Incarceration as a key variable in racial disparities of asthma prevalence

Incarceration has become increasingly frequent in the lives of Americans in the past two decades, with more than 2.3 million individuals behind bars[1] and an additional 8 million under the supervision of parole and probation [2]. Racial and ethnic minorities are disproportionately represented among current and former inmates [3]. For instance, while African-Americans make up 13% of the general US population, they constitute 28% of all arrests and 40% of all people held in prisons and jails, whereas Whites make up 67% of the US population and 70% of all arrests, but only 40% of all people held in state prisons or local jails [3]. Additionally, Black and Latino inmates serve longer sentences for similar crimes compared to their White counterparts.

The disproportionate minority contact with the criminal justice system has implications for individual's health both in prison and after release. Recent studies show that individuals with a history of incarceration are more likely to have asthma, diabetes, and incident hypertension compared to the general population [4–7]. While the specific reasons for increased rates of disease in this population are under investigation, researchers have identified a number of different pathways for why incarceration might augment chronic conditions. To start, prisons and jails are often poorly ventilated, dilapidated, and overcrowded--sites for transmission or exacerbation of respiratory diseases [8, 9]. They offer limited opportunities for cardiovascular disease prevention through healthy diets, regular exercise, or chronic disease education and self-management skills [10, 11]. Moreover, individuals released from prison face legal barriers to employment, housing, public entitlements, and educational opportunities,[12–14] which may exacerbate already limited access to community health care and medical treatment.

For these reasons, we hypothesized that disproportionate rates of incarceration among racial and ethnic minorities may play a role in contributing to racial health disparities in chronic conditions [15–17]. Black and Latino subgroups face persistent health disparities in asthma, diabetes, and hypertension,[18, 19] differentials that parallel those in incarceration, suggesting that perhaps direct exposure to prison, jails, or criminal justice policies may contribute to the increased rates of asthma, diabetes, and hypertension among racial and ethnic minorities. The New York City Health and Nutrition Examination Survey (NYC HANES) provides the unique opportunity to explore incarceration as an contributory factor in racial and ethnic disparities in these health conditions in a community based sample. Using data from the NYC HANES, we examined the impact of having a history of incarceration on the prevalence of asthma, diabetes, and hypertension using both standard regression and propensity score matching techniques; empirically tested whether having a history of incarceration mediates racial and ethnic disparities in these conditions using statistical mediation analysis; and examined access to health care among those with prior incarceration.

In a population-based study of NYC adults, we found that having a history of incarceration is significantly associated with asthma prevalence. Asthma was more common among former inmates than those without this history, and this association persisted after adjustment for age, gender, self-reported race and ethnicity, smoking and illicit drug use, and measures of socioeconomic status using both standard regression and propensity score matching. We also found that asthmatics with a history of incarceration were more likely to have had an asthma attack or been seen in the emergency department in the past year, in spite of similar access to a primary care or health insurance, compared to those never incarcerated. Screening for and treating asthma during incarceration and upon release may be important in reducing asthma morbidity.

The mechanisms by which being incarcerated is associated with asthma are not known. Plausible mechanisms documented in prior studies of non-incarcerated individuals,[30] include higher rates of smoking, drug and alcohol use, domestic violence, or lower socioeconomic status among formerly incarcerated individuals[31–34]. Our data suggest that these mechanisms do not entirely explain the risk for asthma among former inmates. Other possible explanations could include dilapidated prison conditions, indoor allergens (cockroach and mouse droppings)[35], repeated bacterial or viral infections[8], and exposure to contraband and second hand smoke within correctional facilities [31]. Upon release, formerly incarcerated individuals may live in neighborhoods with substandard housing given their difficulties securing employment or public housing[36], heightening their exposure to a variety of environmental asthma triggers. Additionally, former inmates are more likely to be exposed to violence both within prison and in the community, which may increase psychological stress, thus increasing asthma symptoms and decreasing adherence with medications [37]. Finally, studies of formerly incarcerated individuals with tuberculosis and HIV have demonstrated that adherence to medications worsens after release from prison, which may also be a contributor to worse asthma outcomes observed in this study [38]. Additional studies are warranted to investigate the specific mechanisms by which formerly incarcerated individuals may have increased odds for worse asthma outcomes.

Additionally, our results suggest that having a history of incarceration plays a role in augmenting Black-white disparities in asthma prevalence. Two plausible scenarios could explain this finding. First, because Blacks are significantly more likely to be incarcerated, even if the effect of incarceration on health is similar across races, its impact is greater on the aggregate health of Blacks because they are more likely to be incarcerated. Alternatively, exposure to the criminal justice system may be worse for minorities (worse prison housing, longer sentences)[3], thus differentially augmenting the prevalence of asthma among Blacks compared to their White counterparts.

Although exploring the mechanisms whereby incarceration may contribute to racial disparities in asthma is beyond the scope of the present study, our data raise the importance of additional studies exploring how incarceration may contribute to racial health disparities. To this end, local population-based studies might consider enrolling institutionalized adults or at least consider adding questions about past encounters with the criminal justice system, such that this relationship can be further studied longitudinally. Additionally, studies centered on eliminating racial health disparities which censor participants upon incarceration might consider following individuals into correctional facilities where permitted, in order to understand how being incarcerated differentially affects disease management and access to health care among minority populations [39, 40].

Finally, detention in jail or prison, where health care is constitutionally guaranteed, may present a prime opportunity to engage minority populations in disease prevention and treatment and reduce racial disparities. The best known models for bridging health care from correctional facilities to the community involve health care providers and case managers that work both in the correctional facilities and in the community to ensure continuity of care [41, 42]. Although effective in smaller geographic settings, these programs may be difficult to replicate in correctional systems that release prisoners to distant communities. Communities with larger state correctional systems are turning to other programs, which engage individuals immediately prior to or after release from prison using community health workers and utilize the existing structure of the safety net public health system to transition individuals back to community care [43]. Reaching the 2010 Healthy People goal of eliminating health disparities should include an improved understanding of both the role incarceration and the criminal justice system in augmenting racial and ethnic health disparities and its potential as an intervention point for reducing disparities.

There are several limitations in our study. NYC HANES is a cross-sectional study; as such, we are unable to attribute causality. The study also exclusively recruited housed, non-institutionalized NYC residents, selecting for individuals who are less likely to have been incarcerated. As such, we may not have had the power find an association between incarceration and three different chronic medical conditions, thus raising the possibility of type II error as the sample size was limited. Moreover, incarceration was only measured as a single binary question item capturing events that would have included both a brief jail stay after arrest as well as longer periods of imprisonment, thus likely diluting any effect we did detect. Finally, the choice of variables used in the construction of the propensity scores was limited by those measured in NYC HANES. For instance, we did not have measures of neighborhood effects, which have been shown to be related to the prevalence of asthma, diabetes, hypertension [44]. Nonetheless, our propensity score did include variables most likely to be important confounders in the relationship between incarceration and asthma, diabetes, and hypertension--namely measures of race/ethnicity, socioeconomic status, smoking, alcohol use, and illicit drug use.

For this study, we chose to examine the association between having a history of incarceration and three prevalent chronic medical conditions for which there are documented racial and ethnic disparities in NYC--asthma, diabetes, and hypertension. Using data from NYC HANES, one of the few population-based studies on chronic disease which asks participants about incarceration history, we found that having been incarcerated may augment Black-white disparities in asthma among NYC residents. This study demonstrates how including measures of incarceration in epidemiologic studies can improve our understanding of the health of racial and ethnic minorities with asthma. Reaching our national goal of eliminating racial health disparities warrants a better understanding of the role that incarceration and the criminal justice system may play in augmenting these disparities and how prisons and jails might be a suitable place for intervention.