TABLE 2.

Definitions Used to Calculate Dichotomous Contrasts for the Association Between Each Social Factor and Adult All-Cause Mortality and Prevalence Estimates for Each Social Factor: United States, 2000

	Definition for RR Estimates From Studies	Prevalence Estimates Used in PAF Calculationsa
Social Factor		Definition	Source
Low education	< high school vs ≥ high school diploma or equivalent	% of adult population with < high school education	US Census Bureau Summary File 375
Poverty	Annual household income of < $10 000 vs ≥ $10 000b	% of adult population living below the poverty level	US Census Bureau Summary File 375
Low social support	“Low” vs “high” score on a social network indexc	% of adult population with score of 0 or 1 on social network indexc	National Health and Nutrition Examination Survey III76
Area-level poverty	≥ 20% of population living below poverty level vs < 20% living below poverty leveld	% of adult population living in counties with ≥ 20% of population living below the poverty level	US Census Bureau Summary File 375
Income inequality	Gini coefficient 1 SD above the mean vs the mean value	% of adult population living in counties with Gini coefficient at or above the 25th percentilee	US Census Bureau, derived from household income data75
Racial segregation	% Black 1 SD above the mean vs the mean value	% of adult population living in counties with ≥ 25% of population reporting their race/ethnicity as non-Hispanic Black	US Census Bureau Summary File 177

Note. PAF = population attributable fraction; RR = relative risk.

^aAdult population was defined as those aged ≥ 25 years.

^b$10 000 roughly corresponded to the poverty threshold for a family of 4 in the early to mid-1980s,⁷⁸ when many of the included studies were conducted.

^cSocial network indices in most included studies were based on that developed by Berkman and Syme⁷⁹; low scores indicated few social ties. The social network index included in NHANES III, from which the prevalence estimate was derived, ranged from 0 to 4, and included indicators of marriage or partnership, contact with friends and relatives, frequency of church or religious service attendance, and participation in voluntary organizations.⁷⁶

^d20% or more of population living below the poverty level corresponds to the criteria for a “poverty area” put forth by the US Census Bureau.⁸⁰

^eA Gini coefficient in the top 25th percentile (0.459) represents areas with the highest levels of income inequality in the United States.