To measure change in patient activation and self-efficacy in individuals with phenylketonuria (PKU) before and after a 6-month phone-based motivational interviewing (MI) intervention and determine the feasibility of implementing dietary counseling for PKU using an MI approach.

Participants ( n = 31) included preadolescents (7–12 years), adolescents (13–17 years), and adults (18–35 years) with early-treated PKU. Participants completed online questionnaires assessing self-reported stage of change (SOC), patient activation, and self-efficacy for PKU self-management behaviors. The intervention included monthly phone-based dietary counseling using MI during which participants set monthly goals.

Patient activation and self-efficacy were significantly different by age group (both p < 0.01) with higher scores in older participants. Self-efficacy significantly increased from baseline to month 6 among adolescents and adults (7.4 ± 1.9 and 8.6 ± 1.3, respectively, p = 0.002). Preadolescents did not have a significant change in self-efficacy ( p = 0.79). There was no increase in patient activation for preadolescents or adolescents/adults ( p = 0.19 and p = 0.24, respectively). Indicators of learning problems were not significantly associated with self-efficacy ( p = 0.33) or patient activation ( p = 0.83).

These results demonstrate the feasibility of implementing phone-based dietary counseling for PKU using MI. This study also supports further investigation of MI as an intervention approach to improving self-efficacy and self-management behaviors in adolescents and adults with PKU.