Exploring the relationship between health beliefs and medication adherence in individuals with asthma

Foot, Holly (2016). Exploring the relationship between health beliefs and medication adherence in individuals with asthma PhD Thesis, School of Pharmacy, The University of Queensland. doi:10.14264/uql.2017.60

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Author Foot, Holly
Thesis Title Exploring the relationship between health beliefs and medication adherence in individuals with asthma
School, Centre or Institute School of Pharmacy
Institution The University of Queensland
DOI 10.14264/uql.2017.60
Publication date 2016-12-21
Thesis type PhD Thesis
Supervisor Neil Cottrell
Adam La Caze
Gina Gujral
Peter Baker
Total pages 216
Language eng
Subjects 1701 Psychology
1115 Pharmacology and Pharmaceutical Sciences
Formatted abstract
In individuals with asthma, non-adherence to inhaled corticosteroids contributes to increased exacerbations, healthcare utilisation and mortality. Understanding the beliefs an individual holds about their medicines, illness and about the controllability of their health provides a promising way to better understand non-adherence in individuals with chronic conditions. Research to date has focussed on bivariate relationships between a specific set of beliefs and medication adherence. This approach simplifies the complex, multifaceted nature of medication adherence. I suggest that investigating how different beliefs associate with medication adherence in a multivariable model may improve understanding of adherence decisions.

The aim of the thesis is to investigate the relationship between beliefs about medicines, illness perceptions and locus of control beliefs with self-reported medication adherence in individuals with asthma.

The first part of the thesis was to identify whether beliefs about medicines, elicited through the Beliefs about Medicines Questionnaire (BMQ), were correlated to medication adherence on a population level. The BMQ consists of two scales that seek to elicit an individual’s beliefs in the necessity and concerns of taking medication. Necessity beliefs reflect medicines being protective of current and future health and concern beliefs reflect beliefs about the negative effects of medicines. Beliefs about medicines are thought to play a key role in medication-taking, but inconsistent results across different conditions and different measures of adherence makes it difficult to conclude the size of the effect at a population level. A meta-analysis was conducted to identify whether beliefs in the necessity and concerns of medicines, were significantly correlated with medication adherence across different conditions. An electronic search was conducted for manuscripts comparing scores from the BMQ to measures of medication adherence. Studies were pooled using the random-effects model to produce a mean effect size correlation. Studies were stratified for condition, adherence measure, power and study design. Ninety-four papers were included and the overall effect size correlation was 0.17 for necessity and -0.18 for concerns (p<0.0001). Necessity and concerns beliefs were correlated with medication adherence on a population level and across the majority of included conditions. The effect sizes were small with a magnitude comparable to other predictors of adherence. Exploring the role of beliefs outside the Beliefs about Medicines Framework may improve prediction and understanding of medication adherence.

A cross-sectional study was conducted to explore the relationship between measures of health beliefs and medication adherence in individuals with asthma. A total of 198 participants using a preventative asthma inhaler for three or more months were recruited from two community pharmacies and via online advertisement. Each participant completed a survey of validated questionnaires consisting of: BMQ, Brief Illness Perception Questionnaire (B-IPQ) and the Multi-dimensional Health Locus of Control Scale (MHLCS). Medication adherence was elicited using the Medication Adherence Report Scale (MARS) and the Asthma Readiness to Change Questionnaire.

There was a range of beliefs and medication-taking behaviours reported in this sample. We found that the mean scores on BMQ, B-IPQ and MHLCS subscales were different compared to studies conducted in other chronic conditions, suggesting that interventions to support medication adherence in asthma may need to be different to interventions used in other chronic conditions.

Multivariable regression analysis with interaction effects was performed to discover the interrelationships between beliefs and the ways in which these interrelationships may better predict adherence behaviour. The identified regression model predicted 39% of the variance in MARS score (p<0.0001). Predictors of better medication adherence were: strong necessity beliefs and few concerns about medicines (BMQ); perceiving a shorter timeline of asthma (B-IPQ) and; believing the doctor to control asthma outcomes (MHLCS). The doctor (MHLCS) subscale was the strongest predictor and accounted for the most variance (12%) in adherence scores. There were two significant interactions between belief scales: concerns (BMQ) scale interacting with chance (MHLCS) scale and understanding (B-IPQ) scale with treatment control (B-IPQ) scale. The results of the regression model supports eliciting multiple beliefs and exploring interaction effects as beliefs about medicines, illness perception and locus of control beliefs all made unique contributions to model prediction and incorporating interaction effects improved prediction of medication adherence.

To identify beliefs that may be amenable to an intervention to improve adherence, I explored the degree to which the regression model could be given a causal interpretation. Using an interventionist account of causation, I suggest that improving necessity beliefs about medicines and treatment control illness perceptions, reducing concern beliefs about medicines are a strategy to improve medication adherence. Doctor locus of control beliefs appear to be causally related to adherence, but these beliefs may difficult to intervene upon.

In conclusion, this thesis contributes to the literature by determining the relationship between beliefs about medicines, illness perceptions and locus of control beliefs with medication adherence in individuals with asthma. Exploring the causal relationship between beliefs and medication adherence has provided hypotheses that can be tested in the future.
Keyword Medication adherence
Medication beliefs
Illness perceptions
Locus of control beliefs
Health behaviour models

Document type: Thesis
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Created: Sat, 17 Dec 2016, 00:30:15 EST by Holly Ross on behalf of Learning and Research Services (UQ Library)