University of Wisconsin–Madison Medical College of Wisconsin

Same People, Different Results: Categorizing Cancer Registry Cases Across the Rural-Urban Continuum

Andrea M. Schiefelbein, MSPH; John K. Krebsbach, BS; Amy K. Taylor, MD; Chloe E. Haimson, PhD; Patrick R. Varley, MD; Melissa C. Skala, PhD; John M. Eason, PhD; Noelle K. LoConte, MD

WMJ. 2024;123(2):78-87

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Background: Many rural-urban indexes are utilized in cancer research. This variation introduces inconsistencies between studies. Recommendations on index use have prioritized geographical unit over feasibility of inclusion in analysis. We evaluated rural-urban indexes and recommend one for use to increase comparability across studies.

Methods: We assessed 9 US rural-urban indexes regarding their respective rural and urban code ranges; geographical unit, land area, and population distributions; percent agreement; suitability for analysis; and integration feasibility for national, state, and local cancer research. We referenced 1569 Wisconsin Pancreatic Cancer Registry patients to demonstrate how index choice affects patient categorization.

Results: Six indexes categorized rural and urban areas. Indexes agreed on binary rural-urban designation for 88.8% of the US population. As ternary variables, they agreed for 83.4%. For cancer registry patients, this decreased to 73.4% and 60.4% agreement, respectively. Rural-Urban Continuum Codes (RUCC) performed the best in differentiating metropolitan, micropolitan, and rural counties; availability for retrospective and prospective studies; and continuous coding for analysis.

Conclusions: Urban/rural patient categorization changed with index selection. We conclude that RUCC is an appropriate and feasible rural-urban index to include in cancer research, as it is standardly available in national cancer registries, can be matched to patient’s county of residence for local research, and it had the least amount of fluctuation of the indices analyzed. Utilizing RUCC as a continuous variable across studies with a rural-urban component will increase reproducibility and comparability of results and eliminate rural-urban index choice as a potential source of discrepancy between studies.

Author Affiliations: Morgridge Institute for Research, Madison, Wisconsin (Schiefelbein, Skala); University of Wisconsin-Madison (UW-Madison), Madison, Wis (Krebsbach); Department of Medicine, UW School of Medicine and Public Health (SMPH), Madison, Wis (Taylor, LoConte); Department of Sociology, UW-Madison, Madison, Wis (Haimson, Eason); Department of Surgery, UW SMPH, Madison, Wis (Varley); Department of Biomedical Engineering, UW-Madison, Madison, Wis (Skala); University of Wisconsin Carbone Cancer Center, Madison, Wis (Skala, Eason, LoConte); Department of Community and Environmental Sociology, UW-Madison, Madison, Wis (Eason); UW-Madison Institute for Research on Poverty, Madison, Wis (Eason).
Corresponding Author: Noelle K. LoConte, MD, FASCO, Associate Professor of Medicine, University of Wisconsin, 600 Highland Ave, MC 5666, Madison, WI 53792; phone 608.265.5883; email; ORCID ID 0000-0002-3883-4153
Funding/Support: This project was supported by P30 CA014520 (CCSG Cancer Center Support Grant, University of Wisconsin Carbone Cancer Center), R01 CA211082 (NIH/NCI), R01 CA211082-03S1 (NIH/NCI), and the University of Wisconsin Carbone Cancer Center (UWCCC) Pancreas Cancer Task Force.
Financial Disclosures: None declared.
Acknowledgements: The authors would like to thank the University of Wisconsin Carbone Cancer Center Pancreas Cancer Task Force for the funds to complete this project.
Ethics Approval: The pancreas cancer registry data use was exempt as human subjects research by the University of Wisconsin Health Sciences IRB, ID # 2019-0155, expiration April 26, 2024.
Availability of Data and Materials: The datasets generated and/or analyzed during the current study are not publicly available due to HIPAA restrictions with personal health information for the registry patients but are available from the corresponding author on reasonable request. The other datasets analyzed are publicly available and are referenced as such in the manuscript.
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