Proportion of asthma patients who could benefit from anti-IL-5 treatment estimated
medwireNews: Researchers estimate that 2% of patients with adult-onset eosinophilic asthma could benefit from treatment involving antibodies against the interleukin-5 pathway (anti-IL-5).
The findings, based on data collected on 203 asthma patients at the 12-year follow-up of the Seinäjoki Adult Asthma Study, also indicate that not all anti-IL-5 eligible patients meet the criteria for severe asthma.
In all, 5.9% of patients had severe uncontrolled asthma according to the American Thoracic Society/European Respiratory Society Task Force definition. But overlap between severe asthma and anti-IL-5 treatment eligibility was seen in only one of the four patients. The remaining three did not meet the criteria for severe asthma because they were not receiving a high dose of inhaled corticosteroid (ICS).
“Despite not belonging to the group of [severe asthma], all anti-IL-5-treatable patients fulfilled 1 or more features of uncontrolled asthma,” note Pinja Ilmarinen (Seinäjoki Central Hospital, Finland) and fellow researchers.
They found that both groups of patients “are a high burden to health care, suggesting that the current treatments are ineffective for these patients.”
This highlights the need to “identify these phenotypes as early as possible because they may benefit from targeted treatment that could lower long-term use of healthcare,” the team stresses.
Eligibility for anti-IL-5 treatment was based on three criteria: daily use of a medium-to-high inhaled ICS dose and long-acting β2-agonist; at least two exacerbations in the previous year; and a blood eosinophil count of 300 cells/µL or fraction of exhaled nitric oxide of 50 ppb or above.
The patients meeting these criteria differed from patients with severe asthma in being less likely to smoke and be obese, using lower doses of ICS, and having a lower blood neutrophil count 12 years after diagnosis, the team reports in The Journal of Allergy and Clinical Immunology: In Practice.
The two groups of patients were alike, however, in visiting hospital more often due to their asthma – either all or unplanned – than patients with non-severe asthma.
Patients eligible for anti-IL-5 treatment accounted for 4.7% of all asthma-related visits to healthcare and 7.9% of unplanned visits, which is two- to fourfold higher than would normally be expected, the team reports.
For patients with severe asthma, the percentages were 13% and 13.9%, respectively, equating to double what would be expected.
The researchers note that the biggest difference between the two groups was in the number of hospitalizations, with patients eligible for anti-IL-5 treatment accounting for just 2%, while patients with severe asthma accounted for 31% – fivefold more than expected.
Recognizing that the small number of patients poses a major limitation of the study, the researchers used bootstrap analysis to estimate the 95% confidence interval for the 2% prevalence and report that it was “relatively narrow” at 0.5% to 4.1%.
By Lucy Piper
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