastructure has allowed the UK to produce regular reports on health outcomes relating to COVID-19 in a timely and cost-effective fashion. Going forward, routine data such as these will not only facilitate research on the direct health effects of COVID-19, but also on the wider consequences of the pandemic.

References
1) https://www.icnarc.org/Our-Audit/Audits/Cmp/Reports. ICNARC report on COVID-19 in critical care 24 April 2020. (Accessed 28 April 2020)

2) http://www.nomisweb.co.uk/census/2011/dc2101ew. Ethnic group by sex and age. (Accessed 28 April 2020)

3) Fleming M, Kirby B, Penny K. Record linkage in Scotland and its applications to health research. J Clin Nurs. 2012;21(19-20):2711-2721.

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