Compliance with patient-reported outcomes in multicenter clinical trials: methodologic and practical approaches

This report describes interventions undertaken by the National Surgical Adjuvant Breast and Bowel Project (NSABP) to improve compliance with patient-reported outcome (PRO) assessments in the setting of multicenter cancer clinical trials. We describe the effectiveness of several interventions and of observational factors.

PRO submission rates were analyzed for the following three NSABP protocols: the Study of Raloxifene and Tamoxifen (STAR), B-32, and B-35. Institutions participating in protocol B-35 were randomly assigned to receive automated reminders of upcoming assessments or not. Compliance was analyzed with a logistic repeated measures mixed modeling.

Compliance was high in the three protocols, with rates greater than 80% for nearly all time points. Institutions were a significant source of variability (P < .01). The largest institutions had the highest compliance in STAR (odds ratio [OR] = 0.68 for < 50 participants enrolled and OR = 0.82 for 50 to 99 participants enrolled v larger institutions; P < .001). Midsized institutions had highest compliance in B-32 (OR = 4.63 for 31 to 50 patients enrolled and OR = 3.12 for > 50 patients enrolled v small institutions; P = .007). Compliance increased with participant age in STAR (OR = 0.57, 0.89, and 1.01 for ages < 50, 50 to 60, and 60 to 70 years, respectively, v > 70 years; P < .001). Race was significant in B-32 (OR = 2.63 for white v nonwhite; P < .001) and in STAR (OR = 1.41 for white v nonwhite; P < .001). Treatment group was significant in B-32 (OR = 0.74; P = .006). The B-35 prospective reminder did not improve compliance significantly (P = .30), but in B-32, delinquency sanctions were significant (OR = 1.56; P = .007).

Compliance in NSABP PRO studies is higher now than a decade ago. Results for compliance initiatives were mixed. Age and race are important factors, but institutional variation remains significant and largely unexplained.