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Area Based SES & Infant Health . Cindy Chambers, MPH California Department of Health Services Maternal, Child & Adolescent Health/Office of Family Planning Branch Epidemiology and Evaluation Section. Healthy People 2010 Overarching Goals. Goal 1: Increase Quality and Years of Healthy Life
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Area Based SES & Infant Health Cindy Chambers, MPH California Department of Health Services Maternal, Child & Adolescent Health/Office of Family Planning Branch Epidemiology and Evaluation Section
Healthy People 2010 Overarching Goals • Goal 1: Increase Quality and Years of Healthy Life • The first goal of Healthy People 2010 is to help individuals of all ages increase life expectancy and improve their quality of life. • Goal 2: Eliminate Health Disparities • Including differences that occur by gender, race or ethnicity, education or income, disability, geographic location, or sexual orientation.
Background • Problem: • A lack of SES data in MCH datasets limits our ability to monitor the potential effects of economic deprivation on maternal, child and infant health indicators in California. • Solution: • The Harvard Public Health Disparities Geocoding Project Methodology: PH data (i.e. birth data) is geocoded and merged with SES rich census data allowing for rate calculations by census-derived Area-Based Socioeconomic Measures (ABSMs).
Area Based Socioeconomic Measure (ABSM):Percent of Population Below Poverty: Poverty Index • The percent of persons in a given census tract who live at or below the federally defined poverty line • Poverty index broken into four distinct groups • 0-4.9% • 5-9.9% • 10-19.9% • 20-100%
US Census Poverty Thresholds, 2004 Poverty Thresholds for 2004 by Size of Family and Number of Related Children under 18 Source: U.S. Census Bureau, Housing and Household Economic Statistics Division (Last Revised: May 13, 2005)
Area Based Socioeconomic Measure (ABSM):Townsend Index of Deprivation: Townsend Index (UK) • A Composite deprivation measure consisting of a standardized z-score combining data by census tract on: • Percent Crowding • Percent Unemployment • Percent No Car Ownership • Percent Renters • Townsend index is evenly divided into quintiles based on the distribution of our data: • < -2.73 (more affluent) • (-2.73) – (-1.43) • (-1.44) – 0.13 • 0.14 – 2.48 • 2.49 – 16.93 (more deprived)
Study Question To determine the effect of socioeconomic position measured by the ABSMs: • ‘Percent of population below poverty’ (PI) • ‘Townsend Index of Deprivation’ (TI) • on preterm delivery and prenatal care (PNC) utilization in California.
Methods • All methods were adapted from the Harvard School of Public Health’s: ‘Public Health Disparities Geocoding Project’ • Data from the 2000 US Census Bureau were linked by census tract to the 2003 Geocoded California Birth File (N=540,827) • 95% geocoding match rate • 5% un-geocoded were excluded from analyses • 65 California CTs had 0 live births and were excluded from analysis • Area based socio-economic measures (ABSM) were created: • Percent of persons below poverty: 0-4.9%, 5-9.9%, 10-19.9%, 20-100% • Townsend Index of Material Deprivation: evenly divided into quintiles based on the distribution
Methods • Inclusion Criteria: Women 15-44 years • Exclusion Criteria • PNC: Unknown PNC • PTD: Unknown gestational age • Results were analyzed by race/ethnicity and stratified by ABSMs • Rates were calculated per 100 live births • Rate ratios and population attributable fractions (PAF) were calculated
Terms Defined • Rates: Outcomes (Inadequate PNC and PTD) stratified by Poverty Index and Townsend Index and Race/Ethnicity are given per 100 live births. • Kotelchuck index: Calculates the proportion of observed/expected number of PNC visits based on the gestational age of the infant and the month care began grouping them into the following categories: • Inadequate: < 50% of expected visits (or PNC begun after 4th month) • Intermediate: 50-79.9% of expected visits (& PNC begun before 4th month) • Adequate: 80-109.9% of expected visits (& PNC begun before 4th month) • Adequate +: 110% or more expected visits (& PNC begun before 4th month) • Incidence Rate Ratio (IRR): Ratio of two incidence rates. The incidence rate among the exposed proportion of the population, divided by the incidence rate in the unexposed portion of the population, gives a relative measure of the effect of a given exposure. • Population Attributable Fraction (PAF): The theoretical reduction of incidence that would be expected if the entire population had the same level of exposure as a specified referent group (in our case the wealthiest group). * Definitions for IRR and PAF from the Harvard School of Public Health Disparities Geocoding Project
Number of Inadequate PNC and PTD Births by Race/Ethnic Group (N’s), 2003 Note 1: Race/Ethnic N value exclude non geocoded files that could not be assigned an ABSM Note 2: Inadequate PNC N values exclude records with missing PNC data Note 3: Preterm N values exclude missing gestational data as well as records with gestational age out of NCHS limits (17-44 weeks).
Results: Baseline Poverty Data
Percent of Total Population Below Federal Poverty by Race/Ethnicity in California Source: US Census Data, Summary File 3, 2000
Distribution of Live Births byPoverty Index, California 2003 Percent of Population Below Poverty Source: California Birth Certificate Datafile, 2003 and US Census Data, Census 2000 Summary File 3 Note 1: Poverty Measure based on Poverty Status in 1999 by Census Tract in California Note 2: Poverty index is calculated for the 95.2% of births that could be geocoded in California in 2003.
Race/Ethnic Distribution of Live Births by Poverty Index, California 2003 Percent of Population Below Poverty Source: California Birth Certificate Datafile, 2003 and US Census Data, Census 2000 Summary File 3 Note 1: Poverty Measure based on Poverty Status in 1999 by Census Tract in California Note 2: Race/Ethnicity is based on Mother’s Multiple Race Variable in the California Birth Certificate Datafile
Results: Inadequate Prenatal Care
Inadequate Prenatal Care Utilization by Race/Ethnicity, California 2003 Source: California Birth Certificate Master File, 2003
Inadequate Prenatal Care Utilization by Poverty Index, California 2003 Census Tract Poverty PAF: 47.27% Rate of Inadequate Prenatal Care per 100 Live Births Source: California Birth Certificate Datafile, 2003 and US Census Data, Census 2000 Summary File 3 Note 1: Poverty Measure based on Poverty Status in 1999 by Census Tract in California Note 2: Race/Ethnicity is based on Mother’s Multiple Race Variable in the California Birth Certificate Datafile
Inadequate Prenatal Care Utilization byRace/Ethnicity and Poverty Index Census Tracts Stratified by Percent of Population Below Federal Poverty PAF: 35.0% PAF: 49.6% Rate of Inadequate Prenatal Care per 100 Live Births PAF: 23.2% PAF: 43.3% PAF: 30.5% PAF: 25.2% Source: California Birth Certificate Datafile, 2003 and US Census Data, Census 2000 Summary File 3 Note 1: Poverty Measure based on Poverty Status in 1999 by Census Tract in California Note 2: Race/Ethnicity is based on Mother’s Multiple Race Variable in the California Birth Certificate Datafile
Inadequate Prenatal Care Utilization by Townsend Index, California 2003 Townsend Index of Deprivation- Quintiles PAF: 47.39% Rate of Inadequate Prenatal Care per 100 Live Births Source: California Birth Certificate Datafile, 2003 and US Census Data, Census 2000 Summary File 3 Note 1: Poverty Measure based on Poverty Status in 1999 by Census Tract in California Note 2: Race/Ethnicity is based on Mother’s Multiple Race Variable in the California Birth Certificate Datafile
Rates of Inadequate Prenatal Care byRace/Ethnicity and Townsend Index Census Tracts Stratified by Townsend Index of Deprivation Quintiles PAF: 32.7% PAF: 53.4% Rate of Inadequate Prenatal Care per 100 Live Births PAF: 26.7% PAF: 27.0% PAF: 43.5% PAF: 33.7% Source: California Birth Certificate Datafile, 2003 and US Census Data, Census 2000 Summary File 3 Note 1: Townsend Index based on variables in 2003 US Census File Note 2: Race/Ethnicity is based on Mother’s Multiple Race Variable in the California Birth Certificate Datafile
Results: Preterm Delivery
Preterm Delivery by Race/Ethnicity, California 2003 Source: California Birth Certificate Master File, 2003
Preterm Delivery by Poverty Index, California 2003 Census Tract Poverty PAF: 17.5% Rate of Inadequate Prenatal Care per 100 Live Births Source: California Birth Certificate Datafile, 2003 and US Census Data, Census 2000 Summary File 3 Note 1: Poverty Measure based on Poverty Status in 1999 by Census Tract in California Note 2: Race/Ethnicity is based on Mother’s Multiple Race Variable in the California Birth Certificate Datafile
Preterm Delivery byRace/Ethnicity and Poverty Index Census Tracts Stratified by Percent of Population Below Federal Poverty PAF: 10.8% PAF: 19.1% PAF: 16.1% PAF: 14.5% PAF: 5.9% PAF: 8.8% Rate of Inadequate Prenatal Care per 100 Live Births Source: California Birth Certificate Datafile, 2003 and US Census Data, Census 2000 Summary File 3 Note 1: Poverty Measure based on Poverty Status in 1999 by Census Tract in California Note 2: Race/Ethnicity is based on Mother’s Multiple Race Variable in the California Birth Certificate Datafile
Preterm Delivery by Townsend Index, California 2003 Townsend Index of Deprivation- Quintiles PAF: 16.6% Rate of Preterm Delivery per 100 Live Births Source: California Birth Certificate Datafile, 2003 and US Census Data, Census 2000 Summary File 3 Note 1: Poverty Measure based on Poverty Status in 1999 by Census Tract in California Note 2: Race/Ethnicity is based on Mother’s Multiple Race Variable in the California Birth Certificate Datafile
Census Tracts Stratified by Townsend Index of Deprivation Quintiles Rate of Preterm Delivery per 100 Live Births Source: California Birth Certificate Datafile, 2003 and US Census Data, Census 2000 Summary File 3 Note 1: Townsend Index based on variables in 2003 US Census File Note 2: Race/Ethnicity is based on Mother’s Multiple Race Variable in the California Birth Certificate Datafile Note 3: Rate not calculated due to insufficient data (<20 events) Rates of Preterm Delivery byRace/Ethnicity and Townsend Index PAF: 2.1% PAF: 12.4% PAF: 37.8% PAF: 11.7% PAF: 4.8% PAF: 8.0%
Conclusions: Inadequate PNC & PTD • Nearly 50% of all occurrences of inadequate prenatal care utilization (n=18,984) and 17.5% of all preterm births (n=8,046) in California could have been prevented if everyone experienced the risk of those living in the least impoverished census tracts. • For prenatal care, this effect was strongest for Whites and Native Americans (Poverty PAF’s 48.3% and 49.6% respectively) and weakest for Hispanics and African-Americans (Poverty PAF’s 25.3% and 23.2% respectively). • For preterm delivery, this effect was strongest for Native Americans, Pacific Islanders and Hispanics (Poverty PAF’s: 19.1%, 16.1%, 14.5% respectively) and weakest for Asians (Poverty PAF: 5.9%).
Conclusions: Overall • Rates of both inadequate PNC and PTD stratified by CT poverty displayed stepwise gradients from the least to most impoverished populations. • In this analysis the ABSM’s (PI & TI) had a stronger influence our access indicator (inadequate PNC) than our outcome indicator (PTD) (Poverty PAF’s 47.3% vs. 17.5%). • Our findings in California support the Harvard group’s (Krieger et al.) work in two important ways: • The Poverty Index is both easier to compute and yields similar results to other ABSM’s, including the Townsend Index. • The ‘Harvard Geocoding Project’ methodology was successful in identifying large socioeconomic disparities in inadequate prenatal care utilization and preterm delivery in California.
Public Health Implications • Failure to monitor SES disparities masks important variations within and between race/ethnic groups. • In order to move towards achieving HP2010’s goal of eliminating health disparities, data describing SES inequalities must routinely be incorporated into the monitoring and surveillance of maternal, child health indicators. • Surveillance of race/ethnic health disparities can be greatly enhanced by incorporating socioeconomic census variables.
More Information • For More Information on the Methodology used in this study please consult the Harvard School of Pubic Health: “Public Health Disparities Geocoding Project” located at: • http://www.hsph.harvard.edu/thegeocodingproject/