What's in a name? Compliance, adherence and concordance in chronic psychiatric disorders.

About half or more of the patients with chronic psychiatric illnesses, either do not take their medications correctly, or completely stop taking them. The problem of poor initial compliance or adherence is often compounded by a continued decline in compliance/adherence over time. The failure to take medicines, adversely affects the outcome of treatment, and places a huge burden of wasted resources on the society. Three terms have been used to describe medication-taking among patients with chronic psychiatric disorders. Compliance is defined as "the extent to which the patient's behaviour matches the prescriber's recommendations". Though compliance has been frequently employed to describe medication-taking behaviour, it has proved problematic because it refers to a process where the clinician decides on a suitable treatment, which the patient is expected to comply with unquestioningly. Studies over the past few decades have emphasized the importance of patients' perspectives in medication-taking, based on their own beliefs, their personal circumstances, the information and resources available for them. Adherence has been used as a replacement for compliance in an effort to place the clinician-patient relationship in its proper perspective. Adherence refers to a process, in which the appropriate treatment is decided after a proper discussion with the patient. It also implies that the patient is under no compulsion to accept a particular treatment, and is not to be held solely responsible for the occurrence of non-adherence. Adherence has been defined as "the extent to which a person's behaviour, taking medication, following a diet, and/or executing lifestyle changes, corresponds with agreed recommendations from a health care provider". To overcome certain problems in the concept of adherence, a third term concordance has been used. The concept of concordance has evolved from a narrower view, emphasizing an agreement between the clinician and the patient, which takes into account each other's perspective on medication-taking, to a broader process consisting of open discussions with the patient regarding medication-taking, imparting information and supporting patients on long-term medication. It is a process, which entertains patients' views on medication-taking, and acknowledges that patients' views have to be respected even if they make choices, which appear to be in conflict with the clinician's views. Although none of these terms are ideal solutions to understanding the complex process of medication-taking behaviour of patients, the move from compliance to adherence and concordance represents genuine progress in this field, which puts the patient's perceptions at the centre of the whole process.