Impact Of Medicaid Expansion On Women With Gynecologic Cancer: A Difference-In-Difference Analysis

Abstract [from journal]

Background: Women with gynecologic cancer face socioeconomic disparities in care that impact survival outcomes. The Affordable Care Act offered states the option to expand Medicaid enrollment eligibility criteria as a means of improving timely and affordable access to care for the most vulnerable. Variable uptake of expansion by states created a natural experiment, allowing for quasi-experimental methods, which offer more unbiased estimates of treatment effects from retrospective data than traditional regression adjustment.

Objective: We sought to use a quasi-experimental, difference-in-difference framework to create unbiased estimates of impact of Medicaid expansion on women with gynecologic cancer.

Study design: We performed a quasi-experimental retrospective cohort study from National Cancer Database files for women with invasive cancers of the uterus, ovary and fallopian tube, cervix, vagina, and vulva diagnosed 2008-2016. Using a marker for state Medicaid expansion status, we created difference-in-difference models to assess the impact of Medicaid expansion on outcomes of access to and timeliness of care. We excluded women under 40 due to suppression of the state Medicaid expansions status in the data, and women 65 and over due to universal Medicare coverage availability. Our primary outcome was rate of uninsurance at diagnosis. Secondary outcomes included Medicaid coverage, early-stage diagnosis, treatment at academic facility, and any treatment or surgery within 30 days of diagnosis. Models were run within multiple subgroups, and on a propensity-matched cohort to assess robustness of treatment estimates. The assumption of parallel trends was assessed with event study time-plots.

Results: Our sample included 335,063 women. Among this cohort, 121,449 were from non-expansion states, and 213,614 from expansion states, with 79,886 post-treatment cases diagnosed after expansion took full effect in expansion states. Groups had minor differences in demographics, and we found occasional pre-period event study coefficients diverging from the mean, but outcome trends were generally similar between expansion and non-expansion states in the pre-period, satisfying the necessary assumption for difference-in-difference analysis. In a basic difference-in-difference model, January 2014 Medicaid expansion was associated with significant increases in insurance at diagnosis, treatment at academic facility, and treatment within 30 days of diagnosis. In an adjusted model including all states and accounting for variable expansion implementation time, there was a significant treatment effect of Medicaid expansion for reduction in uninsurance at diagnosis (-2.00%; 95%CI -2.3- -1.7; p<0.001), and increases in early stage diagnosis (0.80%; 95%CI 0.2-1.4; p=0.02), treatment at academic facility (0.83%; 95%CI 0.1-1.5; p=0.02), treatment within 30 days (1.62%; 95%CI 1.0-2.3; p<0.001), and surgery within 30 days (1.54%; 95%CI 0.8-2.3; p<0.001). Particularly large gains were estimated for women living in low-income zip codes, Hispanic women, and women with cervical cancer. Estimates from subgroup and propensity-matched cohorts were generally consistent for all outcomes besides early stage diagnosis and treatment within 30 days.

Conclusion: Medicaid expansion was significantly associated with gains in access and timeliness of treatment for non-elderly women with gynecologic cancer. Implementation of Medicaid expansion could greatly benefit women in non-expansion states. Gynecologists and gynecologic oncologists should advocate for Medicaid expansion as a means of improving outcomes and reducing socioeconomic and racial disparities.