Annual cases of colon cancer by age group after Medicaid expansion in the USA in 2014: a difference-in-differences study

Background
Studies examining the association between Medicaid expansion (ME) under the Affordable Care Act (ACA) and colon cancer incidence have produced mixed results.

Objective
To re-visit the association between the ACA-ME and annual cases of colon cancer.

Design
Difference-in-differences (DiD).

Setting
The primary analyses used data from the National Cancer Database from 2010 to 2018, a hospital-based cancer registry in the USA. We also conducted exploratory analyses using data from the Surveillance, Epidemiology and End Results (SEER) registry.

Patients
Patients aged 40 and older with newly diagnosed colon cancer.

Measurements
The primary outcome was the percent change in colon cancer of all stages. Secondary outcomes were percent changes in stage I and stage IV cases.

Results
Among those aged 40–49, we observed a statistically significant greater increase in stage I colon cancer in expansion states relative to non-expansion states (DiD (percent change) 9.7% (95% CI, 2.5% to 17.4%)). In those aged 50–64, we did not observe statistically significant differences between the two state groups in any of the outcomes. Among those aged 65+, we observed a statistically significant relative decrease for all stages in ACA-ME states (–1.0% (95% CI, –1.0% to –3.0%)) and for stage IV (–3.0% (95% CI, –2.0% to –5.0%)). We explored our findings among younger individuals (

Leggi
Giugno 2025