Burden on the Border: Hot Spot Analyses of Cardiovascular Diseases in Oklahoma and Bordering States

BACKGROUND: During the years 2008-2012, Oklahoma and two of its bordering states, Arkansas and Missouri, ranked in the top ten states for the highest age-adjusted death rates for cardiovascular disease (CVD), while two other bordering states, Colorado and New Mexico, ranked in the bottom ten lowest states (CDC Wonder). Objectives:

1. Determine if there are multi-county areas with statistically significant higher or lower age-adjusted death rates for CVD, heart disease, and/or stroke in Oklahoma and surrounding states; and
2. Determine the extent to which statistically significant hot or cold spots cross state borders. 

METHODS: Using all CVD, heart disease, and stroke age-adjusted death rates by county for Oklahoma and its surrounding six states for the years 2008-2012 from CDC Wonder, we perform Hot Spot analyses. These analyses test for the existence and degree of clustering of high and low disease death rates.

RESULTS:   Results of preliminary analyses show significant (99% confidence level/p value < .01) clustering of high CVD age-adjusted death rates (hot spots) that cover the majority of central and eastern Oklahoma, the majority of Arkansas, the southeastern part of Missouri, and an area along the border of Oklahoma and east Texas. Conversely, we find significant (99% confidence level/p value .01) clustering of low CVD age-adjusted death rates (cold spots) in an area that includes most of Colorado, northern New Mexico, central and north-central Kansas, the San Antonio area, and far west Texas.  Hot and cold spots for heart disease age-adjusted death rates are similar to those for CVD.  A significant (95% confidence level/p value < .05) hot spot for stroke age-adjusted death rates covers the southern and east/northeast parts of Arkansas and across state borders into two Oklahoma counties, the southeastern part of Missouri, and the far eastern part of Texas. An additional significant hot spot is found in the southwestern part of Oklahoma spreading into a few of the bordering counties in Texas. Cold spots for stroke age-adjusted death rates include the San Antonio area, northern New Mexico, and parts of northern and central Colorado.  

CONCLUSIONS: Statistically significant hot spots for CVD and heart disease cross the borders of Oklahoma, Texas, Arkansas, and Missouri. Stroke hot spots cross the borders of Oklahoma, Texas, and Arkansas. This study demonstrates a potential need for coordinated care in counties along the state borders in order to improve health outcomes.