Gender differences in symptoms of severe asthma are substantially mediated by obesity and mood disorder, and as such should be considered as treatable traits of the disease, a UK respiratory medicine meeting has heard.
“Obesity and mood disorder are likely to be barriers to remission, and I think we should regard them as tractable, treatable traits”, said Professor Liam Heaney, a Professor of Respiratory Medicine at Queens University Belfast at the British Thoracic Society 2022 meeting in London last week.
“We have great tools to suppress T2 inflammation, now I think we need to identify these as traits and go after them,” said Prof Heaney, a Consultant Physician at Belfast City Hospital.
He said primary care data and the Severe Asthma Registry have shown that asthma control – no matter how it’s measured – is worse in females, who are more prone to exacerbations and unscheduled healthcare visits and are more likely to be obese, have depression or anxiety and be biomarker low.
Women are also more likely to be receiving maintenance oral corticosteroids, “the suggestion being that they’re getting a lot of maintenance oral corticosteroids to try and suppress this high symptom burden”, he added.
Findings of a new analysis of data, accepted for publication in the journal JACI in Practice, showed that women with severe asthma were much less likely than men to reduce treatment in a symptom-based study arm (10% versus 40%) because of a persistently high symptom burden, but no such difference was observed when treatment was biomarker-based.
In a subsequent mediation analysis, researchers found no impact on the gender divide when adjusting for age and smoking, but when adjusting for BMI and BMI and mood disorder, the difference between the genders with regard to symptom burden was removed.
“This suggests that high BMI, which we know is more common in this female population, and mood disorder are mediating, at least partly or substantially, this difference in ACQ,” Prof Heaney said.
Weight loss benefit
He also highlighted findings of a new small RCT, also presented at BTS Winter 2022, which showed a beneficial impact of a dietary programme on asthma symptoms and quality of life in adults with difficult-to-treat disease.
The team, led by Dr Varun Sharma, University of Glasgow, randomised patients with a body mass index (BMI) of 30kg/m2 to receive usual care or a structured low-energy formula diet replacement programme, which consisted of a 12-week total diet replacement phase (850kcal/day low-energy formula), followed by food reintroduction and weight loss maintenance.
The results, published in Thorax, showed that the programme yielded “significant improvements in asthma control and quality of life over 16 weeks, compared to usual care, in adults with difficult-to-treat asthma and obesity”.
Over 16 weeks, weight loss was greater in the intervention group versus usual care (mean difference -12.3kg, p<0.001), as was the mean change in ACQ6 (-0.4 versus 0.2, respectively, p=0.048), while a larger proportion of participants also had 0.5 improvement in ACQ6 (minimal clinically important difference) with the weight loss programme (53% vs 19%; p=0.041).
The findings indicate that this intervention “may be a generalisable treatment option for this challenging phenotype”, though longer term outcomes “continue to be studied”, the researchers noted.