Multiplicative disadvantage of being an unmarried and inadequately insured woman living in poverty with colon cancer: historical cohort exploration in California

BACKGROUND Many Americans diagnosed with colon cancer do not receive indicated chemotherapy. Certain unmarried women may be particularly disadvantaged. A 3-way interaction of the multiplicative disadvantages of being an unmarried and inadequately insured woman living in poverty was explored. METHODS California registry data were analyzed for 2,319 women diagnosed with stage II to IV colon cancer between 1996 and 2000 and followed until 2014. Socioeconomic data from the 2000 census classified neighborhoods as high poverty (≥30% of households poor), middle (5-29%) or low poverty (<5% poor). Primary health insurance was private, Medicare, Medicaid or none. Comparisons of chemotherapy rates used standardized rate ratios (RR). We respectively used logistic and Cox regression models to assess chemotherapy and survival. RESULTS A statistically significant 3-way marital status by health insurance by poverty interaction effect on chemotherapy receipt was observed. Chemotherapy rates did not differ between unmarried (39.0%) and married (39.7%) women who lived in lower poverty neighborhoods and were privately insured. But unmarried women (27.3%) were 26% less likely to receive chemotherapy than were married women (37.1%, RR = 0.74, 95% CI 0.58, 0.95) who lived in high poverty neighborhoods and were publicly insured or uninsured. When this interaction and the main effects of health insurance, poverty and chemotherapy were accounted for, survival did not differ by marital status. CONCLUSIONS The multiplicative barrier to colon cancer care that results from being inadequately insured and living in poverty is worse for unmarried than married women. Poverty is more prevalent among unmarried women and they have fewer assets so they are probably less able to absorb the indirect and direct, but uncovered, costs of colon cancer care. There seem to be structural inequities related to the institutions of marriage, work and health care that particularly disadvantage unmarried women that policy makers ought to be cognizant of as future reforms of the American health care system are considered.