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.


CONCLUSIONS
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.
Department of Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands.
Mna
M
Van Steenis
NIVEL (Netherlands institute for health services research), Utrecht, The Netherlands.
Ja
J
Driesenaar
NIVEL (Netherlands institute for health services research), Utrecht, The Netherlands ; Department of Psychology, Faculty of Social and Behavioural Sciences, Utrecht University, Utrecht, The Netherlands.
Jm
J
Bensing
Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht University, Utrecht, The Netherlands.
R
R
Van Hulten
Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht University, Utrecht, The Netherlands.
Pc
P
Souverein
NIVEL (Netherlands institute for health services research), Utrecht, The Netherlands ; Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht University, Utrecht, The Netherlands.
L
L
Van Dijk
IQ Healthcare, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
Pagm
P
De Smet
NIVEL (Netherlands institute for health services research), Utrecht, The Netherlands ; Department of Primary and Community Care, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands ; Department of Health Sciences, Buskerud University College, Drammen, Norway.
Am
A
Van Dulmen
adherence; asthma; asthma symptoms; inhaled corticosteroids; medication beliefs