Older age, being male, deprivation, living in a densely populated area, ethnicity, obesity, and chronic kidney disease are associated with a positive test for COVID-19, according to results from 3,802 people tested for SARS-CoV-2 in the UK. The observational study was conducted between 28 January and 4 April using routine electronic health records data from GP practices across England (UK), and results are published in The Lancet Infectious Diseases.
Study author Simon de Lusignan from the University of Oxford (Oxford, UK) and Director of the Royal College of GPs Surveillance Centre, UK, says: “While clear trends have emerged from hospital data for the people with severe symptoms, the risk of infection among the general population remains a grey area. It’s important to know which groups in the wider community are most at risk of infection so that we can better understand SARS-CoV-2 transmission and how to prevent new cases.”
The authors note that other socio-economic factors, which were not measured in this study, may also be linked with SARS-CoV-2 infection, such as employment in high-risk jobs, education, income, and differences in access to healthcare and testing among ethnic groups. Further research is needed to understand these associations.
de Lusignan and colleagues analysed data from 587 people with positive results and 3,215 with negative results, collated by GP practices in England who are part of the Royal College of General Practitioners Research and Surveillance Centre primary care network.
Among adults, those aged 40 to 64 years were at the greatest risk of testing positive for SARS-CoV-2 (18.5% tested positive, 243 out of 1,316 people), compared with children aged up to 17 years (4.6%, 23 of 499). Among 1,612 men, 18.4% (296) tested positive, compared with 13.3% (291/2,190) of women.
The only clinical conditions significantly associated with a positive test were chronic kidney disease and obesity. Of 207 people with chronic kidney disease, 32.9% (68) tested positive, compared with 14.4% (519/3,595) without kidney disease. While 20.9% of people who were obese tested positive (142/680), compared with 13.2% (171/1,296) people of normal weight.
Compared with people of white ethnicity, of whom 15.5% (388 of 2,497) tested positive, the proportion of people of black ethnicity testing positive were much higher, at 62.1% (36 of 58 people). This finding remained significant after adjusting for comorbidities such as high blood pressure and diabetes, the prevalence of which is increased in black ethnic groups. The authors say that these results should be interpreted with caution, as there were small numbers of people from England’s minority ethnic groups in the study.
There was a large difference between people living in the most and least deprived areas. Of 668 people in the most deprived areas, 29.5% (197) tested positive, compared with 7.7% (143 of 1,855) in the least deprived areas. People in urban areas were more at risk than those in rural areas. Of 1,816 people tested in urban areas, 26.2% (476) tested positive, while in rural areas 5.6% tested positive (111 of 1,986).
Co-author Gayatri Amirthalingam, from Public Health England, says: “With each day that passes our knowledge of COVID- 19 improves. This analysis of primary care outcomes of individuals testing positive for virus is an important contribution to our wider understanding of how COVID-19 is affecting people of different demographic groups. This study, which uses data from the Oxford RCGP Research and Surveillance Centre, will also inform Public Heath England’s ongoing review into factors impacting health outcomes from COVID-19 that is to be completed by the end of May, 2020. This review will also analyse hospitalisations and mortality, including excess mortality, to provide further insight on how COVID-19 may be having a disproportionate impact on different groups. It will also determine the impact of occupation (including healthcare workers) where data is available.”