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  • July 2020
  • 5 minutes

What can insurers learn about COVID-19 risk factors from OpenSAFELY, the largest cohort study to date?

  • Anna Currie
  • John Ng
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In Brief
What factors are associated with risk of death from COVID-19? What does this mean for insurers? RGA's Anna Currie and John Ng provide an analysis of the recent OpenSAFELY study, the largest conducted to date by any country on COVID-19. 

The OpenSAFELY study, published in the prestigious journal Nature on July 8, is the largest conducted to date by any country on COVID-19, analyzing U.K. National Health Service (NHS) data from 17.3 million adults between February 1, 2020 and May 6, 2020. The OpenSAFELY analytics platform, covering 40% of all patients in England, linked COVID-19-related death data with longitudinal data held in primary care records processed electronically. A total of 10,926 COVID-19-attributable deaths were recorded.

In addition to the well-established COVID-19 mortality risk factors of age and gender, the study offers insights to insurers across a range of other risk factors: body mass index, smoking status, asthma, chronic respiratory disease, chronic heart disease, diabetes mellitus, chronic liver disease, chronic neurological diseases, common autoimmune diseases (rheumatoid arthritis, systemic lupus erythematosus, or psoriasis), organ transplant, asplenia, other immunosuppressive conditions (such as HIV), cancer, evidence of reduced kidney function, and raised blood pressure or a diagnosis of hypertension.

Study outcomes

The study confirmed a strong association of age and gender with COVID-19 mortality risk – 93% of the deaths in the study occurred in people aged over 60 years, and 56% of deaths in men. The ≥80 years age group had more than 20-fold increased risk compared with those aged 50-59 years, while male gender was associated with a more than 1.5-fold increased risk. Additional insights on age and gender differences are available in this paper.

The study also offers population-level support for racial and socioeconomic disparities in COVID-19 mortality and morbidity risks. All non-white ethnic groups had higher risk than those with white ethnicity. Those of Black ethnicity had a hazard ratio (HR) of 1.48, compared with those of Asian or Asian British of 1.44 and mixed ethnicity of 1.43. The previously held speculation that this may be due to a higher prevalence of comorbidity and deprivation among Black, Asian, and minority ethnic (BAME) communities can only partly explain the excess risk; further work is needed to fully understand this association.

Additionally, people from deprived social backgrounds were found to be at a higher risk of death, which could also not be explained by other risk factors, with the most deprived quintile having a HR of 1.80 compared to the least deprived, consistent with recent national statistics. This suggests that other social factors can increase the risk of COVID-19 infection or death from infection, and this also requires further research and understanding.

Data revealed important nuances in the risks of certain lifestyle decisions and underlying conditions:

  • The study supports a growing consensus that obesity increases risk, but the research also linked mortality rates to degree of obesity. The study divided body mass index (BMI) into obesity class I (30-34.9 kg/m2), class II (35-39.9 kg/m2), and class III (≥40 kg/m2) with fully adjusted HRs of 1.05, 1.40, and 1.92, respectively, showing an increasing risk of death with degree of obesity.
  • Both current and former smoking were associated with higher risk (HR of 1.43 and 1.14, respectively), but when the model was fully adjusted (not just for age and sex), evidence showed a slightly lower risk in current smokers (HR of 0.89). The salient fact here is that the risk to health associated with smoking far outweighs any very modest reduction in risk of those current smokers when considering the impact of smoking on COVID-19.
  • In those patients with asthma having had recent use of oral corticosteroid (OCS, recently defined as <1 year), the fully adjusted HR was 1.13 compared to no recent OCS use of 0.99. Likewise, people with controlled diabetes had a fully adjusted HR of 1.31 (HbA1c <58 mmol/mol = controlled), compared to those with uncontrolled diabetes (HbA1c >58 mmol/mol) with an HR of 1.95.
  • Those with a history of haematological malignancy were at more than 2.5 times increased risk up to five years from diagnosis and 1.6 times the risk thereafter. For other cancers, HRs were smaller and risk increases were largely observed among those diagnosed in the last year.
  • While most of the comorbidities considered were associated with a higher risk of COVID-19 deaths, no strong association was established between hypertension and mortality outcome. The high prevalence of hypertension is likely due to correlation with older age.


Since the outbreak of the pandemic, evidence has steadily emerged that those from certain backgrounds and those suffering with certain conditions show a greater propensity for negative outcomes with COVID-19. Highlighted among those, and perhaps most significant for the assessment of risk when underwriting, are individuals with diabetes (types I and II), particularly when this disease is not well controlled; obesity, especially in those in the higher ranges of BMI; and respiratory disease, particularly COPD, emphysema, bronchiectasis, and so on, as well as those with asthma who have recently needed oral steroids.

While much about COVID-19 risk factors remains unclear, data gathered from more comprehensive studies such as OpenSAFELY will provide greater clarity moving forward. Underwriters must remain proactive in staying up-to-date on the latest research and be ready to adjust guidelines as more becomes known.

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Meet the Authors & Experts

Anna Currie
Underwriting Research and Development Manager, RGA UK
John Ng
John Ng
Director, Longevity Analytics, Global Financial Solutions