Abstract
BACKGROUND: Little is known about the continuity of antidepressant treatment after adolescent and young adult (AYA) cancer diagnosis. Clinical guidelines recommend that past antidepressant use trajectories should inform decisions on discontinuation after cancer diagnosis. We characterized AYAs' antidepressant adherence trajectories before incident cancer diagnosis and assessed any association between their past adherence trajectory and the risk of antidepressant discontinuation up to 1 year afterward. METHODS: We conducted a retrospective, longitudinal cohort study of AYAs receiving ≥ 2 antidepressant fills 9 months before incident cancer diagnosis (index date). Group-based trajectory modeling was used to estimate latent subgroups of antidepressant adherence before cancer diagnosis, using monthly proportions of days covered (PDC) over the nine-month baseline; IQVIA PharMetrics Plus for Academics US claims, 2006-2020. Discontinuation was defined as ≥ 60-days gap without antidepressants within 1 year post-index date. RESULTS: We observed three distinct antidepressant adherence trajectory groups before cancer diagnosis: recent start (17% of cohort, mean PDC [range]: 0.25 [0.03-0.49]); gradually increasing (36%, mean PDC [range]: 0.57 [0.22-0.81]); and consistently high (47%, mean PDC [range]: 0.90 [0.62-1.00]). Compared with AYAs exhibiting prior consistently high adherence trajectories, those with recent start (HR, [95% CI] 1.96, [1.46-2.63]) and gradually increasing (HR, [95% CI] 1.52, [1.20-1.93]) trajectories experienced about 2 times the higher risk of antidepressant discontinuation over the year following cancer diagnosis. CONCLUSION: Past antidepressant trajectory is associated with antidepressant discontinuation after AYA cancer diagnosis. Attention is needed in the psycho-oncologic care of AYAs who recently started antidepressants before cancer diagnosis.