Published today in The Lancet Respiratory Medicine, the study examined routine patient data collected between January 2020 to 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.
The analysis reviewed several respiratory diseases and included data from 1.09 million people with asthma, 193,520 people with chronic obstructive pulmonary disease 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 compared with 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 chronic obstructive pulmonary disease (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 quite rightly 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.
‘Our analysis suggests that the risk of hospital admission from severe Covid-19 in a person with asthma is equivalent to the risk for people without asthma who are three to five years older. For people with COPD or interstitial lung disease, their risk would be equivalent to the risk for people without these conditions who are seven to eight years older.
‘As data has continued to emerge, it is right to challenge the assumptions that respiratory disease is a severe risk and revisit the guidance. Based on the analysis we’ve conducted, people with chronic asthma can be reassured that while they are unfortunately at a modestly increased risk of hospitalisation from Covid-19, their risk of death is no different to those without asthma.’
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.
The researchers were funded by the National Institute for Health Research Oxford Biomedical Research Centre and the Wellcome Trust, and the data for this study was obtained through the QResearch database of electronic healthcare records.
Association between pre-existing respiratory disease and its treatment, and severe COVID-19: a population cohort study
Paul Aveyard, Min Gao, Nicola Lindson et al. Lancet Respir Med 2021