Demographic trends in clinical trial withdrawal rate within the Bubble Study: Updated analysis.

71 Background: There are well described barriers to clinical trial participation among varied racial/ethnic and demographic groups. Little is known about clinical trial drop-out rate among these groups. This is an updated analysis of the demographic and clinical characteristics of patients who originally enrolled in the “Bubble Study” clinical trial but then withdrew at a later date. Bubble Study is a non-blinded, prospective observational cohort study designed to assess the adherence rate of adjuvant endocrine therapy among women with early stage breast cancer. Methods: From Aug 2012 to April of 2014, 88 women were enrolled. Demographic data (age, race. insurance status) and treatment factors (stage, surgery type, therapy duration, co-morbidites) were collected. Comorbidities were defined as none, moderate (1-3) or significant (>3.) Descriptive statistics were produced for the entire cohort and the subjects of cohort. Frequencies were compared using a Chi-square test (Fisher’s exact test when expected cell frequencies are small). Results were declared significant at significance level of 5% and all analyses are performed using SAS (2003, 2005). Results: At the time of analysis, 86 patients enrolled (E), 41 of which withdrew (W.) Blacks represented 21% of the total E. Private insurance represented the majority (60.4% of those E and Medicare, Medicaid and Uninsured followed in that order (24.4%, 14% and 1.2% respectively.) There was no significant difference with regards to race and insurance between the E and W group although there was a trend toward a higher rate of W among Blacks (p=0.21). Stage, surgery type or age did not predict for W. Comorbidites had a marginal effect on W (p=0.02) The most common reasons reported for W were financial and/or insurance reasons (22%) and inconvenience of pharmacy pick up (15%.) Conclusions: Demographic characteristics that traditionally predict for under-representation in clinical trial enrollment did not predict for W from the Bubble Study. Although this sample size is small this data may suggest disparities in clinical trial participation are largely due to enrollement rather than withdrawal. Continued analysis of this trial and others will help confirm these findings. Clinical trial information: NCT01694225.