Background: This study examined the extent to which areal socio-economic gradients in all-cause and cardiovascular disease (CVD) mortality among US men and women aged 25-64 years increased between 1969 and 1998.
Methods: Using factor analysis 17 census tract variables were used to develop an areal index of socio-economic status that was used to stratify all US counties into five socio-economic categories. By linking the index to county-level mortality data from 1969 to 1998, we calculated annual age-adjusted mortality rates for each area socio-economic group. Poisson regression models were fitted to estimate areal socio-economic gradients in mortality over time.
Results: Areal socio-economic gradients in all-cause and cardiovascular mortality have increased substantially over the past three decades. Compared to men in the highest area socio-economic group, rates of all-cause and CVD mortality among men in the lowest area socio-economic group were 42% and 30% greater in 1969-1970 and 73% and 79% greater in 1997-1998, respectively. The gradients in mortality among women were steeper for CVD than for all causes. Compared to women in the highest area socio-economic group, rates of all-cause and CVD mortality among women in the lowest area socio-economic group were 29% and 49% greater in 1969-1970 and 53% and 94% greater in 1997-1998, respectively.
Conclusions: Although US all-cause and cardiovascular mortality declined for all area socio-economic groups during 1969-1998, the gradient increased because of significantly larger mortality declines in the higher socio-economic groups. Increasing areal inequalities in mortality shown here may be related to increasing temporal differences in the material and social living conditions between areas.