A clinico-epidemiologic prevalence survey was conducted in the sub-mountainous area of Northern Bohemia, which is distinguished by the highest proportion of aged people in Bohemian countries. It involved 6057 persons of the 70-79 age group, 1718 persons of the 80-89 age group and 139 persons of the 90+ group, plus control subjects in various other groups. In this study an attempt was made to find an effective measure of the presumed risk factors of pathologic aging in persons of the 70-105 age group. The data were analyzed by the method of coincidence of two parameters of binomial decomposition on the computer Odra. The quantity dependence of the signs was determined, and an index of the compound-risk factor of pathologic aging was calculated. When the numerical value of the index is lower than 56.9 +/- 4.36 for a group of males or 50.3 +/- 3.55 for a group of females, the probability is that a given person in those groups will survive to an advanced age. The total risk is higher for the male sex. Of considerable importance are the genetic burden, external environmental causes, harmful habits, certain "civilization" diseases, and other factors such as disturbed social contacts and defective nutrition.