An analysis of 8.3 million health care records in England shows that people with asthma have only a small increased risk of developing severe Covid-19.
The study, led by University of Oxford researchers, examined routine patient data collected between January and April 2020 to generate risk assessments for severe COVID-19 in people with chronic respiratory diseases. Unlike previous studies of people hospitalised with COVID-19, which suggest large increases in risk associated with underlying respiratory disease, this analysis demonstrates that the risk of severe COVID-19 is only modestly raised over the risk in people without such conditions.
Published in The Lancet Respiratory Medicine, the study, which was supported by the NIHR Oxford Biomedical Research Centre (BRC), reviewed several respiratory diseases and included data from 1.09 million people with asthma, 193,520 people with chronic obstructive pulmonary disease (COPD) and 5,677 people with other interstitial lung disease. It compared the risks in these groups to 7 million people without respiratory diseases.
When adjusted for age, sex, demographic factors, underlying health conditions and in comparison to those without respiratory diseases, people with active asthma and severe asthma were at 26% and 29% higher relative risk of hospital admission with COVID-19, respectively, and around 30% higher relative risk of admission to intensive care.
There was no evidence that asthma was associated with an increased absolute risk of death from COVID-19, and the risks appeared similar for all ethnicities.
Having COPD was associated with a 50% increased risk of hospitalisation and 54% increased risk of death from COVID-19, which was higher in those with white ethnicity.
In patients with interstitial disease, a group of less common lung diseases which cause scarring of the lung tissue, the analysis shows a 30–50% increased relative risk of developing severe COVID-19 requiring hospital admission or leading to death. Patients in this group are currently advised to shield.
Though a concern for many, the risk of long-COVID in people with respiratory disease was not determined in this study.
Lead researcher Professor Paul Aveyard, a general practitioner and Professor of Behavioural Medicine in the University of Oxford’s Nuffield Department of Primary Care Health Sciences said: “At the start of the pandemic, the assumption that pre-existing respiratory disease would lead to an increased risk of serious COVID-19 illness was reasonable.
“COVID-19 has caused much anxiety in people with respiratory disease and while our results do show this group are at higher risk from developing severe COVID-19, when you put this into context with other known risk factors for hospitalisation, the relative risk for those with chronic respiratory disease are lower than the risks from being male or having diabetes, and are a small fraction of the everyday risk of death from any cause.
“As data has continued to emerge, it is right to challenge the assumptions that respiratory disease is a severe risk and revisit guidance. Based on the analysis we’ve conducted, people with chronic asthma can be reassured that while they are at a modestly increased risk of hospitalisation from COVID-19, their risk of death is no different to those without asthma,” said Professor Aveyard, the Oxford BRC’s Co-theme Lead for Obesity, Diet and Lifestyle.
The study also provides further evidence that the use of inhaled corticosteroids in those with airways diseases is not associated with substantial increased risk of severe COVID-19, but neither does it appear to be linked to reduced risk.
In their paper, the researchers state that it is possible that people with chronic respiratory diseases may have behaved differently during the early stages of the pandemic to avoid social contact, because they expected to be at a higher risk of severe disease, or because they were shielding, and so the true risk of severe COVID-19 for people with respiratory disease in this study may be underestimated.
Data for the analysis was obtained through the QResearch database of electronic healthcare records. As well as the Oxford BRC, the study was funded by the Wellcome Trust.