The definitions of the patient co-operation are not uniformed. This causes many difficulties when comparing the results of the studies. I searched the net and I found some good summaries about the meaning of adherence, compliance, concordance, persistence etc.
As follows adherence, compliance, persistence are defined based on the classifications of WHO, NICE, ISPOR and ABC.
Adherence: 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.
Adherence: ‘the extent to which the patient’s behaviour matches agreed recommendations from the prescriber’. Adherence emphasises the need for agreement and that the patient is free to decide whether or not to adhere to the prescriber’s recommendation.
Concordance: this is a recent term whose meaning has changed. It was initially applied to the consultation process in which prescriber and patient agree therapeutic decisions that incorporate their respective views, but now includes patient support in medicine-taking as well as prescribing communication. Concordance reflects social values but does not address medicine-taking and may not lead to improved adherence.
Persistence: The length of time from initiation to discontinuation of therapy.
Medication compliance (synonym: adherence): refers to the degree or extent of conformity to the recommendations about day-to-day treatment by the provider with respect to the timing, dosage, and frequency. It may be defined as “the extent to which a patient acts in accordance with the prescribed interval, and dose of a dosing regimen.”
Medication persistence: refers to the act of continuing the treatment for the prescribed duration. It may be defined as “the duration of time from initiation to discontinuation of therapy.” Persistence analyses must include a prespecified limit on the number of days allowed between refills, considered the “permissible gap.”
Medication adherence: is the process by which patients take their medication as prescribed. It consists of three parts:
Initiation: occurs when the patient takes the first dose of the prescribed medication.
Discontinuation: occurs when the patient stops taking the prescribed medication.
Execution: patients’ accuracy in following the day-to-day dosing regimen while still actively taking the medication. It is the multidimensional outcome of the comparison of two time series: the prescribed drug dosing regimen and the patient’s drug dosing history while he or she is still engaged with treatment. Evaluation is disease/treatment specific.
Persistence: the length of time that the patient continues to be engaged with the prescribed dosing regimen.
Medication adherence is best quantified using two parameters: execution and persistence.
Medication therapy management: The overall process of assisting patients in the initiation and conduct of their drug therapies.
Adherence-Related Behavioral Science: the many disciplines concerned with patients’ and providers’ decision-making, acceptance of, and ability to effectively adhere to a medication regimen.
Pharmionics: The discipline concerned with the quantitative assessment of what patients do with prescribed medicines. It is concerned with the study of how prescribed medications are used by ambulatory patients. Pharmionics (ion=to go) means “the going of the pharmaceutical(s)” and constitutes thus a link to the biomedical field as a natural input to pharmacokinetic and pharmacodynamic models for quantitative analysis of pharmacometric and economic consequences of dosing errors.