Treatment-resistant depression and Axis II comorbidity

Abstract

Background: Researchers of unipolar depression have speculated that personality disturbance is a contributing factor in the development of treatment resistance. The purpose of this study was to compare the prevalence of Axis II disorders between a sample of rigorously defined, treatment-resistant depressed outpatients and a sample of depressed outpatients not having experienced treatment resistance.

Methods: 53 patients with treatment-resistant depression (TRD) and 105 patients with non-treatment-resistant depression (non-TRD) were recruited through respective outpatient clinical trials at the Massachusetts General Hospital's Depression Clinical and Research Program. Diagnosis of Major Depressive Disorder was made using the Structured Clinical Interview for the DSM-III-R, personality disorders were assessed using the Structured Clinical Interview for DSM-III-R Personality Disorders, and antidepressant treatment resistance was defined using the McLean Hospital Antidepressant Treatment Record. Participants from both studies were matched for baseline HAM-D-17 total score and gender. Multiple chi-square analysis was used to compare frequencies of Axis II disorders between TRD and non-TRD patients as well as to compare categorical baseline demographic variables. Unpaired t tests were used to compare baseline demographic and clinical variables measured in a continuous manner.

Results: Non-TRD patients had a higher rate of obsessive-compulsive personality disorder than TRD patients, but this difference was not statistically significant after adjusting for multiple comparisons. No other differences were found to be statistically significant. Range of Axis II comorbidity was 0.0-30.2% for TRD patients and 2.9-37.1% for non-TRD patients.

Conclusions: In this sample, treatment resistance in a current major depressive episode was not associated with an increased rate of Axis II disorders. Strengths of this study include the use of structured interview instruments to assess Axis I and II conditions, and having the two study groups matched for gender and baseline severity of depression. Limitations of this study include a modest sample size and reliance on DSM personality constructs.