DISCUSSION
We conducted a cross-sectional analysis of data from a large pediatric
SCD Center in the Southeastern U.S. to quantify the contributions of
neighborhood socioeconomic deprivation and racial composition to ACS
recurrence. Our results show that children with SCD residing in
socioeconomically deprived neighborhoods have fewer occurrences of ACS,
and this association is accounted for by the predominantly African
American make-up of the community. This is the first report documenting
a relationship between community characteristics and risk of ACS
recurrence in pediatric SCD population in the United States.
Area deprivation is a well-documented risk factor for chronic diseases
and their exacerbations in adult22-24 and pediatric
populations.25 However, research has been conducted in
predominantly White or racially mixed populations. In contrast, our
sample comprises exclusively African American children with SCD living
in the state of Alabama. In our study, neighborhood socioeconomic
deprivation was associated with less recurrent ACS, and this effect was
explained by the racial composition of the community. It is possible
that the area deprivation index used in this analysis, which has been
developed for the general population, does not work well when applied to
a racially homogeneous African American sample.14,15Race-specific area-level measures may be needed for accurate assessment
of the role of socioeconomic environment in child health.
Our results show that residence in a predominantly African American
neighborhood substantially reduces the risk of ACS recurrence. A number
of previous studies have reported a positive health effect of residence
in racially or ethnically homogenous areas, or the so-called “ethnic
density effect.”26,27 The health benefits of ethnic
density have been attributed to the buffering effect of neighborhood
cohesion, enhanced social support, and a stronger sense of
community.27-29 Ethnic density may provide
opportunities to engage with others who share similar cultural or ethnic
background, and these supportive interactions may confer social
advantages that facilitate recovery from life
stressors.30 These effects are further strengthened
after controlling for area deprivation.31 For example,
previous research has documented that neighborhood cohesion offsets the
adverse health effects of neighborhood socioeconomic disadvantage,
likely through minimizing stress related to living in mixed
neighborhood.32 This interpretation is plausible in
the context of SCD, as stress is a known risk factor for systemic
inflammation, which is associated with worse SCD outcomes, including
recurrent ACS.33,34 Family stress may negatively
affects offspring which was suggested by reports associating parental
stress with life quality scores in children with
SCD.35
Environmental exposures, whether indoor or outdoor, have been shown to
affect SCD outcomes. A recent study from the Southern United States
showed that higher levels of ambient carbon monoxide are associated with
increased ED visits for SCD, with particularly strong effects among
children.36 Epidemiologic studies in Europe reported
that high levels of ozone, nitric oxide, and wind speed; and low levels
of carbon monoxide and nitrous oxide are associated with increased ED
admissions for SCD crises, including ACS.10,37 These
environmental factors may have contributed to the risk of ACS recurrence
in our cohort.
Previous studies have linked ACS risk with public
insurance38 and rural residence.39Such associations were not observed in our data. Access to care,
measured by distance to the hospital and by the severity of the ACS
episode, was also not associated with ACS recurrence in our sample. Our
study corroborates previous reports of increased ACS in SCD patients
with asthma40,41 and SS phenotype.8As well, ACS in our sample was more prevalent in males, confirming a
reported association between male sex and increased risk of
ACS.42,43
Despite an increased scientific interest in the role of
socio-environmental factors for SCD outcomes, medical records rarely
include sufficient patient-level socioeconomic data. This study
demonstrates that area-level measures can be used as a proxy of
patient-level socioeconomic data. It also highlights the opportunity for
expanding health records with publicly available area-level information
that is relevant for clinical decision-making. Small-area measures can
be a clinically useful tool for identifying high-risk SCD patients who
may benefit from ACS prevention approaches.
The current study has several limitations. Our data does not include
individual-level socioeconomic characteristics such as household income
and parent education. Therefore, we cannot determine if the observed
neighborhood effects vary by individual-level socioeconomic position. We
also do not have measures of environmental exposures related to their
residence that can affect their lung health. The reported associations
may not be applicable to adult SCD populations or patients living in
different regions. Finally, the cross-sectional design, with its
inherent information bias and inability to control for all confounders,
prevents us from making causal inferences about the observed
relationships between neighborhood socioeconomic deprivation, racial
composition, and ACS.
Our results indicate that children with SCD living in socioeconomically
deprived neighborhoods have lower risk of recurrent ACS due to the
protective effect of African American neighborhood composition. These
results provide initial evidence for the role of neighborhood
environment for ACS risk in pediatric patients with SCD. Future research
should investigate these associations in a SCD sample from multiple U.S.
regions. Neighborhood characteristics and area-level exposures may also
be incorporated in ACS risk prediction models.
Our study sheds light on the role of community characteristics for SCD
outcomes and highlights the potential role of neighborhood cohesion and
social support in reducing ACS recurrence. However, these
health-conferring characteristics must be interpreted in the
socio-political context that reproduces concentrated socioeconomic
disadvantage in areas of high racial density. Addressing the inequitable
distribution of socioeconomic resources by race is critical for
improving health and reducing inequalities. Futures studies in this
population should attempt to collect prospective individual-level data
in order to examine more precisely the effects of racial composition and
socioeconomic deprivation on SCD complications.
Conflict of Interest Statement: The authors have no conflicts
of interest relevant to this article to disclose
Financial Disclosure Statement: The authors have no financial
relationships relevant to this article to disclose
Funding Source: None