Factors associated with medication adherence in patients with chronic obstructive pulmonary disease.

BACKGROUND: Predictors of medication adherence are not well known in chronic obstructive pulmonary disease (COPD). It is therefore necessary to identify factors associated with adherence to improve the effectiveness of COPD management within real-world situations.

OBJECTIVES: The goals of this study were to estimate adherence to respiratory medication and to identify factors related to adherence in COPD patients.

METHODS: This was an observational, cross-sectional study conducted on a sample of COPD outpatients. The following information was obtained: adherence to respiratory therapy (Morisky Medication Adherence Scale), age, gender, smoking status, COPD severity [Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage], lung function [post-bronchodilator forced expiratory volume in 1 s (FEV(1))], treatment regimen for COPD, COPD medication costs per month paid by the patient and health-related quality of life (EuroQol 5-dimension questionnaire). A multivariate logistic regression analysis was performed to identify the independent predictors of adherence.

RESULTS: Of the 170 participants (mean age 63.8 years, 41.8% male), 58.2% reported optimal adherence. Adherence to respiratory therapy was associated with age, current smoking status, number of respiratory drugs, number of daily respiratory drug doses and quality of life (p < 0.005). Adherence to respiratory therapy was not related to gender, GOLD stage, FEV(1) or COPD medication costs.

CONCLUSIONS: Adherence to COPD medication regimens is poor. Less frequent dosing regimens could be an effective method to enhance adherence to respiratory therapy. Quality-of-life monitoring within clinical practice settings could facilitate improved medication adherence.