Relationship between medication beliefs, self-reported and refill adherence, and symptoms in patients with asthma using inhaled corticosteroids

BACKGROUND Beliefs play a crucial role in medication adherence. Interestingly, the relationship between beliefs and adherence varies when different adherence measures are used. How adherence, in turn, is related to asthma symptoms is still unclear. Our aim was to investigate the relationship between beliefs (ie, necessities and concerns) about inhaled corticosteroids (ICS) and subjectively as well as objectively measure adherence and the agreement between these measures. Further, the relationship between adherence and asthma symptoms was examined. METHODS A total of 280 patients aged 18-80 years who filled at least two ICS prescriptions in the preceding year were recruited to complete a questionnaire. The questionnaire included the Beliefs about Medicines Questionnaire to assess necessity beliefs and concerns about ICS, four questions about ICS use to measure self-reported adherence, and the Asthma Control Questionnaire to assess asthma symptoms. Proportion of days covered was used to determine pharmacy refill adherence. RESULTS Data from 93 patients with asthma were analyzed. Necessities were positively related to self-reported adherence (P = 0.01). No other associations were found between beliefs and subjective or objective adherence. There was no correlation between self-reported and refill adherence. Participants were significantly (P < 0.001) less adherent according to self-report data (24.4%) than according to pharmacy data (57.8%). No relationship was found between adherence and asthma symptoms. CONCLUSION Higher necessities are associated with higher self-reported adherence, suggesting that it could be more important to focus on necessities than on concerns in an attempt to improve adherence. Self-reported and refill adherence measurements cannot be used interchangeably. No relationship between adherence and asthma symptoms was found.