How did exposure to critical access hospitals change Medicare's effect on cancer survival?

Upon turning 65, cancer patients experience the "Medicare Effect' of better outcomes relative to patients nearly 65. Context likely mediates this effect, but so might differential access to care. In response to over 400 rural hospital closures in the 1980s-90 s, in 1997 the US federal government created a Critical Access Hospital (CAH) designation and funding to maintain access to care in rural communities. Despite the intrinsic relationship between CAH and Medicare, it is unknown whether the CAH destinations mitigated or exacerbated the observed disparities in cancer outcomes between patients newly eligible and not yet eligible for Medicare.

Population-based data for this study was obtained from the Surveillance, Epidemiology, and End Results (SEER) program's SEER-13 data (1993-2010). The two primary outcomes measure distant staging at diagnosis and two-year patient survival. We construct a Difference-in-Discontinuities framework test if this "Medicare Effect" on distant staging and survival varies in counties with and without a Critical Access Hospital (CAH), before and after CAH conversion.

Consistent with prior literature, gaining Medicare was associated with reduced probability of distant stage diagnosis and improved two-year survival. Exposure to CAHs did not change Medicare's effect on staging, but did increase Medicare's effect on all-cause survival for males with prostate cancer (Est. =  + 0.019, se = 0.005), and females with lung (+ 0.046, se = 0.021) and colorectal cancer (Est. =  + 0.076, se = 0.026).

Policies improving cancer survival remain warranted for both men and women with, and without Medicare. Sustaining the availability of CAH services remains essential for ensuring equitable access to cancer care.