Changing patterns of ischaemic heart disease mortality in New Jersey 1968-1982, and the relationship with urbanization.

Geographical variations in the declining rates of ischaemic heart disease (IHD) mortality may provide clues about various environmental risk factors responsible as a mass influence on the population IHD rate. The rate of IHD decline in 18 of 21 NJ counties was 2 to 45% less than the USA national rate of decline. The overall decline of IHD mortality in New Jersey (NJ) counties lagged significantly (p less than 0.05 to p less than 0.0003) behind the national trend. Age-adjusted mortality rate (AAMR) for IHD in NJ's 21 counties were 4% to 56% higher than the US rates. The IHD mortality rate of 14 of 21 NJ, counties and the entire state were significantly (p less than 0.005 to p less than 0.000001) above the US rate. Highly urbanized, industrialized, and densely populated NJ counties had the highest IHD rates. In these highly urbanized, industrialized and overcrowded NJ counties the AAMR for IHD was significantly higher and the IHD decline was significantly lower than that in the US. There was a significant (p less than 0.02 to p less than 0.00001) inverse association between annual per capita income and IHD rates. These data suggest that a high degree of urbanization, extensive industrialization, high population density and low socioeconomic status were acting as mass influences on the NJ population IHD rate.