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Low Income Is a Barrier to Clinical Trial Enrollment, Study Suggests

, by NCI Staff

Patient income levels may influence clinical trial participation, a new study finds.

Credit: iStock

In a recent survey study, researchers affiliated with the NCI Community Oncology Research Program (NCORP) found that patients with annual household incomes below $50,000 were less likely to participate in a cancer clinical trial than those with higher incomes. Participation rates were lowest for patients with annual incomes of less than $20,000.

The findings were published October 15 in JAMA Oncology.

Led by Joseph M. Unger, Ph.D., of the Fred Hutchinson Cancer Research Center in Seattle, the study used data from a 2012 survey of cancer patients who were eligible for participating in clinical trials at eight geographically diverse cancer treatment centers and for whom income data were available.

Seventeen percent of patients with annual household incomes of $50,000 or more participated in a trial, the researchers reported, compared with 13 percent of patients with incomes of $50,000 or less. Participation rates were just 11 percent for patients with annual household incomes below $20,000.

A key feature of the study was that patients were enrolled before they had made any decisions about whether to join a trial, Dr. Unger noted. The findings confirm those of a previous observational study by Dr. Unger and his colleagues, which found that patients with annual household incomes below $50,000 were 27 percent less likely than patients with higher incomes to participate in clinical trials.

“Although each study had its own limitations and neither alone was definitive, the fact that very similar patterns were identified in two sequential, independent studies provides compelling evidence that the observation of income disparities in clinical trial enrollment may be valid,” Dr. Unger said.

“The main reason that trials fail to complete is insufficient accrual,” he continued. “If more lower-income patients enroll in trials, accrual will finish more quickly, and overall the time to conduct the trial and get the results will be faster.”

According to Worta McCaskill-Stevens, M.D., chief of NCI’s Community Oncology and Prevention Trials Research Group, a key strength of the study was that 80 percent of the participants were willing to disclose their income status.

“This truly helps us understand one of the important social determinants of those who participate in clinical trials,” she said. When enrolling patients in a trial, Dr. McCaskill-Stevens noted, investigators must consider that some potential participants may have experienced a lifetime of poverty, “which can be very self-limiting in terms of enrollment interest and capability.”

Data on how income affects clinical trial accrual have been lacking, Dr. McCaskill-Stevens continued. To address this issue, NCI plans to collect enhanced demographic data in NCORP cancer control and prevention trials.

“This new study gives us an indication of what data can be collected, but we will need to be even more comprehensive in our data collection and analysis going forward,” she said.

A better understanding of the economics of clinical trials enrollment is especially important now, Dr. McCaskill-Stevens added, because NCI will soon require that cancer control and prevention trials that include predominantly pediatric, adolescent, and young adult patients track factors such as race and method of payment for their non-trial costs. These factors haven’t previously been documented in most trial results.

While this analysis primarily examined enrollment in trials in people younger than age 65, those 65 and older are a growing demographic group and poverty is also increasing among that age group.

“Poverty forces those over 65 years of age to make decisions that often diminish their adherence to interventions to treat cancer and its side effects, which is another important factor we need to study more carefully in the future,” said Dr. McCaskill-Stevens.

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