Adherence to inhaled therapies, health outcomes and costs in patients with asthma and COPD.

Suboptimal adherence to pharmacological treatment of asthma and chronic obstructive pulmonary disease (COPD) has adverse effects on disease control and treatment costs. The reasons behind non-adherence revolve around patient knowledge/education, inhaler device convenience and satisfaction, age, adverse effects and medication costs. Age is of particular concern given the increasing prevalence of asthma in the young and increased rates of non-adherence in adolescents compared with children and adults. The correlation between adherence to inhaled pharmacological therapies for asthma and COPD and clinical efficacy is positive, with improved symptom control and lung function shown in most studies of adults, adolescents and children. Satisfaction with inhaler devices is also positively correlated with improved adherence and clinical outcomes, and reduced costs. Reductions in healthcare utilisation are consistently observed with good adherence; however, costs associated with general healthcare and lost productivity tend to be offset only in more adherent patients with severe disease, versus those with milder forms of asthma or COPD. Non-adherence is associated with higher healthcare utilisation and costs, and reductions in health-related quality of life, and remains problematic on an individual, societal and economic level. Further development of measures to improve adherence is needed to fully address these issues.