Introduction:

The impact of the Affordable Care Act’s Medicaid expansion on prostate cancer is a research topic primed for investigation. Previous studies have shown that Medicaid expansion is associated with a decrease in the uninsured across the cancer population in aggregate, and there is separate evidence that suggests having insurance may improve outcomes in prostate cancer. Our study analyzes if Medicaid expansion is associated with changes not only in the insurance status of prostate cancer patients, but also in their stage at diagnosis and their receipt of various treatments, metrics that could explain a link between insurance and improved outcomes. Given that Medicaid expansion is an intervention targeted at persons of low-income, it also presents an opportunity to reduce the known socioeconomic disparities in prostate cancer outcomes.

Methods:

Our sample consists of all adults aged 18-64 years with a new primary diagnosis of prostate cancer from the National Cancer Database between January 1, 2011 - December 31, 2016. We performed a difference-in-differences (DD) regression analysis, with patients in states that expanded Medicaid as the intervention group, and patients in non-expansion states as the control group. Our outcomes were the percentage point change (DD) in insurance status, early stage diagnosis, and receipt of treatment (active surveillance for localized low risk disease and receipt of prostatectomy, radiation, or hormone therapy for high risk localized disease). We performed a sub-analysis using the same outcomes but with the sample limited to the low-income population that was eligible for Medcaid expansion, defined as <139% of the Federal Poverty Level. 

Results:

A total of 220,749 cases of prostate cancer were identified using our criteria. We found that Medicaid expansion was associated with a net 0.8 percentage point (ppt) decrease (95% CI: 0.5-1.1) in the proportion of patients who were uninsured, and a net 3.7 ppt increase (95% CI: 3.4-4.1) in the proporiton with Medicaid. We also found that Medicaid expansion was associated with a 3.0 ppt (95% CI: 0.3-5.7) increase in the proportion of prostate cancer patients who are diagnosed as NCCN very-low or low risk. When assessing associations between Medicaid expansion and receipt of treatment, we found no association between expansion and receipt of treatment for NCCN intermediate and high risk disease groups, but a 4.3 ppt net increase (95% CI: 3.2-5.5) in the receipt of active surveillance for very-low and low risk disease groups. These associations were all increased in magnitude in the low-income subgroup analysis.

Conclusion:

Our study is consistent with previous work across aggregated cancer populations that suggests Medicaid expansion is associated with a higher proportion of cancer patients being insured. What is new and more significant is the finding that Medicaid expansion is also associated with further "downstream" metrics in the cancer treatment pathway: diagnosis and treatment. Our data suggest that the use of active surveillance has decreased across both expansion and non-expansion states, but that expansion of Medicaid is associated with less of a decrease. Furthermore, the use of active surveillance for low-risk disease is increasing across the country, but Medicaid expansion is assocaited with a larger increase. These trends are present across the income spectrum, but they are larger in magnitude in the low-income population. This study therefore suggests that Medicaid expansion may have an impact in reducing socioeconomic inequalities in prostate cancer care and outcomes.

Funding: This project was supported by grant number K12HS026372 from the Agency for Healthcare Research and Quality. The content is solely the responsibility of the authors and does not necessarily represent the official views of the Agency for Healthcare Research and Quality