Researchers from the SWOG Cancer Research Network, a clinical trials group funded by the National Cancer Institute (NCI), have found that the Affordable Care Act’s (ACA’s) expansion of Medicaid insurance in 2014 was followed by a significant increase in the proportion of patients enrolling in SWOG trials who were covered by Medicaid. "Improved access to clinical trials for more vulnerable patients is critical for improving confidence that trial findings apply to the general cancer population,” the researchers state.

The results are being presented in an oral abstract at the 2022 annual meeting of the American Society of Clinical Oncology (ASCO) in Chicago on June 4 (abstract 6505).

“These findings suggest that the ACA’s Medicaid Expansion may have expanded access to clinical trials,” said Joseph M. Unger, PhD, a SWOG biostatistician and health services researcher with Fred Hutchinson Cancer Center who led the analysis. “This is key to improving enrollment of patients from diverse socioeconomic backgrounds, which could also lead to more reliable trial results.” 

The increase in the use of the Medicaid insurance program after the implementation of the Affordable Care Act (ACA) starting in 2014 has been well documented. It has been less clear  whether this translated to increased participation in clinical trials by patients insured by Medicaid. 

To help answer this question, Unger’s team looked at data from 47,042 adult patients aged 18-64 years who had enrolled to cancer clinical trials conducted by the SWOG Cancer Research Network from 1992 to early 2020. Ten percent of that number – 4,709 patients – were insured by Medicaid.

The researchers found that following the Medicaid expansion, the proportion of SWOG trial participants who had Medicaid insurance rose by 20 percent each year.

In the years before passage of the ACA, this proportion varied annually based on economic conditions, tending to decrease during times of economic growth and low unemployment and to increase during times of high unemployment. Using these and other historical factors, the researchers estimated the participant proportions that would have been expected had Medicaid not been expanded.

They estimated that in February 2020 – the end of the period they studied – the percentage of Medicaid users among SWOG trial participants would have been 7.4 percent. By contrast, in February 2020 the actual percentage of SWOG trial participants on Medicaid was 20.8 percent, an almost threefold increase over the proportion that would have been expected.

The analysis revealed a notable gender difference in the rate at which participation of Medicaid patients increased. The odds of trial-enrolled women using Medicaid insurance rose by 29 percent per year after Medicaid expansion, while the odds of trial-enrolled men using Medicaid increased by only 7 percent per year. 

The analysis also showed a clear distinction between states that implemented Medicaid expansion in 2014 or 2015 and those that did not. Among trial participants from the former states, the odds of patients using Medicaid insurance increased by 27 percent annually, whereas for participants from other states the annual increase was 7 percent. 

The authors note that their results suggest the recently enacted Clinical Treatment Act may further increase participation in trials by those with Medicaid insurance. That law requires states to cover routine care costs for Medicaid patients on clinical trials.

“Not all state Medicaid programs have required that Medicaid cover the routine care costs of participating in a clinical trial,” Dr. Unger said. “The Clinical Treatment Act changes that. Our findings imply that patients from states that have had more limited Medicaid insurance may begin to see similar improvements in access to clinical trials.”

The SWOG-led trials the team analyzed are supported by the NCI, part of the National Institutes of Health (NIH), and conducted by the NIH-funded National Clinical Trials Network (NCTN) and the NCI Community Oncology Research Program (NCORP).

The team’s work was funded by the NIH/NCI through grants CA189974, CA180888, and CA180819; in part by American Cancer Society Research Scholar Grant 134589-RSGI-20-027-01-CPHPS; and by The Hope Foundation for Cancer Research. 

Additional authors on this work included Hong Xiao, PhD, and Riha Vaidya, PhD, of SWOG Statistics and Data Management Center and Fred Hutchinson Cancer Center, and Dawn L. Hershman, MD, MS, of Columbia University.

Unger JM et al, “The Medicaid Expansion of the Affordable Care Act and Participation of Patients with Medicaid in SWOG Cancer Clinical Trials,”  J Clin Oncol 40, 2022 (suppl 16; abstr 6505)


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