OBJECTIVES: Treatment-Resistant Depression (TRD) is a condition in which patients with Major Depressive Disorder fail to respond to two or more treatments of adequate dose and duration within an episode. Psychiatrist providers may consider the use of augmentation therapies, the addition of drugs that are not antidepressants, to improve clinical response. The aim of this study was to identify factors associated with augmentation agent use (AU) in this population.

METHODS: Patients with TRD who were treated with a pharmacologic therapy were identified in a cross-sectional survey of healthcare providers in France, Germany, and the UK. Patients were stratified by AU and no AU (NAU) in their first failed, second failed, and current/most recent treatment in their TRD episode. A logistic regression model was developed to assess demographic characteristics, provider, comorbid conditions, and depression characteristics associated with AU.

RESULTS: Comorbidities associated with AU were family history of depression (OR: 1.46 [1.07, 2.01]), borderline personality disorder (BPD) (OR: 1.88 [1.13, 3.14]), substance abuse (OR: 2.37 [1.30, 4.32]), and hypothyroidism (OR: 2.30 [1.16, 4.57]). Patients in France or Germany were less likely to have AU compared to patients in the UK (France Odds Ratio (OR): 0.28 [95% confidence interval: 0.18, 0.46]; Germany OR: 0.45 [0.27, 0.73]). AU was higher among patients with providers who practiced in both the hospital and office settings compared to in the hospital setting only (OR: 2.28 [1.23, 4.23]).

CONCLUSIONS: This study identified family history of depression, BPD, substance abuse, and hypothyroidism to be associated with AU in patients with TRD. Providers in France and Germany are less likely to prescribe augmentation agents compared to in the UK, which may reflect differences in treatment guidelines and attitudes towards AU as treatment for TRD across countries.