Hippocrates described the importance of patient compliance over 2000 years ago, but the issue continues to generate intense debate [1]. Dictionary definitions often disregard the evolution of language, but definitions in science and medicine are constantly changing. New and modified terminology is needed to capture and communicate emerging ideas, practices and discoveries. The issue of compliance, adherence and concordance is a case in point.
Concordance is not synonymous with either compliance or adherence. Concordance does not refer to a patient's medicine-taking behaviour, but rather the nature of the interaction between clinician and patient. It is based on the notion that consultations between clinicians and patients are a negotiation between equals [2]. How individual patients value the risks and benefits of a particular medicine may differ from the value assigned by their clinicians [3]. In adopting a concordant approach clinicians should respect the rights of patients to decide whether or not to take prescribed medicines. The aim of concordance is the establishment of a therapeutic alliance between the clinician and patient. Concordance is synonymous with patient-centred care. Nonconcordance may occur if a therapeutic partnership is not established and therefore may denote failure of the interaction.
In contrast, compliance and adherence relate to the medicine-taking behaviour of the patient. Compliance and adherence can be estimated using prescription claims records, pharmacy dispensing data, validated survey instruments or electric pill counters, as well as direct measures such as serum drug levels [4]. However, concordance can not. There are still no accepted, valid and reliable tools to measure concordance. While Aronson correctly points to the lack of evidence for improved health outcomes following concordant interactions, research suggests many patients do wish to be involved in decision making about their own treatment regimens [5]. This is particularly true in the field of psychiatry, where many patients may receive only minimal information about their prescribed medicines [6, 7], but may also apply to patients receiving long-term therapy for somatic diseases [8].
Just like Hippocrates, most clinicians recognize the importance of good adherence. In the case of the 81-year-old lady with worsening heart failure, the author attributed non-adherence to the ‘very simple’ cause of morning diuresis. However, understanding the reasons for non-adherence is not always so simple. Patient-related reasons for non-adherence may include forgetfulness, the decision to omit doses, lack of information and emotional factors [4]. Clinician-related reasons may include prescription of complex regimens, failing to explain the benefits and side-effects of treatment, not giving consideration to a patient's lifestyle or the cost of medicines, and having a poor therapeutic relationship with the patient. Most traditional methods of assessing medicine taking do so quantitatively, and provide little insight into the reasons for non-adherence. These methods may lead clinicians to attribute non-adherence to patient-related reasons. Greater use of qualitative research techniques may reveal that the reasons for non-adherence also lie in the way clinicians work and the healthcare system operates. Use of a concordant approach in clinical practice may be one mechanism by which non-adherence can be better understood and addressed.
References
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