Young adult mortality as an index: associations with income and social indicators.

In an effort to find an indicator for use in studies of the epidemiological impact of drug abuse in California in the late 1960s, we recognized that, for comparative analyses, cause specific mortality was less attractive than total mortality of the population group principally affected, young adults. This paper examines the all cause mortality; and its major components for young adults, age 15-24, (Young Adult Mortality, YAM) for the U.S. as it varied over time and for various countries in relation with income and social indicators. Between 1961 and 1969 in the United States a striking overall increase occurred (40.6%) with motor vehicle accidents a dominant cause which neither accounted for, all the increase, nor for the racial gradients. Male rates are higher than female rates. In the U.K. a steep and persistent social class gradient has been shown. Comparative studies done among countries whose vital statistics are reported to the World Health Organization, were analyzed in relation to international social and economic indicators. Countries with a Per Capita Income (GNP/person) below $3,000 show a striking increase in mortality from diseases with decreasing income, but above $3000 GNP/person "environmental" (non-disease) causes of death begin to increase, so that total mortality increases with increasing income. Two distinct groups of "industrialized countries" can be identified, seven with low mortality, and ten with high mortality. Per capita expenditure on education and ethnic homogeneity appear to be the social indicators which best discriminate between these two groups of countries.