[Determination of stages in the course of chronic diseases].

A schematic conception of staged development of chronic bronchitis and a clinical-mathematical model of the diseases staging have been proposed. The study involved two samples of population: 5204 males aged 40-59 from small towns of the Lithuanian SSR and 1012 residents of the industrial city of Kaunas. It was established that various stages of the disease among which stage II predominated had different incidence rates. Long-term results of the stage-differentiated prophylaxis have furnished evidence for its effectiveness. This principle of stage-distributed therapeutic measures can be adopted for management of other affections.