Time Trends in Racial and Ethnic Disparities in Asthma Prevalence in the United States From the Behavioral Risk Factor Surveillance System (BRFSS) Study (1999–2011)

摘要

Objectives. We examined whether racial/ethnic disparities in the United States increased over time. Methods. We analyzed data from 3?868?956 adults across the United States from the Behavioral Risk Factor Surveillance System from 1999 to 2011. We used random intercepts models (individuals nested in states) to examine racial/ethnic disparities and time trends in asthma lifetime and its current prevalence, adjusted for covariates. We also investigated the heterogeneity in asthma prevalence by ethnicity of the major zone of residence. Results. Lifetime and current asthma prevalence were higher among non-Hispanic Black populations, with time trends highlighting increasing differences over time (b?=?0.0078; 95% confidence interval [CI]?=?0.0043, 0.0106). Lower odds ratios (ORs) of asthma were noted for Hispanic populations (OR?=?0.74; 95% CI?=?0.73, 0.76). Hispanics in states with more Puerto Rican residents reported greater risks of asthma (OR?=?1.55; 95% CI?=?1.24, 1.93) compared with Hispanics in states with larger numbers of Mexican or other ethnicities. Conclusions. Disparities in asthma prevalence by racial/ethnic groups increased in the last decade, with non-Hispanic Blacks and Puerto Rican Hispanics at greater risk. Interventions targeting asthma treatments need to recognize racial, ethnic, and geographic disparities. Asthma is a major public health issue in the United States that affected nearly 9.4% of the US population in 2009. 1 The burden of asthma morbidity has been borne by both patient households (productive days lost) and the health system (rising health care costs). 1,2 Most population studies on asthma have focused on the role of asthma biology (i.e., predisposition to developing asthma), the hygiene hypothesis (weakened immune defense in countries with higher rates of sanitation problems), and environmental hazards (pollutants both inside and outside the household, including air quality and smoking) in asthma morbidity. However, a small number of studies in the United States and other countries have indicated racial/ethnic and socioeconomic gradients for asthma outcomes among adults and children. 3 Studies have identified racial/ethnic minorities as being at greater risk for morbidity, 4–9 although the direction of these patterns has been disputed by others. 10–13 Studies on racial/ethnic disparities have explained the differences in asthma prevalence through 3 interconnected pathways. First, racial/ethnic differences in income and living standards may explain patterning of exposure to environmental hazards both inside and outside the household. 2,9,14,15 Living conditions within the household (quality of household, dust, and poor pest control) and exposure to air pollution (distance from highways or living in dense areas) may explain racial gradients in asthma to some extent. 2,3,9,11,14–17 Second, racial/ethnic differences in asthma may also be attributed to the patterns of stress (from material deprivation or sociocultural discrimination) that affect immune and allergic responses. 3,18–20 Evidence on this so far has been limited to a couple of critical time windows (pregnancy and postpregnancy), which may have a greater bearing on asthma risks. 20 Third, racial/ethnic disparities in access to regular health care may be another factor, affecting the development, continuation, and worsening of the asthma burden. 10,21,22 Although there is limited understanding of the racial/ethnic disparities in asthma outcomes, a major gap in the current research pertains to the knowledge of time trends in these disparities. Two studies, conducted before 2005, provided some information on changing patterns; both studies examined the changing gradients of hospitalizations and emergency department visits. 6,23 These study authors, Gupta et al. 6 and Ginde et al., 23 found widening Black–White differences in asthma exacerbations that led to hospitalizations. No other studies have examined asthma prevalence differences between racial/ethnic groups and disparities over time. Furthermore, although some researchers have claimed a “protective Hispanic effect,” 24–27 others have highlighted greater morbidity among specific ethnicities. 7,22,28–31 It is less established if this protective effect does exist and whether it extends to all major Hispanic ethnicities. We examined the racial/ethnic gradients and time trends in asthma lifetime and current prevalence in the United States by comparing non-Hispanic White, non-Hispanic Black, and Hispanic populations between 1999 and 2011. In addition, we assessed whether racial/ethnic differences over time persisted after accounting for socioeconomic status (SES) and the heterogeneity in asthma by major Hispanic ethnicities.