Colorectal Cancer Incidence and Mortality in Texas 1990–1992: A Comparison of Rural Classifications

Abstract

Although cancer incidence and mortality rates are known to be higher in urban populations, more unstaged tumors and later staged cancer are diagnosed in rural populations. Most investigators have used a dichotomous definition of urban and rural in studying these populations, and they have not considered whether a more detailed categorization of rural areas could influence their findings. The objective of this study was to evaluate colorectal cancer incidence and mortality rates in Texas from 1990 to 1992 by using a dichotomous definition (Metropolitan Area vs. Nonmetropolitan Area [MA/non-MA]) and two more detailed rural classifications (the Rural-Urban Continuum Code [RUCC] and the Urban Influence Code [UIC]). Cancer data were obtained from the Texas Cancer Registry for 1990 to 1992 and supplemented with data from the Texas State Department of Vital Statistics (mortality), the US Census Bureau (age, gender, race) and the Area Resource File (rural and urban definitions). Incidence and mortality rates, age-adjusted to the 1970 US standard population, were calculated for non-Hispanic White, African American, and Hispanic males and females. Results revealed a nonlinear relationship between rural category and colorectal cancer incidence or mortality for all races. Applying the MA definition yielded rates in the middle of the ranges obtained with using RUCC or UIC classifications and most closely reflected the result for non-Hispanic Whites using the more detailed scales. Our results suggest that a dichotomous definition of rural and urban may mask important variation in colorectal cancer incidence and mortality rates within rural areas.

Defining Urban and Rural Areas in U.S. Epidemiologic Studies

“…46 Hawley used both RUCCs and UICs to describe the variation in colon cancer incidence and mortality rates in Texas and concluded that finer delineations on the rural end of the scales revealed heterogeneity in rates with respect to African-Americans. 47 Similarly, we found much lower rates of mammography-detected breast cancer in North Carolina (NC) in the most rural areas using the UIC taxonomy; these differences would have been attenuated had we used a dichotomous measure. 48 Researchers have also grouped the scales.…”

Rurality and Other Determinants of Early Colorectal Cancer Diagnosis in Nebraska: A 6‐Year Cancer Registry Study, 1998‐2003

“…To our knowledge, this is the first population‐based study in Nebraska using data from the state's cancer registry that used the 3‐level OMB classification scheme (rural [non‐core] nonmetropolitan, micropolitan nonmetropolitan, and metropolitan) and other determinants of early‐stage CRC diagnosis. Unlike previous studies that used dichotomous schemes, 3,4,6,7,22 we used the recent 2003 OMB classification, 23–27 and controlled for other confounders of early‐stage CRC diagnosis, such as socioeconomic status (income and education), health insurance, anatomic site, and provider‐to‐population ratio, in 1 multivariate model. The reported findings of rural/micropolitan differences but no rural/metropolitan differences for early‐stage ( in situ /local) were upheld for “ in situ ” CRC diagnosis (data not shown), which supports the robustness of our results.…”

“…Dichotomous definition of rural‐urban communities in previous studies 3,4,6,7,22 may mask important differences in CRC incidence, 22 and misclassify a proportion of the rural population that may be affected by nonmetropolitan diversity 23 . The federal government frequently uses the county‐based OMB metropolitan and nonmetropolitan classifications as policy tools in determining eligibility and reimbursement for many federal programs 24 .…”

“…The differences in our findings from those of previous studies may be explained by the OMB coding we used. The OMB coding is a more recent measure used in health care research 24,27 compared with the dichotomous rural‐urban measure used in earlier studies 3,4,6,7,22 …”

Patients Diagnosed with Colorectal Cancer in Rural Areas in Arizona Typically Present with Higher Stage Disease

“…Despite the efforts, discrimination based on socioeconomic status and location continues to play an important role in colorectal cancer outcomes. According to a recent review, one half of patients in rural areas are not up to date on colorectal cancer screening [10,11]. Moreover, marked disparities persist, with lower rates of colorectal cancer screening among racial and ethnic minorities, individuals with lower household income, lower levels of education, the uninsured, and individuals who were not born in the United States [12-15].…”