Age and asthma severity affect corticosteroid response
medwireNews: Asthma may be more resilient to treatment as patients become adults, but one in five of those with severe disease can still expect lung function improvement following systemic corticosteroid administration, say researchers.
Among 526 adults aged 18 years and older and 188 children aged 6 to 18 years, 315 and 107, respectively, had severe poorly controlled asthma with airflow obstruction despite treatment with inhaled or oral corticosteroids, as defined by 2014 American Thoracic Society/European Respiratory Society guidelines.
The researchers found that adults and children responded differently to a single dose of intramuscular triamcinolone acetonide (40 mg in adults and up to 40 mg maximum in children), depending on the severity of their disease.
An average 18 days after administration, fractional exhaled nitric oxide (FeNO) and sputum eosinophil levels declined in adults with severe and non-severe disease, making pretreatment differences no longer significant. However, significant differences in airflow obstruction (bronchodilator forced expiratory volume in 1 second [FEV1] % predicted) and symptom scores on the Asthma Control Questionnaire-6 score persisted.
By contrast, in children, corticosteroid administration lessened the significant differences in airflow obstruction and eliminated the differences in symptom scores between children with severe and non-severe disease. The researchers also note that once bronchodilators were administered, airway function in children with severe asthma was already indistinguishable from that in children with non-severe disease.
“The difference in persistence of the [severe asthma] phenotype after corticosteroids and bronchodilators in adults and children is interesting and suggests that as patients move to adulthood their asthma may be a less reversible disease,” say Wanda Phipatanakul (Harvard Medical School, Boston, Massachusetts, USA) and co-researchers.
The team adds that the “equalizing” dose of systemic corticosteroid suggests that the features of severe asthma are not simply related to poor use of, or adherence to, corticosteroid treatment.
Encouragingly, however, the researchers report in the American Journal of Respiratory and Critical Care Medicine that one in five children or adults with severe asthma experienced at least a 10% improvement in FEV1 with intramuscular corticosteroid despite already receiving inhaled or oral corticosteroid treatment.
Spirometry-measured response to bronchodilator treatment at baseline was the strongest predictor of a corticosteroid response for all groups, except children with non-severe asthma, with accuracy rates of 77% and 70% for adults with non-severe and severe asthma, respectively, and 74% for children with severe disease.
But FeNO an indicator of type 2 inflammation was also a good predictor, particularly in adults with severe asthma, accurately predicting a response in 68% of cases, making it as good as or better than blood or sputum eosinophils.
In post-hoc subgroup analysis, patients with severe asthma and FeNO levels of 20 ppb or above were three times more likely to respond to the corticosteroid than those with lower levels.
This finding lends “further evidence that elevated FeNO may identify a subset of severe asthmatic patients who may benefit from additional systemic therapy targeting Type 2 inflammation,” the team concludes.
By Lucy Piper
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