Area characteristics and individual-level socioeconomic position indicators in three population-based epidemiologic studies

PURPOSE: There is growing interest in incorporating area indicators into ep idemiologic analyses. Using data from the 1990 U.S. Census linked to indivi dual-level data from three epidemiologic studies, we investigated how diffe rent area indicators are interrelated, how measures for different sized are as compare, and the relation between area and individual level social posit ion indicators. METHODS: The interrelations between 13 area indicators of wealth/income, ed ucation, occupation, and other socioenvironmental characteristics were inve stigated using correlation coefficients and factor analyses. The extent to which block-group measures provide information distinct from census tract m easures was investigated using intraclass correlation coefficients. Logline ar models were used to investigate associations between area and individual -level indicators. RESULTS: Correlations between area measures were generally in the 0.5-0.8 r ange. In factor analyses, six indicators of income/wealth, education, and o ccupation loaded on one factor in most geographic sites. Correlations betwe en block group and census tract measures were high (correlation coefficient s 0.85-0.96). Most of the variability in block-group indicators was between census tracts (intraclass correlation coefficients 0.72-0.92). Although in dividual-level and area indicators were associated, there was evidence of i mportant heterogeneity in area of residence within individual-level income or education categories. The strength of the association between individual and area measures was similar in the three studies and in whites and black s, but blacks were much more likely to live in more disadvantaged areas tha n whites, CONCLUSIONS: Area measures of wealth/income, education, and occupation are moderately to highly correlated. Differences between using census tract or block-group measures in contextual investigations are likely to be relative ly small. Area an! individual-level indicators are far from perfectly corre lated and provide complementary information on living circumstances. Differ ences in the residential environments of blacks and whites may need to be t aken into account in interpreting race differences in epidemiologic studies . (C) 2001 Elseiver Science Inc, All rights reserved.