adherence to inhaled medication in copd: predictors and outcomes
Kirsten Koehorst-ter Huurne is a PhD student in the research group Methodology, Measurement and Data Analysis (OMD). Her supervisor is prof.dr. J.A.M. van der Palen from the faculty Behavioural, Management and Social Sciences.
This thesis describes therapy adherence to inhaled medication in COPD based on data of the “Cohort of Mortality and Inflammation in COPD” (COMIC) study, a single centre prospective cohort study in the Medisch Spectrum Twente hospital, Enschede. From December 2005 till April 2010, 795 patients were included with a follow-up period of three years. In order to investigate therapy adherence four adherence categories were introduced, optimal (75-125%), suboptimal (50-<75%), underuse (<50%), and overuse (>125%).
Therapy adherence in COPD was related to the type of inhaled medication and inhalation device and was inversely related to lung function. Higher lung function was a predictor for suboptimal adherence and underuse. A lower lung function, anxiety for dyspnea, and current smoking were predictors for overuse.
Non-adherent inhaled corticosteroid (ICS) users had little knowledge of COPD and how to manage their COPD, including a lack of knowledge about the mechanisms of action of medication, and when which medication should be used. Underusers claimed using less medication because they felt well, did not want to use too much medication and used their inhalation devices too long after they were empty. Overusers reported medication “dependency” in the sense that they tended to catastrophize when being without medication and discarded inhalation devices too early because they feared to run out of medication.
Non-adherence with tiotropium was associated with an increased risk of having a severe COPD exacerbation that needs a hospitalization (AECOPD) and time to first community acquired pneumonia (CAP) compared to optimal use. Suboptimal and underuse of ICS and tiotropium were associated with a substantially increased mortality risk compared to optimal use, with even higher risks in underusers than suboptimal users.
It seems that inhalation therapy in COPD is too complex. Every patient should receive a tailored advice and interventions that are developed to improve adherence. Local pharmacists can play an important role in integrated COPD patient care.
