Original articlesPatients' beliefs about prescribed medicines and their role in adherence to treatment in chronic physical illness
Introduction
The appropriate use of medication is key to the self-management of most chronic illnesses. However, it is estimated that over 30% of prescribed medication is not taken as directed [1]. If the prescription was appropriate, then this represents a lost opportunity for health gain and a waste of resources [2]. A recent review called for more fundamental and applied research to improve our understanding of the causes of nonadherence and to develop interventions to help patients to get the best from their medicines [3].
Developments in health psychology have resulted in several theoretical models for understanding variations in adherence to treatment [4]. Social cognition models [5] and the self-regulatory theory [6] share the common assumption that individuals develop beliefs that influence the interpretation of information and experiences and which guide behavior [7]. Social cognition models, such as the health belief model [8] and the theory of planned behavior [9], have been used widely in studies exploring adherence to preventive health advice and to treatment recommendations in acute illnesses [5]. However, fewer studies have explored adherence in chronic illness utilizing this approach. These include the use of the theories of reasoned action and planned behavior to explain variations in medication adherence in bipolar effective disorders [10] and hypertension [11], and the health belief model in hypertension [12], diabetes [13], kidney disease [14], and psychiatric disorders [15]. These studies have produced a mixed pattern of findings. For example, adherence was typically predicted by various combinations of individual components of the health belief model, rather than by the precise interaction of variables specified by the model [4]. Studies involving the theories of reasoned action and planned behavior provide broad support for the assertion that behavioral intentions are influenced by attitudes and subjective norms, although the strength of the relationship between intentions and behavior varies across studies and between behaviors [16].
Despite a cogently argued rationale for the study of illness representations as determinants of treatment adherence [17], relatively few studies have adopted this approach. However, there is some empirical support for the utility of self-regulatory theory in explaining adherence decisions. Illness representations have been related to medication adherence in hypertension [18], and regimen adherence in diabetes [19]. In a recent prospective study, adherence to recommendations to attend rehabilitation classes following a first myocardial infarction was predicted by illness representations elicited during hospital convalescence [20].
In addition to examining the role of patients' beliefs about their illness as possible determinants of adherence to medication, a few studies have attempted to investigate patients' beliefs about their treatment, particularly their views about medicines. Earlier qualitative studies have shown that people have beliefs about medicines in general [21], as well as beliefs about medication prescribed for specific illnesses such as epilepsy [22] and hypertension [23]. Moreover, certain representations of medicines appear to be common across several illness and cultural groups. However, a systematic comparison of findings is hampered because few studies that have quantitatively assessed medication beliefs have used different questionnaires 24, 25 or have investigated medication beliefs in the broader context of views about the practice of medicine [26]. Furthermore, some studies have assessed peoples' ideas about medicines in general (general beliefs), whereas others have focused on specific medication prescribed for a particular illness (specific beliefs).
A recent study involving over 1200 participants, representing a range of chronic illness groups, showed that patients' beliefs about the specific medication prescribed for them (specific medication beliefs) could be grouped under two core themes. These were their beliefs about the necessity of the prescribed medication for maintaining health now and in the future, and concerns about the potential adverse effects of taking it (e.g., becoming too dependent on the medication or that regular use would lead to long-term adverse effects) [27]. Commonly held beliefs about medicines in general were also grouped under two themes. These included general beliefs about the intrinsic nature of medicines and the extent to which they are perceived as essentially harmful substances that should be avoided if possible, and general beliefs about the way in which medicines are used by doctors. This work has resulted in a new validated questionnaire-based method for the quantitative assessment of beliefs about medication [27].
A theoretical framework has been proposed to explain how these beliefs might influence patients' decisions about using prescribed medication [28]. It is thought that, although beliefs about medicines in general influence the patient's initial orientation toward medicines adherence behavior is likely to be more strongly related to personal views about the specific prescribed medication. In particular, it is proposed that adherence decisions are influenced by a cost–benefit assessment in which personal beliefs about the necessity of the medication for maintaining or improving health are balanced against concerns about the potential adverse effects of taking it.
The first aim of the present study was to describe the distribution of beliefs about the necessity of prescribed medication and concerns about taking it among patients from a range of chronic illness groups, using the newly developed Beliefs about Medicines Questionnaire (BMQ) [27]. A further aim was to determine whether patients' beliefs about their medicines influenced the way they used them; in particular, whether medication beliefs were more powerful predictors of adherence than demographic factors (age, gender, and educational experience) and clinical factors (type of illness and number of prescribed medicines).
Section snippets
Method
A chronic illness sample , comprising asthmatic, cardiac, renal (hemodialysis recipients), and oncology patients, participated in this study. The four illness groups from which patients were sampled were chosen to reflect a variety of disease and treatment characteristics and because there is evidence that low adherence rates are problematic in all four illness groups 29, 30, 31, 32, 33. Patients were included if they had been prescribed one or more medicines for regular use in the
Distribution of beliefs about medicines
The majority of the sample (89%) had strong beliefs in the necessity of their medication for maintaining health (scores greater than scale midpoint). However, over a third (36%) reported strong concerns about the potential adverse effects of using their medication (scores greater than scale midpoint). For 55 patients (17.3% of the sample), necessity scores were lower than concerns scores (negative values for the necessity–concerns differential). There were significant differences in beliefs and
Discussion
This study revealed considerable variation in reported adherence and beliefs about medicines within and between illness groups. A significant proportion of the variance in reported adherence was explained by three factors: the patients' beliefs about their medicines; their type of illness; and their age. A key finding was that medication beliefs were stronger predictors of reported adherence than clinical and sociodemographic factors. When we examined the interaction between medication beliefs
Acknowledgements
This research was supported by a grant from the Department of Health (Pharmacy Enterprise Scheme). The authors acknowledge a number of colleagues who made important contributions to this work. We are grateful to Matthew Hankins (statistician, Division of Psychiatry and Psychology, Kings College, London) for helpful advice on statistical methods. We also thank Railton Scott, Barry Jubraj, Alice Ward, and Linda Dodds for helping with data collection. We are also grateful to Professor Richard
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