Rating dysthymia: an assessment of the construct and content validity of the Cornell Dysthymia Rating Scale

Background: Mason et al. developed the Cornell Dysthymia Rating Scale (CDRS), a 20-item clinician-rated inventory, and hypothesized that it may be superior to the commonly-used Hamilton Depression Rating Scale (HDRS) in assessing the symptoms of dysthymia, a form of chronic depression. The purpose of this study was to compare these instruments in an outpatient sample of dysthymic patients. Method: The CDRS and the HDRS and other inventories (including the Hopkins Symptom Check List (SCL)) were administered to 110 patients meeting DSM-IIIR diagnosis of dysthymia. Results: There was a significant correlation between the CDRS and the HDRS at baseline and termination, indicating concurrent validity. Distributional statistics were compared for baseline and termination severity scores, showing that the CDRS has greater severity range scores than the HDRS. Furthermore, results of the DSM-IV Mood Disorders Field Trial suggest that the CDRS has better content validity than the HDRS when it comes to the dysthymic population. Limitations: The results are limited by the use of a homogeneous sample, the absence of observer ratings of divergent symptoms, and less than excellent validity of self-report divergent symptoms. Conclusions: Our results support the value of the CDRS in assessing symptoms of dysthymia.