Populations in U.S. counties defined as more vulnerable based on social factors—including socioeconomic status and racial and ethnic minority status—may be significantly less likely to receive timely breast, cervical, and colorectal cancer screenings, according to a recent study published by Bauer et al in JAMA Network Open.
Disparities in screening rates were highly associated with a county’s social vulnerability index—a tool that uses U.S. Census data to determine social vulnerability at a county or census tract level. The social vulnerability index is calculated using factors such as socioeconomic status, household composition, racial and ethnic minority status, housing type, transportation access, language barriers, and other common factors in an area’s population. The index score helps public health officials and local planners better prepare for and respond to emergency events like hurricanes and disease outbreaks, which disproportionately affect areas with higher social vulnerability indexes.
“We found that counties with higher [social vulnerability index] scores had significantly lower screening rates for all three types of cancer [studied],” said study lead Ryan Suk, PhD, Assistant Professor of Management, Policy, and Community Health at the School of Public Health at The University of Texas Health Science Center at Houston. “These findings suggest that geographically targeted public health interventions could be further informed and improved by a composite measure reflecting the multidimensional measure of area-level social determinants of health.”
Study Methods and Results
The population-based, cross-sectional study used county-level information from the Centers for Disease Control and Prevention’s (CDC) PLACES: Local Data for Public Health and social vulnerability index data sets from 2018. Analyses were conducted from October 2021 to February 2022.
Researchers discovered regional disparities in cancer screening rates across 3,141 U.S. counties ranging from the lowest-performing to the highest-performing county: including 54.0% to 81.8% for breast cancer screening, 69.9% to 89.7% for cervical cancer screening, and 39.8% to 74.4% for colorectal cancer screening.
“Even though cervical cancer screening rates are high overall, that doesn’t mean that is true everywhere,” Dr. Suk said. “Some populations have very low uptake, while in other areas, the cancer screening rate is higher than the national target rate. That’s why we have to focus on these differences by social determinants of health and not only overall average values.”
Other key findings included the following:
- The likelihood of undergoing cancer screening in the most vulnerable counties (the highest fifth) compared with the least vulnerable counties (the lowest fifth) was 14% lower for breast cancer, 20% lower for cervical cancer, and 28% lower for colorectal cancer.
- Some other area-level factors, such as rural/urban status and health-care access in the county, were also associated with cancer screening rates. However, these factors did not further explain the geographic variation of the cancer screenings and did not change the association between social vulnerability and cancer screening rates.
Generally, all three cancer screening rates were higher among counties on the East Coast and West Coast and lower in the South.
“Our study emphasizes the benefit of using geospatial analysis in population health for cancer research. It provides a powerful analytical tool to identify target areas for improving cancer prevention and reducing disparities,” said lead study author Cici Bauer, PhD, Associate Professor of Biostatistics and Data Science at the School of Public Health at The University of Texas Health Science Center at Houston. “It also provides a way to understand how various social determinants of health may impact the cancer-related outcomes.”
Overall, colorectal cancer screening rates were low throughout the United States, Dr. Suk said, meaning public health experts should emphasize the importance of these screenings on a broad scale.
Disclosure: For full disclosures of the study authors, visit jamanetwork.com.
