Factors associated with COVID-19-related death using OpenSAFELY

Working on behalf of NHS England, this paper used the OpenSAFELY platform to quantify a range of clinical risk factors for COVID-19-related death in the largest cohort study conducted by any country to date.

Nature, 2020

Paper information

Williamson, E.J., Walker, A.J., Bhaskaran, K. et al. Factors associated with COVID-19-related death using OpenSAFELY. Nature 584, 430–436 (2020).


Coronavirus disease 2019 (COVID-19) has rapidly affected mortality worldwide. There is unprecedented urgency to understand who is most at risk of severe outcomes, and this requires new approaches for the timely analysis of large datasets. Working on behalf of NHS England, we created OpenSAFELY—a secure health analytics platform that covers 40% of all patients in England and holds patient data within the existing data centre of a major vendor of primary care electronic health records. Here we used OpenSAFELY to examine factors associated with COVID-19-related death. Primary care records of 17,278,392 adults were pseudonymously linked to 10,926 COVID-19-related deaths. COVID-19-related death was associated with: being male (hazard ratio (HR) 1.59 (95% confidence interval 1.53–1.65)); greater age and deprivation (both with a strong gradient); diabetes; severe asthma; and various other medical conditions. Compared with people of white ethnicity, Black and South Asian people were at higher risk, even after adjustment for other factors (HR 1.48 (1.29–1.69) and 1.45 (1.32–1.58), respectively). We have quantified a range of clinical factors associated with COVID-19-related death in one of the largest cohort studies on this topic so far. More patient records are rapidly being added to OpenSAFELY, we will update and extend our results regularly.

Post-publication supplement

In the above paper, working on behalf of NHS England, we estimated associations between a wide range of individual-level factors including demographics and comorbidities, and risk of COVID-19 death, but we did not explore interactions between variables. It is plausible that associations may depend on age, and evaluating this would inform more accurate risk prediction. The purpose of this supplement is therefore to present associations between individual-level factors and COVID-19 death,stratified by age group.

Download the supplement.