Study Examines Medicaid Expansion and IBD Mortality

A new study presented at this year’s American College of Gastroenterology examined the relationship between Medicaid expansion and inflammatory bowel disease (IBD)-related mortality.

“Our study found that although Medicaid expansion was associated with a smaller increase in IBD-related mortality, the difference was not statistically significant,” explains Leyla Maric, MD, Associate Medical Director, Inflammatory Bowel Disease Center, Cleveland Clinic Weston Hospital, and one of the study authors. “While the research cannot establish that expansion improved mortality rates, the findings point to the need for patient-level research on barriers to timely GI care.”

Comparing mortality trends across states

More than 3 million people are affected by IBD — a condition associated with significant morbidity and mortality. In 2014, the Affordable Care Act expanded Medicaid’s coverage to millions of low-income Americans, potentially improving access to GI care and biologic therapies.

To better understand the impact of Medicaid expansion, the research group examined state-level IBD mortality data from 1999 to 2024. They extracted age-adjusted and crude mortality rates per 100,000 from all 50 states as well as Washington, D.C., which gave them 849 usable state-year observations.

States were then grouped as either expansion (n = 32) or non-expansion (n = 19) based on whether they had adopted Medicaid expansion by January 1, 2016.

“We excluded the years 2014 to 2016 from our study, since Medicaid expansion was being introduced at different times across states,” explains Dr. Maric. “This staggered implementation period would have confounded our analysis. Additionally, we defined the post-expansion period as 2017 to 2024.”

The group used a two-way fixed effects difference-in-differences model, which included state and year fixed effects with cluster-robust standard errors.

“The data groups already had different mortality rates before the expansion, so simply subtracting the rates afterward could confuse an old difference with a new difference,” says Dr. Maric. “So instead, we measured the before-to-after change within each group and compared those two changes.”

Smaller mortality increase in expansion states

The researchers found that both groups showed parallel IBD mortality trends before expansion. Baseline IBD mortality (1999 to 2013) was 0.313 per 100,000 in expansion states and 0.294 per 100,000 in non-expansion states. Medicaid expansion was not associated with a significant reduction in IBD mortality rates (DiD: .0023; 95% CI: .029 to .025; P = .869). However, expansion states experienced a smaller post-expansion mortality increase than non-expansion states (8.3% vs 14.6%).

“It’s important to note that although our study did not show a statistically significant mortality benefit from Medicaid expansion, the absence of significance does not prove that expansion had no benefit,” says Dr. Maric. “Insurance is just one piece of the puzzle — patients might still face limited GI specialist availability, prior authorization delays, medication access issues and difficulty accessing care.”

The group’s state-level analyses also identified Maine (0.70), West Virginia (0.54) and Oregon (0.50) as having the highest post-expansion mortality. Dr. Maric says the reason for this finding is still unclear, but the group is looking further into what could be driving the higher mortality rates in these states.

State-level data limits conclusions

One of the biggest challenges with the study, according to the research group, was its reliance on state-level mortality data rather than patient-level records. State-level data does not allow linking a patient’s diagnosis, treatment, follow-up or outcomes over time, which limits insight into how care is delivered and how it impacts outcomes.

“Having Medicaid coverage doesn’t actually mean that care was delivered,” says Dr. Maric. “The state-level data doesn’t provide insight into the intermediate steps between gaining coverage and whether a patient actually receives timely care.”

The mortality rates also reflect each state’s overall population rather than exclusively patients with IBD. This makes it harder to isolate disease-specific care effects or establish causation.

Priorities for future research

“Our study raises a practical question: After someone gains insurance, can they receive effective treatment promptly?” says Dr. Maric. “We did not detect a clear and statistically significant mortality benefit in the study, but that does not prove there was none. The smaller rise in mortality is still worth reporting as a descriptive finding.”

Dr. Maric says prior authorization delays are another potential barrier the group may examine.

“Although the findings were not statistically significant, they help identify questions for future patient-level studies,” she says. “The next step is to examine whether coverage translates into timely specialty care and effective treatment.”