This version is outdated. The new version can be found here: COVID-19 and risk factors for severe disease – a rapid review, 2nd update
This rapid review is an update of a version published March 26th, 2020.
The findings in this memo are based on rapid searches in electronic databases, as well as manual searches on websites of health authorities in selected countries. Two researchers shared tasks related to study selection and synthesis of results. In the current situation, there is an urgent need for identifying the most important evidence quickly. Hence, we opted for this rapid approach despite an inherent risk of overlooking key evidence or making misguided judgements.
Association between single risk factors and severity of disease (univariate analyses)
A consistent finding from analyses of single risk factors is that age is strongly associated with severity COVID-19. Other risk factors also seem to be associated with severe outcomes for COVID-19 patients, but these findings are difficult to interpret since most of these risk factors are also strongly associated with age. We therefore emphasize findings from multivariate analyses that take several risk factors, including age, into account simultaneously.
Multivariate analyses of age and comorbidities as predictors of disease severity
We conclude that age stands out as the predominant single risk factor for severe disease.
The data indicates that comorbidities and other conditions may contribute additional risk, but this finding is less convincing than for age. Based on the findings from the largest study, patients with heart failure or a BMI>30 may be at particular risk, but this finding needs confirmation in future studies.
Based on the data at hand, the elderly are clearly the main group at risk of severe illness, among COVID-19 patients.