[Terminological and demographic aspects of comorbidity]

The aim of the present review is to bring into focus the issues regarding terminological and demographic aspects of comorbidity we come across in the modern literature. In this review we gave definitions for the most widely used terms «comorbidity», «polymorbidity», and «multimorbidity». We also considered the historical aspects of their origin and showed the differences between the concepts. The interaction of illnesses can modify the clinical picture and course of illnesses, the nature and severity of complications, reduce the length and quality of life of the patient. The number of comorbid conditions increases significantly with age and contributes to the development of multiple functional disorders leading to polyfunctional failure. In order to choose the most appropriate diagnostic and treatment pattern in elderly and senile patients, it is necessary to take into account all chronic conditions (somatic and mental) accumulated by the patient throughout his life. In order to assess the prevalence and impact on population prognosis and to make health care costs estimation it is more appropriate to use the terms «comorbidity» and «multimorbidity».