Geographic Disparities of Asthma Prevalence in the Southwestern United States

Asthma is one of the most prevalent chronic diseases in the U.S., and many of its risk factors have so far been investigated and identified; however, evidence is limited on how spatial and geographic disparities impact asthma. The purpose of this study was to provide scientific evidence on the geographic heterogeneity of asthma in the four states of southwestern U.S. (California, Arizona, New Mexico, and Texas) which includes 360 counties. The Behavioral Risk Factor Surveillance System database for these four states covering a period of 2000 to 2011 was used in this analysis, and a Bayesian structured additive regression model was applied to analyze geographic information system. After adjusting individual characteristics, socioeconomic status, and health behaviors, this study has determined that higher odds attributed to location for asthma more likely cluster around the Bay area in California, while lower odds appear in several counties around large cities of Texas, such as Dallas, Houston, and San Antonio. The significance map shows 17 of 360 counties (4.72%) to be high-risk areas for asthma. The level of geographic disparities demonstrates that the county risk of asthma prevalence is about 20.38% (95% confidence interval = 15.64-26.45) higher or lower than the overall asthma prevalence. We provided an efficient method to utilize and interpret existing surveillance data. Within our study area, high-risk areas of asthma were greater in northern California. The visualization may help deliver future interventions on targeted areas and vulnerable populations to reduce geographic disparities in asthma burden.