Non-adherence to medication is a serious problem. If a patient does not take medication regularly, the therapeutic effect expected, based on large clinical studies, may not be achieved. Only about 50% of patients with chronic conditions follow the recommendations. Due to the magnitude of this phenomenon, the non-adherence of many patients, in addition to the impact on their health, also has serious social and economic consequences. The term 'adherence to recommendations' (compliance) usually assumes a passive participation of the treated person, consisting only of compliance with the recommendations of the treating physician, which, as practice shows, especially in long-term treatment, often fails. The patient must also be an active party in this process and the treatment strategy should be the result of his/her agreement with the doctor (concordance). Therefore, the preferred term is "sticking to the therapeutic plan". (adherence). The patient's understanding of the meaning of diagnostic and therapeutic measures promotes their acceptance and fundamentally improves the effectiveness of treatment. Only a conscious, partnership cooperation of both parties can lead to a fundamental change in the attitude of the patient, and often also of those around him or her - from passive (waiting for the disease with the hope that it will not appear) to active (conscious actions aimed at controlling the state of health and preventing possible diseases). In practice, regardless of the original intention and the very meaning of the words, the terms compliance, concordance and adherence are often used interchangeably.
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