Abstract
BackgroundIncreasing age is the strongest known risk factor for severe COVID-19 disease but information on other factors is more limited.MethodsAll cases of COVID-19 diagnosed from January–October 2020 in New South Wales Australia were followed for COVID-19-related hospitalisations, intensive care unit (ICU) admissions and deaths through record linkage. Adjusted hazard ratios (aHR) for severe COVID-19 disease, measured by hospitalisation or death, or very severe COVID-19, measured by ICU admission or death according to age, sex, socioeconomic status and co-morbidities were estimated.ResultsOf 4054 confirmed cases, 468 (11.5%) were classified as having severe COVID-19 and 190 (4.7%) as having very severe disease. After adjusting for sex, socioeconomic status and comorbidities, increasing age led to the greatest risk of very severe disease. Compared to those 30–39 years, the aHR for ICU or death from COVID-19 was 4.45 in those 70–79 years; 8.43 in those 80–89 years; 16.19 in those 90+ years. After age, relative risks for very severe disease associated with other factors were more moderate: males vs females aHR 1.40 (95%CI 1.04–1.88); immunosuppressive conditions vs none aHR 2.20 (1.35–3.57); diabetes vs none aHR 1.88 (1.33–2.67); chronic lung disease vs none aHR 1.68 (1.18–2.38); obesity vs not obese aHR 1.52 (1.05–2.21). More comorbidities was associated with significantly greater risk; comparing those with 3+ comorbidities to those with none, aHR 5.34 (3.15–9.04).ConclusionsIn a setting with high COVID-19 case ascertainment and almost complete case follow-up, we found the risk of very severe disease varies by age, sex and presence of comorbidities. This variation should be considered in targeting prevention strategies.
Highlights
Since SARS-CoV-2 emerged in late 2019 efforts have been underway to understand the epidemiology of both the infection and the disease it causes, COVID-19, in order to reduce its health impacts
From 1 January to 5 October 2020 there were 4055 confirmed cases of COVID-19 diagnosed in New South Wales (NSW); their mean age was 44.7 years (SD 20.2), 49.8% (n = 2019) were female, 84.2% (n = 3413) were resident in a major city and 34.7% (n = 1406) were classified in the lower 50% of socioeconomic deciles (7.2%, n = 290, were missing socioeconomic classification)
When we restricted analyses to cases who had an onset date from 1 March 2020, the majority of cases were included in analyses (4004/4054, 99%) so findings were unchanged. The strengths of this analysis compared to other reports is the inclusion of all cases of COVID-19 diagnosed in a setting that has had high testing, low positivity and robust contact tracing throughout the COVID-19 pandemic
Summary
Since SARS-CoV-2 emerged in late 2019 efforts have been underway to understand the epidemiology of both the infection and the disease it causes, COVID-19, in order to reduce its health impacts. Liu et al BMC Infectious Diseases (2021) 21:685 infection such as health and aged care workers, and those for whom the infection, if acquired, has a higher likelihood of causing severe disease or death. A study from a large electronic primary care database of 17 million people in the UK reported lower risks of death from COVID-19 among those with hypertension (aHR 0.89) [3]. Possible explanations for these differences across studies include the study sampling frame used, and the extent to which confounders were adjusted for [4]. Increasing age is the strongest known risk factor for severe COVID-19 disease but information on other factors is more limited
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