Acute asthma admissions sharply declined during lockdowns as air quality improved, study reveals

9th February 2024

Reduced pollution levels and better air quality during the Covid-19 pandemic lockdowns strongly correlated with lower rates of acute asthma care provision, according to new research led by the University of Birmingham.

The retrospective time-series study, published in the BMJ Open, investigated the link between acute asthma hospital admissions and specific air pollutant levels in four Oxford postcodes during the national lockdowns of March to June and November to December 2020.

For adult residents, acute asthma admissions fell from 78 per 100,000 residents in 2015-19, to 46 per 100,000 residents in 2020 – a reduction of 41%.

This reduction in acute asthma care coincided with levels of air pollution falling significantly. Different pollutants dropped by 18-33% when compared to average values for the previous five-year period.

For example, nitrogen dioxide (NO₂) reduced by 26.7% from a 2015-19 average of 14.6 μg m-3 to 10.7 μg m-3 in 2020.

Fine particulate matter (PM_2.5) saw a reduction of 33.5% from 10.1 μg m-3 in 2015-19 to 6.7 μg m-3 in 2020, and PM₁₀ reduced by 18.6% from 13.2 μg m-3 in 2015-19 to 10.8 μg m-3 in 2020.

‘Large-scale measures to improve air quality have potential to protect vulnerable people living with chronic asthma in urban areas,’ the authors concluded.

Commenting on the ‘unique situation’ of temporary air quality improvement, Dr Suzanne Bartington, clinical associate professor of environmental health at the University of Birmingham and lead author of the study, said: ‘The results of air pollution levels falling may have had an impact on the number of severe asthma cases that need acute hospital care, with 41% fewer hospital stays compared to the previous five-year average.

‘Furthermore, we also identified a 4% increase in risk of asthma hospital admissions for every 1 μg m-3 increase in mean monthly NO₂, and an approximately 3% increase in risk for every 1 μg m-3 increase in mean monthly PM2.5 levels.

‘This is an important study to help us better understand how demand for NHS inpatient care may change when air quality is improved.’

The research team was supported by the University of Oxford, Oxfordshire County and City Councils and the then Oxfordshire Clinical Commissioning Group.

Commenting on the results, Councillor Nathan Ley, Oxfordshire County Council’s cabinet member for public health, inequalities and community safety, said: ‘We must now use what we have learned, thanks to this research with our partners, to improve our environment, in line with the Clean Air Strategy which we launched last year.

‘Elevated levels of NO₂, PM_2.5 and PM₁₀ contribute towards heart disease, chronic lung disease, cancers, preterm births, and many other avoidable events. The vision of Oxfordshire County Council to tackle this issue remains clear. We must continue to use all the tools at our disposal to lead the country, clean up our air and save lives.’

Earlier this week, the European Respiratory Society (ERS) warned of rising respiratory diseases, such as asthma, as well as premature death without urgent action on air quality.

This followed the ERS consensus statement on climate change and respiratory health, published in September 2023, which highlighted the damaging effects of air pollution on health and global warming.

Dupilumab treatment provides greatest benefit among mAbs in moderate to severe asthma

13th April 2023

Dupilumab treatment produced the lowest incidence of asthma exacerbations and greatest improvements in FEV1 among three currently used mAbs

Dupilumab treatment for 12 months leads to the lowest number of exacerbations and better improvements in FEV1 compared to two commonly used monoclonal antibodies (mAbs), omalizumab or mepolizumab, in adults with moderate to severe asthma, according to comparative analysis by US researchers.

The prevalence of severe asthma varies between 3.6 and 6.1% of all patients with the disease. Individuals with moderate to severe asthma have the opportunity of being treated with several monoclonal antibodies, which target key inflammatory cytokines involved in disease pathogenesis. All of these currently approved biologic therapies have been shown to improve asthma-related outcomes in individuals with asthma uncontrolled with conventional therapy. However, for patients with more than one phenotype such as allergic and eosinophilic asthma, trying to identify the most suitable agent is less clear. In the absence of direct head-to-head comparative trials, researchers can often utilise observational data to emulate a hypothetical pragmatic randomised trial, which is referred to as the target trial.

In the current analysis, the research team emulated a hypothetical randomised trial, making use electronic health records from a large US-based academic health care system. They included adult participants with baseline IgE levels between 30 and 700 IU/mL and peripheral eosinophil counts of at least 150 cells/μL with the objective of comparing the effectiveness of dupilumab treatment with omalizumab or mepolizumab in patients with moderate to severe asthma. The main outcomes of interest were the incidence of asthma-related exacerbations and the change in baseline FEV₁ value over 12 months of follow-up.

Dupilumab treatment and asthma outcomes over 12 months

In all, 68 individuals received dupilumab treatment 68 received omalizumab and 65 received mepolizumab.

Over the 12 month period of follow-up, asthma-related exacerbations occurred in 25.0% of those receiving dupilumab treatment compared to 43.1% for mepolizumab (adjusted hazard ratio, aHR = 0.35, 95% CI 0.18 – 0.71). Compared to omalizumab group, asthma exacerbations occurred in 39.7% of patients, giving a corresponding adjusted hazard ratio of 0.42 (95% CI 0.20 – 0.87).

The change in FEV₁ for the different agents were 0.11 L (95% CI -0.003 to 0.222 L) for dupilumab versus mepolizumab and 0.082 L (95% CI -0.040 to 0.204 L) for dupilumab versus omalizumab.

In patients with eosinophil counts of at least 300 cells/μL, the HR for dupilumab compared to mepolizumab was 0.26 (95% CI 0.10 – 0.67) and 0.24 (95% CI 0.09 – 0.63) for dupilumab vs omalizumab.

Based on these findings, the authors concluded that among patients with asthma and eosinophil counts of at least 150 cells/μL and IgE levels of 30 to 700 kU/L, dupilumab was associated with greater improvements in exacerbation and FEV₁ value than either omalizumab or mepolizumab.

Citation
Akenroye AT et al. Comparative effectiveness of omalizumab, mepolizumab, and dupilumab in asthma: A target trial emulation. J Allergy Clin Immunol 2023