Predicting Medication Nonadherence in Older Adults With Difficult-to-Treat Depression in the IRL-GRey Randomized Controlled Trial

Objective: Nonadherence to antidepressants interferes with optimal treatment of late-life depression. This analysis examines clinical and treatment factors predicting medication nonadherence in difficult-to-treat late-life depression. Methods: Secondary analysis of data from a clinical trial of antidepressant pharmacotherapy for Major Depressive Disorder in 468 adults aged 60+ years. All participants received venlafaxine XR for 12 weeks. Nonremitters were randomized to augmentation with either aripiprazole or placebo for 12 additional weeks. Medication adherence was assessed 14 times over 24 weeks. The analyses examined sociodemographic, clinical, and treatment factors that may predict antidepressant nonadherence during early (weeks 1–6), late (weeks 7–12), and augmentation (weeks 13-–24) treatment. Results: Poor cognitive function and early response were predictive of early nonadherence. Poor cognitive function and prior nonadherence were predictive of late nonadherence. Living alone was associated with nonadherence both late and during augmentation treatment. Conclusion: Future studies should consider the role of early response and cognitive function to improve antidepressant adherence, particularly among older adults who live alone.