Abstract
12131 Background: Adjuvant endocrine therapy (AET) reduces risk of breast cancer (BC) recurrence; however, adherence is suboptimal and interventions are needed. We conducted a randomized controlled trial of a novel telehealth intervention (STRIDE), which led to improvements in symptom distress, coping, quality of life, and mood. Here we examine which patients had improved adherence following STRIDE by exploring characteristics that may moderate intervention effects. Methods: Women (n = 100) with nonmetastatic BC who reported AET-related distress were randomized to receive STRIDE or a medication monitoring control (MM) between 10/2019-6/2021. STRIDE consisted of six weekly, small-group cognitive behavioral telehealth sessions to enhance symptom management and adherence. All patients stored their AET in electronic MEMS Caps bottles to measure objective adherence. We collected patient characteristics (i.e., months on AET, education) and self-report measures at baseline. Patients completed the Medication Adherence Report Scale (MARS-5) and Cancer Therapy Satisfaction Questionnaire to report adherence behaviors (e.g., “I alter the dose”) and AET perceptions (e.g., convenience, expectations, satisfaction), respectively. We conducted hierarchical linear modeling to test moderators of intervention effects on adherence rates (MEMS Caps) across months 1-3, controlling for ovarian suppression receipt and baseline distress due to group differences/stratification. We report the ‘time X group X moderator’ effects here. Results: Among participants reporting greater difficulty (lower MARS-5) with their AET regimen at baseline, STRIDE participants had greater improvement in adherence over time compared to MM participants ( b= -13.80, SE = 4.56, p < .01). Greater expectations of therapeutic benefit predicted improvements in adherence for STRIDE versus MM participants ( b= 0.25 SE = 0.10, p = .01). Additionally, among participants who reported greater convenience of taking AET ( b= 0.33 SE = 0.17, p = .06), had lower education levels ( b= -4.02, SE = 2.12, p = .06), and had been taking AET for fewer months ( b= -0.43 SE = 0.25, p = .09), STRIDE participants showed adherence increases that approached significance. Other moderators were not significant. Conclusions: STRIDE demonstrated effects of a behavioral intervention on AET adherence. Participants reporting greater difficulty adhering to their AET regimen and who expected more benefit showed improved adherence following STRIDE. Gains in adherence from STRIDE were also more pronounced among those who reported that AET was convenient, started the medication more recently, and had lower levels of education. Patient-level and socioeconomic factors influence response to AET adherence interventions. Clinicians may play a key role in addressing modifiable targets at AET initiation (e.g., logistical barriers, perceived benefit) to enhance adherence. Clinical trial information: NCT03837496 .