title: Improving population representation through geographic health information systems: mapping the MURDOCK study.
abstract: This paper highlights methods for using geospatial analysis to assess, enhance, and improve recruitment efforts to ensure representativeness in study populations. We apply these methods to the Measurement to Understand Reclassification of Disease of Cabarrus/Kannapolis (MURDOCK) study, a longitudinal population health study focused on the city of Kannapolis and Cabarrus County, NC. Although efforts have been made to recruit a participant registry that is representative of the 18 ZIP code catchment region inclusive of Cabarrus County and Kannapolis, bias in such recruitment is inevitable. Participants in the MURDOCK study are geospatially referenced at entry, providing information that can be used to monitor and guide recruitment efforts. MURDOCK participant population representativeness was assessed using chi-squared tests to compare the MURDOCK population with 2010 Census data, relative to both the entire 18 ZIP code catchment area and for individual Census tracts. A logistic regression model was fit to characterize Census tracts with low recruitment, defined by fewer than 56 participants from that tract. The distance to the site at which participants enrolled was calculated, and median distance to enrollment site was used in the logistic regression. Tracts with low recruitment rates contained higher minority and younger populations, suggesting specific strategies for improving recruitment in these areas. Areal units farther away from enrollment sites were also not well-sampled, despite being in the specified study area, indicating that distance traveled to enrollment may be a barrier. These results have implications for targeting recruitment efforts and representative samples more generally, including in other population-based studies.
authors: National Center for Geospatial Medicine, School of Natural Resources and Environment, University of Michigan Ann Arbor, MI, USA.
authors: Ben W
authors: BW
authors: Strauss
authors: National Center for Geospatial Medicine, School of Natural Resources and Environment, University of Michigan Ann Arbor, MI, USA.
authors: Ellis M
authors: EM
authors: Valentiner
authors: Duke Translational Research Institute, Duke University Durham, NC, USA ; Duke Global Health Institute, Duke University Medical Center Durham, NC, USA.
authors: Sayanti
authors: S
authors: Bhattacharya
authors: Duke Translational Research Institute, Duke University Durham, NC, USA.
authors: Michelle M
authors: MM
authors: Smerek
authors: Duke Translational Research Institute, Duke University Durham, NC, USA.
authors: Ashley A
authors: AA
authors: Dunham
authors: Division of Cardiovascular Medicine, Duke University Medical Center Durham, NC, USA ; Duke Clinical Research Institute, Duke University Medical Center Durham, NC, USA.
authors: L Kristin
authors: LK
authors: Newby
authors: National Center for Geospatial Medicine, School of Natural Resources and Environment, University of Michigan Ann Arbor, MI, USA ; Department of Pediatrics, University of Michigan Ann Arbor, MI, USA ; Department of Obstetrics and Gynecology, University of Michigan Ann Arbor, MI, USA.
authors: Marie Lynn
authors: ML
authors: Miranda
keywords: Geographic health information systems (GHIS); neighborhood; population-based studies; sample recruitment; spatial analysis