Adherence to 6MP at <90% was associated with a 3.1-fold increased risk of relapse in a multiracial cohort of children with ALL.
46% of African Americans and 28% of Asians as compared with 14% of non-Hispanic whites were non-adherers (p<0.0001).
Durable remissions in children with acute lymphoblastic leukemia (ALL) require a two-year maintenance phase that includes daily oral 6-mercaptopurine (6MP). Adherence to oral 6MP among Asian and African American children with ALL is unknown. We enrolled 298 children with ALL (71 Asians, 68 African Americans, and 159 non-Hispanic whites) receiving oral 6MP for the maintenance phase. Adherence was measured electronically using Medication Event Monitoring System for 39,794 person-days. Adherence declined from 94.8% (Month 1) to 91.3% (Month 5, p<0.0001). Adherence rates were significantly (p<0.0001) lower in Asians (86.1%±3.1%) and African Americans (86.4%±2.4%), as compared with non-Hispanic whites (95.8%±0.6%). Race-specific sociodemographic characteristics helped explain poor adherence (African Americans: low maternal education, single-parent/multiple-children households; Asians: low-income households; both Asians and African Americans: households without mothers as full-time caregivers). Adherence rate below 90% was associated with increased relapse risk (hazard ratio, 3.1, p=0.04). Using adherence rate <90% to define non-adherence, 46% of African Americans and 28% of Asians as compared with 14% of non-Hispanic whites were non-adherers (p<0.0001). Moreover, 31% of relapses were attributable to non-adherence. We identify race-specific determinants of adherence, and define a clinically-relevant level of adherence needed to minimize relapse risk in a multiracial cohort of children with ALL. This study was registered at ClinicalTrials.gov, identifier: NCT00268528.
- Submitted January 27, 2014.
- Accepted April 30, 2014.
- Copyright © 2014 American Society of Hematology