Identification of factors involved in medication compliance: incorrect inhaler technique of asthma treatment leads to poor compliance

OBJECTIVE: To identify the impact of delivery device of inhaled corticosteroids and long-acting β(2)-agonist (ICS/LABA) on asthma medication compliance, and investigate other factors associated with compliance. MATERIALS AND METHODS: We conducted a retrospective and multicenter study based on a review of medical registries of asthmatic patients treated with ICS/LABA combinations (n=2,213) whose medical devices were either dry powder inhalers (DPIs, such as Accuhaler(®), Turbuhaler(®), and NEXThaler(®)) or pressurized metered-dose inhalers (pMDI). Medication compliance included persistence outcomes through 18 months and medication possession ratios. Data on potential confounders of treatment compliance such as asthma exacerbations, comorbidities, demographic characteristics, and health care resource utilization were also explored. RESULTS: The probability of asthma medication compliance in case of DPIs was lower compared to pMDIs, which suggests that inhaler devices influence inhalation therapies. There were additional confounding factors that were considered as explanatory variables of compliance. A worse measure of airflow obstruction (forced expiration volume in 1 second), comorbidities and general practitioner (GP) consultations more than once per month decreased the probability of compliance. Within comorbidities, alcoholism was positively associated with compliance. Patients of 29–39, 40–50, and 51–61 age groups or suffering from more than two exacerbations during the study period were more likely to comply with their medication regime. The effects of DPIs toward compliance varied with the different DPIs. For instance, Accuhaler(®) had a greater negative effect on compliance compared to Turbuhaler(®) and Nexthaler(®) in cases of patients who suffered exacerbations. We found that GP consultations reduced the probability of medication compliance for patients treated with formoterol/budesonide combination. For retired patients, visiting the GP increased the probability of medication compliance. CONCLUSION: We concluded that inhaler devices influence patients’ compliance for long-term asthma medication. The impact of Accuhaler(®), Turbuhaler(®), and NEXThaler(®) on medication compliance was negative. We also identified some confounders of medication compliance such as patient’s age, severity of asthma, comorbidities, and health care costs.