Patient income level and cancer clinical trial participation

Abstract

Purpose: Studies have shown an association between socioeconomic status (SES) and quality of oncology care, but less is known about the impact of patient SES on clinical trial participation.

Patients and methods: We assessed clinical trial participation patterns according to important SES (income, education) and demographic factors in a large sample of patients surveyed via an Internet-based treatment decision tool. Logistic regression, conditioning on type of cancer, was used. Attitudes toward clinical trials were assessed using prespecified items about treatment, treatment tolerability, convenience, and cost.

Results: From 2007 to 2011, 5,499 patients were successfully surveyed. Forty percent 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%. In univariate models, older patients (P = .002) and patients with lower income (P = .001) and education (P = .02) were less likely to participate in clinical trials. In a multivariable model, income remained a statistically significant predictor of clinical trial participation (odds ratio, 0.73; 95% CI, 0.57 to 0.94; P = .01). Even in patients age ≥ 65 years, who have universal access to Medicare, lower income predicted lower trial participation. Cost concerns were much more evident among lower-income patients (P < .001).

Conclusion: Lower-income patients were less likely to participate in clinical trials, even when considering age group. A better understanding of why income is a barrier may help identify ways to make clinical trials better available to all patients and would increase the generalizability of clinical trial results across all income levels.

Fig 1.

Geographic distribution of survey participants. The legend shows the proportion of survey participants by geographic region compared with proportions in nonparticipants and in the US adult population.

Fig 2.

Patient flow diagram indicating decision-making patterns about clinical trial (CT) participation. A total of 77,752 survey invitations were sent, and 6,259 were returned; 760 respondents had not made a treatment decision within the 3 months since their initial registration on the NexCura Web site, leaving 5,499 evaluable patients. For the 760 respondents who had not made a treatment decision within the 3 months since their initial registration, most had made a treatment decision earlier than 3 months before (65%) or were recently diagnosed but still undecided about treatment (15%).

Fig 3.

Forest plot of the association of income and clinical trial participation by each study factor. Each square represents an odds ratio (OR), and each horizontal line is the 95% CI. The vertical line is the line of equal odds. For lower-income individuals, the odds of clinical trial participation were consistently lower (that is, to the left of the line of equal odds) within nearly all subgroups of all the factors included in this analysis, indicating that the association between income and participation was independent of subgroup membership.

Fig 4.

Reasons for declining to participate in clinical trials. Among patients who were offered a clinical trial but did not participate (n = 482), the most common reasons cited for nonparticipation were treatment-related concerns (ie, fear of random assignment, did not want the specified protocol treatment, and so on). Other reasons that differed by socioeconomic or demographic factors included the following: age: older patients were less concerned about travel related to clinical trial participation (P = .02), less concerned about how to pay for clinical trial participation (P = .04), and less concerned about time and effort related to clinical trial participation (P = .04); sex: women were less likely to have family and friends opposed to their clinical trial participation (P = .03); income: lower-income patients were more concerned about how to pay for clinical trial participation (P = .01), less concerned that a research protocol would determine their treatment choice (P = .01), less likely to have family or friends opposed to their clinical trial participation (P = .03), and less concerned about random treatment assignment in a clinical trial (P = .04); and education: lower-education patients were less concerned about clinical trial adverse effects (P = .05).