Socioeconomic and racial disparities in invasive pneumococcal disease among children less than five years of age in the post-pneumococcal conjugate vaccine era Open Access

Spicer, Jennifer Oliver (2012)

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This study analyzed the independent effect of census tract-level socioeconomic
characteristics on rates of IPD in children less than five years of age in addition to race-stratified

Socioeconomic and racial trends in IPD incidence in the post-heptavalent
pneumococcal conjugate vaccine (PCV7) era were examined for 905 children less than five years
of age. Data were obtained through active laboratory- and population-based surveillance from the
Centers for Disease Control and Prevention-sponsored Georgia Emerging Infections Program for
the 20-county Metropolitan Atlanta region in Georgia for the time period of 2001 through 2009.
Incidence rates were calculated by race and socioeconomic characteristics using data from the
2000 US Census. Trends in IPD were determined by chi-squared tests for trend, and rate ratios
(RRs) and 95% confidence intervals (CIs) were estimated using Poisson regression.

For 2001 through 2009, the average annual incidence of invasive pneumococcal disease
was 46.1 cases per 100,000 in black children and 28.9 cases per 100,000 in white children
(RR=1.60; 95% CI 1.49, 1.71). Race-stratified incidence rates demonstrated statistically
significant linear trends between IPD rates and some census tract-level socioeconomic factors. In
white children, there were trends of increasing IPD incidence as the percentage of low-income
houses increased (p = 0.007). In black children, trends of increasing IPD incidence were observed
as median household increased (p = 0.005), as census tract poverty decreased (p = 0.009), and as
crowding decreased (p < 0.001). After adjusting for sex and race, only three socioeconomic
measures showed significant associations with IPD incidence in at least one of their strata:
percentage household crowding (RR=0.75; 95% CI 0.59, 0.96), percentage low-income
households (RR=1.38; 95% CI 1.03, 1.84), and census tract median household income (RR=1.34;
95% CI 1.07, 1.69). Race was still a significant predictor of disease even after controlling for sex
and socioeconomic characteristics.

Discussion: The estimated effect of socioeconomic characteristics on IPD rates differs by race.
Although crowding, percentage low-income households, and median household income account
for some health disparities in IPD rates in children, race remains an independent risk factor for
IPD in children in the post-PCV7 era.

Table of Contents

Table of Contents

Background and Literature Review...1


Epidemiology of S, pneumoniae...1

Racial Disparities in Invasive Pneumococcal Disease...3

Socioeconomic Health Disparities...4

Geocoding and Area-based Socioeconomic Measures...4

Socioeconomic Measures and S. pneumoniae Infection...6

Thesis Rationale and Objective...7


Study Population...9

Geocoding and US Census Data...10

Socioeconomic Variables...10

Case Variables...11

Statistical Analysis...13



Strengths and Limitations...22

Public Health Implications and Future Directions...23




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