(ChemotherapyAdvisor) – Lower-income patients of any age are less likely to participate in clinical trials, according to a study in the Journal of Clinical Oncology published online January 7, 2013.

“Heightened awareness of socioeconomic (SES) disparities in access to medical, economic, or other resources is an important and current public policy issue and provided the motivation to investigate potential SES barriers to clinical trial participation,” noted Joseph M. Unger, MS, PhC, of the SWOG Statistical Center, Fred Hutchinson Cancer Research Center, Seattle, WA, and colleagues.

From 2007 to 2011, the investigators surveyed 5,499 patients who had made a treatment decision in the prior 3 months using an Internet-based treatment decision tool designed to assess clinical trial participation patterns according to important SES (income, education) and demographic factors. “Attitudes toward clinical trials were assessed using prespecified items about treatment, treatment tolerability, convenience, and cost,” they noted.

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The survey cohort comprised 2,894 breast (53%), 1,546 prostate (28%), 651 lung (12%), and 408 colorectal cancers (7%); 22% were 65 years of age or older, 2.5% were African American, and 62% were women. Income was reported by 83% of patients and 32% made more than $50,000 annually. Education level was obtained for all patients, of whom 34% reported obtaining at least a 2-year college degree.

Among these patients, “40% discussed clinical trials with their physician, 45% of discussions led to physician offers of clinical trial participation, and 51% of offers led to clinical trial participation. The overall clinical trial participation rate was 9%,” Unger stated.

Using univariate models, those less likely to participate in clinical trials were patients who were older (P=0.002) and with lower income (P=0.001) and lower education (P=0.02).

In a multivariable model, income remained a statistically significant predictor of clinical trial participation (odds ratio, 0.73; P=0.01), with lower income predicting lower trial participation, even in those 65 years of age or older who have universal access to Medicare. “Cost concerns were much more evident among lower-income patients (P<0.001),” they found.

“Improving participation of lower-income patients in clinical trials is important from multiple perspectives,” the authors wrote. “Because clinical trials offer the newest cancer treatments, equal access to this important resource for patients of all income groups is essential. Also, improved lower income participation would allow clinical trials to be conducted more quickly and would better ensure the applicability of trial results to all income levels (ie, generalizability). Understanding that income is related to clinical trial participation could help guide policy decisions aimed at increasing access for lower-income patients.”