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