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Scientists comment on an unpublished study presented at the European Respiratory Society Congress about semaglutide and asthma attacks in people with diabetes
Dr Marie Spreckley, Researcher on the Prevention of Diabetes and Related Metabolic Disorders at the University of Cambridge, said:
“The title ‘semaglutide can reduce asthma attacks’ makes a causal claim that is not supported by this observational study. The study identifies an association between semaglutide use and a lower hazard of airway exacerbations, but it cannot establish that semaglutide caused this difference. A more accurate title would be ‘Semaglutide use associated with fewer asthma attacks’.
“This is a large and potentially important real-world study that adds to growing evidence of an association between GLP-1 receptor agonist use and better respiratory outcomes. The new-user, active-comparator design is a strength, and the researchers appear to have adjusted for several important factors, including body mass index, smoking, disease severity, eosinophil levels and comorbidities.
“However, this remains an observational study and cannot establish that semaglutide itself caused the apparent reduction in exacerbations. People prescribed semaglutide may differ from those prescribed sulfonylureas in ways that are not fully captured in routine health records, including the reasons for receiving a particular medicine, their wider clinical care and their treatment adherence. These differences could account for at least part of the observed association.
“The asthma estimate is striking but imprecise. The reported hazard ratio of 0.20 corresponds to an estimated 80% lower hazard, but the confidence interval is wide and is compatible with a much smaller benefit. The evidence of a dose-response relationship should also be interpreted cautiously because the confidence interval for the higher-dose estimate includes the possibility of no difference.
“All participants were receiving treatment for type 2 diabetes, so the findings cannot automatically be generalised to people using semaglutide solely for weight management. The authors’ analysis according to weight loss is interesting, but it does not prove that the association is independent of weight loss or establish another biological mechanism.
“The most defensible conclusion is that semaglutide use was associated with a lower hazard of airway exacerbations in this dataset, particularly among people with asthma. It is too early to state that semaglutide reduces or prevents asthma attacks. People should not seek semaglutide specifically for asthma or change their existing asthma treatment because of these findings. Randomised trials are needed to determine whether semaglutide provides a genuine respiratory benefit.”
Prof Stephen Burgess, Professor of Biostatistics at the University of Cambridge, said:
“This is a summary of an upcoming conference presentation rather than a full scientific paper, and so we cannot be clear exactly what analyses the researchers performed. However, the methods that were used are well-established, and so we can comment with a reasonable degree of confidence on the strengths and weaknesses of the approaches used in this research, even if we cannot comment specifically about the analyses performed.
“As the researchers state, this is an observational study, and so it can provide supportive evidence for an effect, but not conclusive evidence. The findings are suggestive of a beneficial effect of semaglutide, a specific weight loss drug, on airway exacerbations. The hypothesis that obesity has a harmful effect on asthma risk has been supported by previous research, and so this finding is welcome.
“The researchers are generally clear when presenting the findings of their work and the level of evidence that it provides. An exception to this is the heading of the press release, which states that ‘semaglutide can reduce asthma attacks’. This claim is not reasonable – it cannot be established with any level of certainty based on this study. Clinical trials will be needed to validate this claim.
“Other weight loss drugs that are GLP-1 receptor agonists are reported to not show evidence of benefit, but the exact estimates are not provided by the researchers. It is not clear if the beneficial finding for semaglutide and lack of beneficial findings for other similar drugs is a true indicator of a specific effect, or a statistical anomaly – a chance finding. It may simply be that we can make a stronger claim about semaglutide because we have more data on this drug.
“Asthma is a complex disease, and so it is possible that not all asthma types are affected by weight loss. It is also possible that not all individuals with asthma would benefit from weight loss. Clinical trials estimate average effects across the population, which are representative of overall trends rather than predictions of benefit for each individual. Still, GLP-1 receptor agonists can lead to life-changing reductions in body weight, and so it is both logical and heartening that we see evidence for beneficial effects on conditions that are hypothesized to be consequences of obesity.”
Dr Samantha Walker, Director of Research and Innovation at Asthma + Lung UK, said:
“This promising study indicates that people already taking semaglutide for a condition such as diabetes experience a significant reduction in asthma attacks and COPD flare ups. The positive effects of semaglutide were significant for patients with asthma and COPD compared with other GLP-1 agnostics, with a stronger association in asthma. These exciting findings build on research funded by Asthma + Lung UK, using existing health data to improve our understanding of lung health treatments. For people with asthma living with conditions like diabetes, this is a promising step forward in helping to treat their lung health.
“This is an observational study so further clinical trials will be required to better understand the exact mechanisms behind how semaglutide might reduce asthma and COPD exacerbations. Importantly, this study only links a reduction in flare-ups for people taking semaglutide for other conditions like diabetes, who also have asthma or COPD. The findings do not apply to people with asthma or COPD who do not have those co-morbid conditions.
“Cutting edge research like this is vital to improve the health and lives of people with lung conditions but funding for lung health research is on life support. While lung conditions remain the third biggest cause of death in the UK, we need urgent action to boost research investment and improve health outcomes.”
Declared interests
Prof Stephen Burgess: “I have no relevant conflict of interest to declare.”
Dr Marie Spreckley “is a Postdoctoral Researcher at IMS Epidemiology, University of Cambridge, where her research focuses on obesity, nutrition and incretin-based therapies. She has no personal financial interests, consultancy roles, advisory positions, speaker fees, stock ownership, or honoraria from manufacturers of GLP-1 or GIP/GLP-1 receptor agonists.”
For all other experts, no reply to our request for DOIs was received.