Nonadherence to inhaled corticosteroids (ICS) is common in patients with severe eosinophilic asthma (SEA) receiving mepolizumab and is associated with fewer reductions in oral corticosteroid (OCS) requirements and annualized exacerbation rate (AER), according to study results published in the European Respiratory Journal.

Although most patients with asthma achieve disease control with ICS, adherence is often poor, and patients with SEA may require additional treatment with OCS and/or biologics such as mepolizumab. To examine whether ICS adherence affects clinical response to biologic therapy, study investigators examined adherence and clinical outcomes in OCS-dependent participants with SEA who completed 1 year of mepolizumab therapy. The researchers calculated the ICS medicines possession ratio (MPR) (the number of doses of ICS issued on prescription/expected number) for the year before and after initiation of the biologic and defined good adherence as an MPR ≥0.75, intermediate as an MPR from 0.74 to 0.51, and poor as <0.5. Investigators examined outcomes after 12 months of therapy with mepolizumab, including reductions in OCS and AER, stratified by ICS adherence on mepolizumab.

Of 109 enrolled participants who commenced treatment with mepolizumab from April 2017 to June 2018, 91 completed 12 months of treatment and had prescription records available. Participants required a median daily 10 mg dose of prednisone (interquartile range [IQR], 10-15) but still had poorly controlled asthma. At baseline, 22% of participants had poor ICS adherence, with an MPR of <0.5 over the previous 12 months. Over 12 months of therapy with mepolizumab, 68% (n=62) of participants maintained good ICS adherence, and 32% (n=29) had moderate or poor adherence. Participants with poor ICS adherence were more likely to be smokers and to have had poor adherence at baseline. Overall ICS use levels remained similar after mepolizumab initiation, with the mean baseline ICS MPR being 0.81±0.32 compared with 0.82±0.32 on mepolizumab (P =.786).

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Mepolizumab treatment led to significant clinical outcome improvements across the cohort, with 52% of participants being able to completely stop OCS. Non–ICS-adherent participants had lesser OCS dose reductions than participants with good ICS adherence (median percentage OCS dose reduction 60 [IQR, 27-100] vs 100 [IQR, 74-100]; P =.031).

ICS-adherent patients had a 66% mean AER reduction, from 3.2±2.9 events to 1.1±1.4 events (P <.001) compared with participants with intermediate or poor adherence, who experienced no AER reductions (P =.004).

In participants adherent to ICS, the odds ratio for cessation of OCS was 2.8 (95% CI, 1.1-7.1; P =.027). After adjustments for possible confounders, ICS adherence and baseline OCS dose remained associated with the likelihood of OCS cessation (adjusted odds ratio, 3.19; 95% CI, 1.02-9.94; P =.045). Of the participants, 14.3% (n=13) experienced treatment failure, defined as an inability to reduce exacerbation frequency or ICS by ≥50%. Poor ICS adherence was more common in these participants than in participants who benefited from mepolizumab (46.2% vs 12.8%; P =.011).

Study investigators concluded, “Our data highlight the need for healthcare professionals caring for SEA patients treated with biologic therapies to re-assess and address ICS adherence, particularly in the context of any apparent failure of biologic therapy.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


d’Ancona G, Kavanagh J, Roxas C, et al. Adherence to inhaled corticosteroids and clinical outcomes in mepolizumab therapy for severe asthma [published online February 20, 2020]. Eur Respir J. doi:10.1183/13993003.02259-2019