In a seven-year follow-up of 3,102 Evans County, Georgia, residents examined in the prevalence survey of 1960 through 1962, 143 new cases of coronary heart disease (CHD) occurred, 56 of which resulted in death during the interval. Ethnic differences in CHD among males discovered during 1960 through 1962 were again confirmed. Excess of white males could not be explained by differences in case fatality, diagnostic criteria, missed cases, or by a competing cause of death. In contrast to ethnic differences, differences by social class found in the prevalence survey among white males were not found in the incidence study. Various analyses suggested that the excess prevalence found in the high social class was a reflection of prior high incidence rates in this class. Over time these class differences are disappearing, particularly among younger men.
Cassel J, Heyden S, Bartel AG, Kaplan BH, Tyroler HA, Cornoni JC, Hames CG. Incidence of Coronary Heart Disease by Ethnic Group, Social Class, and Sex. Arch Intern Med. 1971;128(6):901-906. doi:10.1001/archinte.1971.00310240055006