Does comorbid subthreshold anxiety predict treatment response in depression? Results from a naturalistic cohort study (the CRESCEND study).

OBJECTIVE: To investigate whether the anxious depression defined as depression with clinically significant anxiety but not comorbid anxiety disorder predicts poor outcomes of depression treatment in naturalistic clinical setting.

METHOD: From nationwide sample of 18 hospitals, 674 patients with moderate to severe depression who completed the DSM-IV-based Structured Clinical Interview (SCID) were recruited. Anxious depression was defined as not having comorbid anxiety disorder by SCID and having a Hamilton Rating Scale for Anxiety (HAM-A) total score ≥ 20. Participants were classified into three groups: anxious depression (N=259), non-anxious depression (N=351), or comorbid anxiety disorder (N=64). Rates of and time to remission and response and changes in scale scores were compared between these groups during 12 weeks treatment with antidepressant interventions freely determined by clinicians.

RESULTS: No significant differences were observed in the Hamilton Rating Scale for Depression (HAM-D) remission rate and the time to achieve HAM-D remission between anxious and non-anxious depression after adjustment for variables is not equally distributed at baseline. There were also no significant differences in HAM-D and HAM-A response rate and time to responses between two groups. Patients with comorbid anxiety disorder showed less improvement on HAM-D and HAM-A score than did those with anxious depression despite similar baseline symptom severity.

LIMITATION: This study was observational, and the treatment modality was naturalistic.

CONCLUSIONS: Anxious depression did not predict worse outcome to antidepressants treatment. This finding might result from exclusion of comorbid anxiety disorder from anxious depression population and allowance of broad treatment modality.