Treatment patterns in patients with treatment-resistant depression in Danish patients with major depressive disorder.

Objective: To describe treatment patterns in patients with treatment-resistant depression (TRD) and major depressive disorder (MDD) stratified by depression severity and year of diagnosis. Patterns of treatment were also compared to country-specific guidelines.

Methods: All adults registered first time with a hospital contact due to MDD from 1996 through 2015 were identified and followed for all dispensed prescriptions of antidepressants, antipsychotics, lithium, initiation of electroconvulsive therapy (ECT), and psychotherapy in Danish registers 12 months before and after their hospital MDD diagnosis. TRD was characterized by two shifts in treatment.

Results: We identified 197,615 patients of whom 15% developed TRD. In total, 88% of patients started treatment with antidepressants or ECT. Selective serotonin reuptake inhibitors (SSRIs) were the most frequently used treatment during the study period and more than half (50.7%) of patients changed treatment at least once. Among patients with TRD, serotonin and noradrenaline reuptake inhibitors (SNRIs) were the most frequently used treatment (55.9%), and 37.0% initiated a new treatment the following year. SSRIs and SNRIs were part of most combinations of treatment, regardless of depression severity, year of diagnosis, or presence of TRD.

Conclusion: 15% of patients met the criteria for TRD. Irrespective of patient characteristics and year of diagnosis, SSRIs and SNRIs are the most used treatments for depression, even after patients met the criteria for TRD. We confirm that guidelines for first treatment were followed for most patients diagnosed with MDD in Denmark, but for patients with TRD, choice of treatment was arbitrary.