The economic impact of depression: resistance or severity?

Treatment-Resistant Depression (TRD) affects 60 to 70% of patients with Major Depressive Disorder (MDD). The economic impact of depression in general, and of TRD specifically, was found to be relatively high. As the course of depression can be defined both by the severity of the disease and by the resistance to treatment, the question of the unique contribution of MDD severity vs. resistance to the economic burden of depression is being raised. One hundred and seven unipolar MDD patients, all treated for at least 4weeks, were enrolled in the study. Patients were assessed for their current MDD severity using the Hamilton Depression Rating Scale (HDRS) and past treatments, and for medical-related costs (number of blood and imaging tests, visits paid to physicians, psychiatric hospitalizations) and incapacity-related costs (number of working days lost) during the last episode. TRD and non-TRD patients were, respectively, 39.3% and 60.7% of the patients recruited for the study. TRD patients had more severe depression, and higher costs for imaging tests, physician visits, psychiatric hospitalizations, and number of working days lost. In addition, higher MDD severity was found to be associated with higher costs. Finally, when controlling for the shared variance of TRD and MDD severity, by using residual scores, TRD was associated with higher costs, but MDD severity was no longer related to costs. While both resistance and severity are associated with higher direct and indirect costs, our findings suggest that TRD may be the main factor in determining the economic burden of depression.