Specific, but not general beliefs about medicines are associated with medication adherence in patients with COPD, but not asthma: Cohort study in a population of people with chronic pulmonary disease

Background: Beliefs about medicines are regarded as influencing factors on medication adherence (Horne, 1997). Adherence levels in patients with chronic pulmonary diseases are low (Bourbeau and Bartlett, 2008; Sumino and Cabana, 2013). A better understanding of the predictive role of patients' beliefs about medicines for adherence might be a crucial step to improve medication adherence.

Objective: This prospective study investigated the association between beliefs about medicines and medication adherence in patients with asthma and COPD.

Methods: The Beliefs about Medicines Questionnaire (BMQ) and the Medication Adherence Rating Scale (MARS) were administered to 402 patients (49% asthma, 51% COPD, 50% female, mean age 56.7 years (SD = 15.9)) at baseline. Follow-ups were carried out after 3 (N = 255) and 12 months (N = 171). Multivariable logistic regression analyses were performed analysing the association between the BMQ subscales at baseline and adherence at each follow-up inquiry. Sociodemographic, psychosocial, and disease related factors were considered as potential confounders.

Results: One third of the patients showed adherent behavior (18% and 46% of people with asthma and COPD). In the COPD sample, the subscale Specific-necessity showed a significant positive association with adherence at the 3-months-follow-up (OR = 2.6, 95% CI 1.4-5.1) and the subscale Specific-concerns showed a significant inverse association with adherence at the 3-months-follow-up (OR = 0.6, 95% CI 0.3-0.95) and the 12-months-follow-up (OR = 0.4, 95% CI 0.2-0.8). No significant association was found for the asthmatic sample.

Conclusions: Beliefs about medicines are important factors predicting future medication adherence in patients with COPD, but not asthma. Physicians should primarily focus on the specific beliefs of their patients in order to diminish medication non-adherence.