Electronically Monitored Antidepressant Adherence in Adolescents with Anxiety Disorders: A Pilot Study

Background: Antidepressant medication adherence patterns are inconsistent in adolescents with anxiety and related disorders, and the clinical and demographic features predicting adherence are poorly understood. Methods: In an ongoing single-site prospective trial involving adolescents (aged 12-17) with the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition anxiety disorders treated with escitalopram, adherence was measured for 12 weeks using electronic monitoring caps. Adherence patterns were examined using qualitative and unsupervised clustering approaches, and predictors of adherence were evaluated using logistic regression, with demographic (age, sex, and race) and clinical variables (e.g., anxiety severity [Pediatric Anxiety Rating Scale], irritability [Affective Reactivity Index], depressive symptoms [Children's Depression Rating Scale]). Results: Among adolescents (N = 33) aged 14.5 ± 1.8 years (64% female), four adherence patterns were identified: persistent adherence, intermittent adherence, early adherence-late nonadherence, and nonadherence. In a logistic model of a 5-day moving average measure of adherence, social anxiety disorder (β = -0.68 ± 0.19, p = 0.002) and separation anxiety disorder (β = -0.61 ± 0.18, p < 0.001) were associated with lower adherence. In contrast, panic disorder, attention-deficit/hyperactivity disorder, generalized anxiety disorder, and depressive symptoms were not associated with adherence. Baseline anxiety severity was linked to lower adherence (β = -0.199 ± 0.05, p < 0.001). Older age also reduced adherence (β = -0.342 ± 0.05, p < 0.001), with each additional year of age increasing time spent nonadherent by 5% (p < 0.001). Being female (β = 0.451 ± 0.17, p = 0.011) and expecting treatment to be efficacious (β = 0.092 ± 0.04, p = 0.011) increased adherence, while greater irritability was associated with nonadherence (β = -0.075 ± 0.03, p = 0.006). Conclusions: Antidepressant adherence is variable, with distinct patterns, and those with social and separation anxiety disorders were less likely to be adherent. Factors such as older age, severe anxiety, and greater irritability predicted lower adherence, while being female and expecting treatment efficacy were associated with better adherence. Interventions that address specific symptoms or enhance treatment expectations may improve adherence.