The geographic distribution of diabetes by census tract among insured adults in King County, WA (255.7)

Abstract

Objective: To evaluate the geographic concentration of adult diabetes by census tract (CT) in King County, WA, in relation to socioeconomic factors.Methods: Data for 59767 adult men and women enrolled in the Group Health (GH) healthcare system as of July 31, 2006 were used to estimate the prevalence of diagnosed diabetes at the CT level. Diabetes status was identified using laboratory, pharmacy, and diagnosis data from GH’s electronic medical record databases. Measures of socioeconomic status (SES) drawn from the 2000 US Census were median home values, % of residents with a college degree and median household incomes. Spatial regression models were used to assess the relation between socioeconomic variables and diabetes.Results: Smoothed CT diabetes prevalence, obtained using an Empirical Bayes tool, ranged from 6.9 to 21.2%. The spatial distribution of diabetes was non‐random (Moran’s I=0.46), showing a concentration of high prevalence in south King County and a concentration of low prevalence in north Seattle. In spatial regression models, CT‐level home values and college education were more strongly associated with diabetes than were income. For each additional $100,000 in median home values, diabetes prevalence was 1.4% lower. The three SES factors each explained more of the variance in diabetes than demographic variables. The three SES factors,, population density, race/ethnicity, age and spatial dependence explained 52% of the variance in diabetes, Conclusions: To our knowledge, this is the first report to show major social disparities in adult diabetes prevalence at the CT scale that is based, moreover, on medical diagnosis. Analyses of data at sufficiently fine geographic scale are needed to guide targeted local interventions to prevent and treat chronic disease.Grant Funding Source: Supported by NIH grants P20 RR020774‐03, R01 DK076608‐04 and R21 DK020774