Efficacy of a multifactorial intervention on therapeutic adherence in patients with chronic obstructive pulmonary disease (COPD): a randomized controlled trial

The study design consisted of a randomised controlled trial in a primary care setting. 146 patients diagnosed with COPD were randomly allocated into two groups using the block randomisation technique. One-year follow-ups with three visits were performed. The intervention consisted of motivational aspects related to adherence (beliefs and behaviour) in the form of group and individual interviews, cognitive aspects in the form of information about the illness and skills in the form of training in inhalation techniques. Cognitive-emotional aspects and training in inhalation techniques were reinforced during all visits of the intervention group. The main outcome measure was adherence to the medication regimen. Therapeutic adherence was determined by the percentage of patients classified as good adherent as evaluated by dose or pill count.

Of the 146 participants (mean age 69.8 years, 91.8% males), 41.1% reported adherence (41.9% of the control group and 40.3% of the intervention group). When multifactorial intervention was applied, the reported adherence was 32.4% for the control group and 48.6% for the intervention group, which showed a statistically significant difference (p = 0.046). Number needed to treat is 6.37. In the intervention group, cognitive aspects increased by 23.7% and skilled performance of inhalation techniques increased by 66.4%. The factors related to adherence when multifactorial intervention was applied were the number of exacerbations (OR = 0.66), visits to health centre (OR = 0.93) and devices (OR = 2.4); illness severity (OR = 0.67), beta-2-adrenergic (OR = 0.16) and xantine (OR = 0.19) treatment; activity (OR = 1.03) and impact (OR = 1.03) scales of the Saint George Respiratory Questionnaire.