Geographic variation in colorectal cancer survival and the role of small-area socioeconomic deprivation: a multilevel survival analysis of the NIH-AARP Diet and Health Study Cohort

Abstract

Adverse socioeconomic conditions, at both the individual and the neighborhood level, increase the risk of colorectal cancer (CRC) death, but little is known regarding whether CRC survival varies geographically and the extent to which area-level socioeconomic deprivation affects this geographic variation. Using data from the National Institutes of Health (NIH)-AARP Diet and Health Study, the authors examined geographic variation and the role of area-level socioeconomic deprivation in CRC survival. CRC cases (n = 7,024), identified during 1995-2003, were followed for their CRC-specific vital status through 2005 and overall vital status through 2006. Bayesian multilevel survival models showed that there was significant geographic variation in overall (variance = 0.2, 95% confidence interval (CI): 0.1, 0.2) and CRC-specific (variance = 0.3, 95% CI: 0.1, 0.4) risk of death. More socioeconomically deprived neighborhoods had a higher overall risk of death (most deprived quartile vs. least deprived: hazard ratio = 1.2, 95% CI: 1.1, 1.4) and a higher CRC-specific risk of death (most deprived quartile vs. least deprived: hazard ratio = 1.2, 95% CI: 1.1, 1.5). However, neighborhood socioeconomic deprivation did not account for the geographic variation in overall and CRC-specific risks of death. In future studies, investigators should evaluate other neighborhood characteristics to help explain geographic heterogeneity in CRC survival. Such research could facilitate interventions for reducing geographic disparity in CRC survival.

Figure 1.

Kaplan-Meier survival curves for colorectal cancer (CRC) patients in the NIH-AARP Diet and Health Study, 1995–2005/2006. Neighborhood socioeconomic deprivation score was categorized into 4 quartiles (least deprived (quartile 1) to most deprived (quartile 4)). A) All-cause survival, 1995–December 31, 2006; B) CRC-specific survival, 1995–December 31, 2005. The log-rank test indicated highly significant statistical differences (P = 0.001 for all-cause survival and P = 0.008 for CRC survival). NIH, National Institutes of Health.