Keywords: adherence, asthma, inhalers

Background:

Inhalers containing bronchodilators and corticosteroids are the cornerstone of asthma therapy. Adherence to prescribed medication is critical to successful management.

Research questions:

To study inhaler adherence in a large cohort of asthma patients, and to assess the effect of a specific inhaler on adherence.

Method:

We conducted a retrospective cohort study at Clalit Health Service (CHS), an HMO serving >50% of the Israeli population. CHS members aged 40-80 years with a diagnosis of asthma, who filled ≥1 prescription/year 2017-2019 (regular users) for at least one inhaler containing inhaled corticosteroids (ICS), long-acting beta-adrenergics (LABA), and/or long-acting anti-muscarinics (LAMA) were included. Filled monthly prescriptions were used as a proxy for actual medication use. The primary endpoint was the proportion of adherent users (defined as purchasing≥3 inhalers/yr in 2018).

Results:

45,801 asthma patients (age 68.4±7.1 yrs., 45% men, 40% ever smokers) were identified. 18,568 were regular inhaler purchasers (40% of total). 99% of the patients got inhalers containing steroids, and 93% got combination inhalers with both steroids and LABA. 95.7% used only one inhaler from the study inhalers. Adherence rates varied across inhalers, ranging from 51% to 77% among patients who purchased them for at least 3 months.
In multivariate analysis, adherence increased with age. Men and smokers were more likely to be adherent. Patients with good adherence were more likely to get oral steroids OR=1.09 (1.06, 1.12), and less likely to visit ER during 2018 OR=0.89 (0.83, 0.97). There was no difference in hospitalizations between more and less adherent patients.

Conclusions:

Asthma adherence rates are low and vary by inhaler type.
It seems that many asthma patients do not receive appropriate
inhaler treatment. Interventions are required to improve patient care.

Points for discussion:

Adherence in asthma patients

What affect adherence to inhalers

what do we need to do with the low adherence rates