Long-term chronic diseases have a high mortality rate around the world, affecting both genders equally. Despite improvements in the diagnosis and treatment of various health problems, lack of treatment compliance remains an obstacle to improving health and patient quality of life, and it carries a high associated socio-healthcare cost. The objectives of this study were to develop the concept of “therapeutic adherence”, which includes both pharmacological compliance as well as non-pharmacological (level of agreement and patient involvement, lifestyle changes, etc.) treatments. The study also aimed to establish the clinical and socio-health impact of non-compliance, the reasons for non-compliance, and methods and strategies to improve compliance. The results of this study support therapeutic adherence as an essential goal of the healthcare system that encompasses all stakeholders involved in patient health.