The high burden of asthma appears to be related to poor asthma control, which is associated with more frequent asthma symptoms, greater bronchodilator use and functional impairment, and worse pulmonary function. Despite the availability of effective treatments, more than 58% of asthmatics are poorly controlled. Daily adherence to inhaled corticosteroid (ICS) regimens is considered by experts to be one of the most important behavioral factors linked to achieving optimal asthma control. However, there is a paucity of research on interventions specifically designed to improve ICS adherence among adult asthmatics. The vast majority of intervention studies to date used atheoretical interventions to target behavior change, relying mainly upon educational approaches which have been criticised for "failing to translate knowledge into action." This may be due to the fact that most education-based approaches do not specifically address or help patients overcome ambivalence about behavior change, which is necessary for ensuring daily adherence. Motivational interviewing (MI) is a client-centred intervention that focuses on enhancing intrinsic motivation to change a particular behavior, and exploring and resolving ambivalence about behavior change. Brief MI sessions (e.g., 1-5 x 15-30 minute sessions) have been shown to improve a variety of health behaviors (e.g., reduce alcohol consumption, improve dietary habits, increase exercise behaviour, and improve medication adherence) and health outcomes (reduce blood pressure, body mass index, and cholesterol levels). However, no studies to date have assessed the efficacy of using MI to improve ICS adherence in asthmatics. This study aims to assess the efficacy of using MI to improve daily medication (ICS) adherence in a sample of poorly controlled, non-adherent asthmatics. It is hypothesized that patients randomized to the MI condition will exhibit significantly improved ICS adherence at 6 and 12-months post-intervention, independent of baseline levels and covariates, relative to patients randomized to the usual care control condition.

Inclusion Criteria:

• Patients 18 years and older
• Primary diagnosis of moderate-severe persistent asthma (as per GINA)
• Prescribed inhaled corticosteroid medication (min dose of 250 µg fluticasone equivalent per day) for at least 12 consecutive months
• Uncontrolled asthma (≤ 19 on the Asthma Control Test)
• Covered by a drug insurance plan (e.g., RAMQ)
• Non-adherent to ICS medication (based on having filled less than 30% of their prescriptions over the last year)
• Able to speak English or French.

Exclusion Criteria:

• Any other medical condition that confers greater illness morbidity than asthma (e.g., active cancer)
• Severe psychopathology (e.g., schizophrenia)
• Apparent cognitive or language deficit
• Are or plan to become pregnant or move outside of Quebec over the course of the study.