There is a lack of knowledge on utilized pharmacotherapies for treatment resistant depression (TRD).

To investigate the courses of treatment of TRD.

All patients aged 16-65 years and diagnosed with depression in Finland during 2004-2016 were included (identified from nationwide registers for inpatient and specialized outpatient care, sick leaves and disability pensions). New antidepressant users were identified with six-month washout period and followed up for two years to observe the possible emergence of TRD, which was defined as initiation of a third treatment after having two failed pharmacological treatments with adequate duration. Pharmacological treatments were analyzed using PRE2DUP-method.

During follow-up, 177,144 persons had their first registered depression (mean age:39.5, 62.5% women). Of them, 10.9% (N=19,322) met TRD criteria. Among the TRD patients, most common first and second lines antidepressants were as follows: SSRIs (44.6%), mirtazapine (19.0%) and SNRIs (16.5%). As the third line of treatment, 44.2% of TRD patients had antidepressant monotherapy, 32.1% a combination of ≥2 antidepressants, 15.8% antipsychotic or mood stabilizer augmentation and an antidepressant, 4.9% both combination of antidepressants and an augmentation with a mood stabilizer or antipsychotic, 2.7% antipsychotic or mood stabilizer monotherapy and 0.3% ECT monotherapy. Of TRD patients, 36.2% (N=6985) progressed to the fourth line of treatment and most common treatments were antidepressant monotherapy (37.5%), antidepressant combinations (30.8%) and augmentation (20.3%).

Although antidepressant combination and augmentation strategies became more frequent, antidepressant monotherapies were still the most common third and fourth lines of depression treatment.

The study was funded by Janssen and SR is an employee of Janssen.