Adherence to 6-Mercaptopurine (6-MP) and Habit Strength in Pediatric Acute Lymphoblastic Leukemia (ALL).

Background: Low 6-mercaptopurine (6-MP) adherence (< 95%) is associated with increased relapse in pediatric acute lymphoblastic leukemia (ALL). Stronger habit has been associated with higher adherence. We examined the relationship of 6-MP adherence to habit strength and health-related quality of life in pediatric ALL.

Methods: A single-center, cross-sectional study of 52 participants: 11 patients (mean age 16 ± 4) and 41 parents/caregivers (age 37 ± 5). Participants completed Visual Analogue Scale (VAS), Patient Reported Outcomes Measurement Information System Medication Adherence Scale, and the Self-Regulated Habit Index (SRHI). Twelve semi-structured participant interviews were analyzed using thematic analysis.

Results: 81% (42/52) of participants reported high 6-MP adherence (VAS ≥ 95%): patients 91% (10/11), parents 78% (32/41). No significant correlation was found between adherence and habit strength. Reported adherence facilitators included reminders, care team communications, personalized tools, administration experience, self-efficacy, and social support. Conversely, financial burden, scheduling conflicts, and medication access were cited as barriers.

Conclusions: One-fifth of participants reported low 6-MP adherence, with habit strength not associated with adherence. Variability of 6-MP routines may prohibit automaticity. While 6-MP adherence may not correlate with habit strength, interventions promoting and strengthening habit formation may overcome barriers to 6-MP adherence and improve outcomes.