Treatment-resistant depression in primary care across Canada.

Objective: Treatment-resistant depression (TRD) represents a considerable global health concern. The goal of the InSight study was to investigate the prevalence of TRD and to evaluate its clinical characterization and management, compared with nonresistant depression, in primary care centres.

Methods: Physicians completed a case report on a consecutive series of patients with major depressive disorder (n = 1212), which captured patient demographics and comorbidity, as well as current and past medication.

Results: Using failure to respond to at least 2 antidepressants (ADs) from different classes as the definition of TRD, the overall prevalence was 21.7%. There were no differences in prevalence between men and women or among ethnicities. Patients with TRD had longer episode duration, were more likely to receive polypharmacy (for example, psychotropic, lipid-lowering, and antiinflammatory agents), and reported more AD related side effects. Higher rates of disability and comorbidity (axes I to III) were associated with treatment resistance. Obesity and being overweight were also associated with treatment resistance. While the selection and sequencing of pharmacotherapy by family physicians in this sample was in line with recommendations from evidence-based treatment guidelines, the wait time to make a change in treatment was 6 to 8 weeks in both groups, which exceeds guideline recommendations.

Conclusions: These real-world data demonstrate the high prevalence of TRD in primary care settings, and underscore the substantial burden of illness associated with TRD.