Impact of insurance and neighborhood socioeconomic status on clinical outcomes in therapeutic clinical trials for breast cancer

The objective of this study was to evaluate the impact of insurance and neighborhood SES (nSES) on chemotherapy completion and overall mortality among participants in breast cancer clinical trials. The data sources for this study were two adjuvant breast cancer trials (ECOG E1199 and E5103) collectively including 9790 women. Insurance status at trial registration was categorized into private, government (Medicaid, Medicare, and other government type insurance), and self-pay. An Agency for Healthcare Research Quality (AHRQ) nSES index was calculated using residential zip codes linked to county level data on occupation, income, poverty, wealth, education, and crowding. Logistic regression and Cox Proportional Hazard models estimated odds ratios (OR) for chemotherapy treatment completion and hazard ratios (HR) for mortality, respectively, for insurance status and nSES. The models adjusted for: race, age, tumor size, nodal status, hormone receptor status, and primary surgery. The majority of patients had private insurance at trial registration: E1199: 85.6% (4154/4854) and E5103: 82.4% (3987/4836); median SES index was 53.8 (range: 41.8-66.8) and 54.1 (range: 44.5-66.1), respectively. Patients with government insurance were less likely to complete chemotherapy treatment (E1199 OR (95%CI): 0.73 (0.57-0.94); E5103 0.76 (0.64-0.91)) and had an increased risk of death (E1199 HR (95%CI): 1.44 (1.22-1.70); E5103 1.29 (1.06-1.58)) compared to the privately insured patients. There was no association between nSES and chemotherapy completion or overall mortality. Patients with government insurance at trial registration appeared to face barriers in chemotherapy completion and had a higher overall mortality compared to their privately insured counterparts.