Self-Reports of 6-Mercaptopurine Intake in Childhood Acute Lymphoblastic Leukemia Unreliable

Phoebe Starr

May 2016, Vol 7, No 4 - Hematologic Malignancies

Approximately 40% of children with acute lymphoblastic leukemia (ALL) fail to take 6-mercaptopurine (6-MP) as prescribed, and a sizable majority of parents and children with ALL overreport the intake of a critical drug for maintaining remission, according to a study reported by lead investigator Wendy Landier, PhD, RN, NP, Children’s of Alabama, Birmingham, and colleagues at ASH 2015. The study suggests that electronic reporting using TrackCap, a medication event monitoring system (MEMS), is more reliable than self-reports. Approximately 88% of parents of children with ALL and children with ALL aged >12 years overreported the number of days 6-MP was taken, and 24% overreported by ≥5 days monthly in >50% of the study months. “Subjective overreporting of 6-MP adherence during maintenance therapy is common for children with ALL, particularly in nonadherent patients, and should be viewed with caution,” said Dr Landier. She explained that approximately 2 years of maintenance chemotherapy that includes daily oral 6-MP are needed to achieve durable remission in childhood ALL. The team previously showed that adherence rates of <95% are associated with a 3.7 times higher risk for relapse. The Children’s Oncology Group AALL03N1 study was a prospective study designed to compare self-reported 6-MP intake (by parents of children aged <12 years and by patients aged ≥12 years) versus electronic monitoring using TrackCap, a MEMS electronic system that records each opening of the medication bottle. At the end of each of the 4 study months, the 6-MP intake according to self-reports and to electronic monitoring were compared. The study analyzed a total of 1344 patient-months of self-reports and MEMS data. The study enrolled 416 patients with a median age of 6 years. Of these patients, 38% had high-risk disease according to National Cancer Institute criteria, and 40.4% were found to be nonadherent. A total of 66% of the patients in the study were male, and 61% were from families with paternal education less than college. Overall, 12% of the patients were “perfect reporters,” 24% were overreporters by ≥5 days monthly in ≥2 of the 4 months, <1% underreported, and 64% of the patients were categorized as other. At the end of each month, a significant difference was found between the self-reporting and electronic reporting groups (P <.001). At all time points, the median number of self-reports was higher than that for MEMS. A multivariate analysis identified 4 factors associated with overreporting—age >12 years, nonwhite race, paternal education less than college, and nonadherence. For each increasing year of the child’s age, the risk for overreporting increased by 7%. The children’s self-reports were more likely to overestimate 6-MP intake than the parents’ reporting. Furthermore, nonadherent patients were much more likely to be overreporters, with 2% of perfect reporters being nonadherent and >80% of overreporters being nonadherent. Dr Landier and colleagues plan to develop future interventions to educate parents and children with ALL about the importance of adherence.