High risk groups for severe COVID-19 in a whole of population cohort in Australia

BMC Infect Dis. 2021 Jul 16;21(1):685. doi: 10.1186/s12879-021-06378-z.

Abstract

Background: Increasing age is the strongest known risk factor for severe COVID-19 disease but information on other factors is more limited.

Methods: All 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.

Results: Of 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).

Conclusions: In 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.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Aging*
  • COVID-19 / diagnosis*
  • COVID-19 / epidemiology*
  • COVID-19 / mortality
  • COVID-19 / virology
  • Cohort Studies
  • Comorbidity
  • Female
  • Hospitalization / statistics & numerical data*
  • Humans
  • Intensive Care Units*
  • Male
  • Middle Aged
  • New South Wales / epidemiology
  • Proportional Hazards Models
  • Risk Factors
  • SARS-CoV-2 / pathogenicity
  • Sex Characteristics*
  • Survival Analysis