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Abstract

IMPORTANCE: Analysis of geospatial variation in acute bronchitis due to socioeconomic and environmental factors can allow the efficient delivery of resources to populations most at risk.

OBJECTIVE: We sought to determine if small scale variation in socioeconomic factors and emergency room (ER) visits for acute bronchitis are associated in small cities or rural communities. We also modeled the effects of air quality on daily rates of ER visits for acute bronchitis in the context of socioeconomic factors to investigate modifying relationships.

DESIGN, SETTING, AND PARTICIPANTS: We examined ER visits for acute bronchitis in San Luis Obispo and Santa Barbara counties from 2009 through 2012.The study area included 49 ZIP codes with a total population of 765,836 residents.

EXPOSURES: Socioeconomic exposures included ZIP-code level socioeconomic indicators collected for the 2010 American Community Survey. Environmental exposures included PM10, PM2.5, Ozone and temperature.

MAIN OUTCOMES AND MEASURES: The rate of ER visits was calculated for each ZIP code. Spatial clustering (hotspots) of ER visits for acute bronchitis was examined using the local Getis-Ord Gi* statistic. Differences between the distribution of socioeconomic variables across ER visit rate quintiles was assessed using the nonparametric Kruskal-Wallis test. Four Generalized Linear Mixed Models (GLMMs) were used to examine the association between lagged air quality, socioeconomic status and daily rates of emergency room visits for acute bronchitis in each ZIP code.

RESULTS: 5,620 emergency room visits for acute bronchitis were reported during the study period. The four-year rate of ER visits was between 2 and 17 visits per 1,000 residents for all ZIP codes. Two hotspots of ER visits were observed around the communities of Templeton and Lompoc, Ca. Significant differences in home value and rent were observed across ER visit rate quintiles(p = .003 and p < .001, respectively). PM10 was found to be a significant predictor of daily ER visits in a GLMM including only environmental exposures. No exposures were found to be significant in a GLMM with both environmental and socioeconomic exposures. No clear evidence of socioeconomic factors modifying the effect of air quality on ER visits for acute bronchitis was found.

CONCLUSIONS: We found clear evidence of significant variation in ER visit rates for Acute bronchitis at a small geographic scale in rural counties with small to medium size cities. Variation in ER visit rates across ZIP codes was associated with significant differences in socioeconomic factors including home value and rent.

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Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial 3.0 License