Social Deprivation Index (SDI)

Background

Addressing social determinants of health (SDOH) is critical to achieving the Triple Aim of lower costs, improved care, and better population health. It is unclear which social determinants of health best direct clinical and community health interventions and guide adjustments to quality measures and payments. We developed a Social Deprivation Index (SDI) to quantify levels of disadvantage across small areas, evaluate their associations with health outcomes, and address health inequities. This measure of social deprivation, in combination with other indicators, has potential application in identifying areas that need additional health care resources.

The Social Deprivation Index measures was initially developed by Butler et al. (2012) using 2005–2009 American Community Survey (ACS) 5-year estimates (http://www.census.gov/acs/www/) and calculated at the Primary Care Service Areas (PCSA).  This measure was updated 1) with more recent ACS data (5-year estimates from 2008-2012 and from 2011-2015) and 2) using additional areas: counties, census tract, Zip Code Tabulation Areas (ZCTA), and PCSAs.

SDI Defined

SDI is a composite measure of area level deprivation based on seven demographic characteristics collected in the American Community Survey (https://www.census.gov/programs-surveys/acs/) and used to quantify the socio-economic variation in health outcomes.

Methodology

The SDI is a composite measure of seven demographic characteristics collected in the American Community Survey (ACS): percent living in poverty, percent with less than 12 years of education, percent single parent household, percent living in rented housing unit, percent living in overcrowded housing unit, percent of households without a car, and percent non-employed adults under 65 years of age.

The SDI measure was calculated at four geographic areas: county, census tract, aggregated Zip Code Tabulation Area (ZCTA), and Primary Care Service Area (PSCA, v 3.1).

  • Counties are an administrative division of a state offering certain local governmental services.
  • Census tracts are semi-permanent county subdivisions.
  • ZCTAs are generalized U.S. Postal Service Zip Codes.
  • PCSAs are small areas of aggregated census tracts and were created by Dartmouth University for the Health Resources and Service Administration. PCSAs represent travel patterns of Medicare patients to primary care services. To construct the PCSA-level SDI, all the ACS population measures were first extracted at the census tract level and then, summarized at the PCSA level.

The SDI measures for the county, census tract, and ZCTA levels were developed directly from ACS population measures.

Based on similar international and national indices, we started with a larger list of 14 candidate measures available in the ACS.  We converted each of these measures into centiles to create a common scale for easy interpretation of results.

We used factor analysis methods to create the Social Deprivation Index. Factor analysis is a statistical technique used to investigate the relationship between a group of observed variables and an unobserved (or “latent”) variable underlying a concept. It allows exploration of the association among measures through reducing a large number of related variables into the underlying latent factors.

The output from the factor analysis model is a factor loading for each variable. The factor loading represents the strength of correlation between the variables that comprise the factor and the factor itself. The factor loadings can be interpreted as though they are regression coefficients; the higher the factor loading score, the greater the variation that is explained by that variable.

To simplify the model, we restricted it to only include measures with factor loadings greater than 0.60, thus excluding percent black and percent in high-needs age groups.

We constructed a final SDI measure based on weighted factor loading scores for each measure. We examined the difference between models that included either non-employed (those not seeking work) or unemployed (those actively seeking work). The factor loading for the model using non-employed was slightly higher than for the model using unemployed. These initial results were reproduced for each period and for each geography.

Table 1. List of Domains and Variables used in creating Social Deprivation Index
Table 1. List of Domains and Variables used in creating Social Deprivation Index:

Domain

Variable

Table 1. List of Domains and Variables used in creating Social Deprivation Index:

Income

Percent population less than 100% FPL
Table 1. List of Domains and Variables used in creating Social Deprivation Index:

Education

Percent population 25 years or more with less than 12 years of education
Table 1. List of Domains and Variables used in creating Social Deprivation Index:

Employment

Percent non-employed
Table 1. List of Domains and Variables used in creating Social Deprivation Index: HousingPercent population living in renter occupied and crowded housing units
Table 1. List of Domains and Variables used in creating Social Deprivation Index:

 

Percent population living in crowded housing units
Table 1. List of Domains and Variables used in creating Social Deprivation Index:

Household Characteristics

Percent single-parent households with dependents < 18 years
Table 1. List of Domains and Variables used in creating Social Deprivation Index:

Transportation

Percent population with no car

Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2008-2012 5-year Summary File American Community Survey (ACS)
Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2008-2012 5-year Summary File American Community Survey (ACS):

Description

Sequence No

Table ID

Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2008-2012 5-year Summary File American Community Survey (ACS):

State FIPS code

  
Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2008-2012 5-year Summary File American Community Survey (ACS):

County FIPS code

  
Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2008-2012 5-year Summary File American Community Survey (ACS):

Census Tract FIPS code

  
Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2008-2012 5-year Summary File American Community Survey (ACS):

ZCTA5 FIPS code

  
Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2008-2012 5-year Summary File American Community Survey (ACS):

Population -estimate

sf0002

B01001

Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2008-2012 5-year Summary File American Community Survey (ACS):

Percent Single parent households (Single Parent households with children under 18)

sf0036

B11003

Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2008-2012 5-year Summary File American Community Survey (ACS):

Percent drop-out (Persons with no high school diploma estimate)

sf0043

B15003

Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2008-2012 5-year Summary File American Community Survey (ACS):

Percent below poverty estimate (Income in the past 12 months below poverty level)

sf0047

B17001

Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2008-2012 5-year Summary File American Community Survey (ACS):

Percent Non-employed (Persons Civilian Percent non-employed estimate )

sf0075

B23001

Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2008-2012 5-year Summary File American Community Survey (ACS):

Percent Renter Occupied (Tenure Housing)

sf0102

B25003

Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2008-2012 5-year Summary File American Community Survey (ACS):

Percent Crowded (Tenure by Occupants Per Room greater than 1.01 to 1.50 occupants per room)

sf0102

B25014

Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2008-2012 5-year Summary File American Community Survey (ACS):

Percent No Car (Tenure by Vehicles Available - No Vehicle available)

sf0104

B25044


Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2011-2015 5-year Summary File American Community Survey (ACS)
Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2011-2015 5-year Summary File American Community Survey (ACS): DescriptionSequence NoTable ID
Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2011-2015 5-year Summary File American Community Survey (ACS): State FIPS code  
Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2011-2015 5-year Summary File American Community Survey (ACS): Countyl FIPS code  
Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2011-2015 5-year Summary File American Community Survey (ACS): Census Tract FIPS code  
Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2011-2015 5-year Summary File American Community Survey (ACS): ZCTA5 FIPS code  
Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2011-2015 5-year Summary File American Community Survey (ACS): Population -estimatesf0002B01001
Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2011-2015 5-year Summary File American Community Survey (ACS): Percent Single parent household with children under 18 estimatesf0036B11003
Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2011-2015 5-year Summary File American Community Survey (ACS): Percent drop-out (Persons with no high school diploma estimate)sf0043B15003
Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2011-2015 5-year Summary File American Community Survey (ACS): Percent below poverty estimate (Income in the past 12 months below poverty level)sf0048B17001
Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2011-2015 5-year Summary File American Community Survey (ACS): Percent Non-employed (Persons Civilian Percent non-employed estimate )sf0076B23001
Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2011-2015 5-year Summary File American Community Survey (ACS): Percent Renter Occupied (Tenure Housing)sf0103B25003
Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2011-2015 5-year Summary File American Community Survey (ACS): Percent Crowded (Tenure by Occupants Per Room -1.01 to 1.50 occupants per room)sf0103B25014
Table 2. Social Deprivation Index List of Variables with corresponding Sequence Number and Table ID from the 2011-2015 5-year Summary File American Community Survey (ACS): Percent No Car (Tenure by Vehicles Available - No Vehicle available)sf0105B25044

Table 3. Factor Loadings of Social Deprivation Index Items (2008-2012 ACS 5-yr Summary File)
Table 3. Factor Loadings of Social Deprivation Index Items (2008-2012 ACS 5-yr Summary File) : GeographyPCSA level ZCTA Census Tract County
Table 3. Factor Loadings of Social Deprivation Index Items (2008-2012 ACS 5-yr Summary File) :  Reduced Reduced Reduced Reduced
Table 3. Factor Loadings of Social Deprivation Index Items (2008-2012 ACS 5-yr Summary File) : <12 Years Schooling0.801 0.800 0.754 0.781
Table 3. Factor Loadings of Social Deprivation Index Items (2008-2012 ACS 5-yr Summary File) : Crowding0.641 0.673 0.591 0.631
Table 3. Factor Loadings of Social Deprivation Index Items (2008-2012 ACS 5-yr Summary File) : No Car0.731 0.729 0.696 0.621
Table 3. Factor Loadings of Social Deprivation Index Items (2008-2012 ACS 5-yr Summary File) : Nonemployed0.678 0.667 0.589 0.444
Table 3. Factor Loadings of Social Deprivation Index Items (2008-2012 ACS 5-yr Summary File) : Poverty0.856 0.874 0.854 0.851
Table 3. Factor Loadings of Social Deprivation Index Items (2008-2012 ACS 5-yr Summary File) : Renter Occupied0.744 0.741 0.740 0.530
Table 3. Factor Loadings of Social Deprivation Index Items (2008-2012 ACS 5-yr Summary File) : Single Parent Family0.841 0.830 0.766 0.808

Table 3. Factor Loadings of Social Deprivation Items (2011-2015 ACS 5-yr Summary File)
Table 3. Factor Loadings of Social Deprivation Items (2011-2015 ACS 5-yr Summary File) : GeographyPCSA level ZCTA Census tract County
Table 3. Factor Loadings of Social Deprivation Items (2011-2015 ACS 5-yr Summary File) :  Reduced Reduced Reduced Reduced
Table 3. Factor Loadings of Social Deprivation Items (2011-2015 ACS 5-yr Summary File) : <12 Years Schooling0.808 0.798 0.754 0.757
Table 3. Factor Loadings of Social Deprivation Items (2011-2015 ACS 5-yr Summary File) : Crowding0.633 0.653 0.590 0.600
Table 3. Factor Loadings of Social Deprivation Items (2011-2015 ACS 5-yr Summary File) : No Car0.696 0.720 0.689 0.600
Table 3. Factor Loadings of Social Deprivation Items (2011-2015 ACS 5-yr Summary File) : Nonemployed0.702 0.677 0.593 0.644
Table 3. Factor Loadings of Social Deprivation Items (2011-2015 ACS 5-yr Summary File) : Poverty0.865 0.881 0.864 0.805
Table 3. Factor Loadings of Social Deprivation Items (2011-2015 ACS 5-yr Summary File) : Renter Occupied0.718 0.738 0.742 0.725
Table 3. Factor Loadings of Social Deprivation Items (2011-2015 ACS 5-yr Summary File) : Single Parent Family0.845 0.834 0.777 0.832

Available Files

References

  1. Butler DC, Petterson S, Phillips RL, Bazemore AW. Measures of Social Deprivation That Predict Health Care Access and Need within a Rational Area of Primary Care Service Delivery. Health Services Research. 2013;48(2 Pt 1):539-559. doi:10.1111/j.1475-6773.2012.01449. https://www.ncbi.nlm.nih.gov/pubmed/22816561(www.ncbi.nlm.nih.gov)
  2. Philips RL, Liaw W, Crampton P. How Other Countries are Using Deprivation Indices. Health Affairs, 2016: 35 (11):1991-1998 http://content.healthaffairs.org/content/35/11/1991.abstract(content.healthaffairs.org)
  3. Liaw W. Krist AH, Tong ST, Sabo R. et al. Living in “Cold Spot” Communities Is Associated with Poor Health and Health Quality. J Am Board Fam Med. 2018; 31:342-350