Objective: The concurrent validity of this 6-item version of Hamilton Depression Rating Scale (HDRS-6) compared to the original 21-item tool (HDRS-21), using the DSM-IV criteria for major depression as the gold standard in patients with Parkinson's disease.
Methods: In analytical study were analyzed: Cronbach's alpha (alpha C), item-total correlation, the receiver operating characteristic curve (ROC) and their area under the curve (AUC), Finally, used the Fagan nomogram.
Results: The 115-patient sample with mean illness duration of 7.15 years. HDRS-21 achieved an alpha C of 0.83, HDRS-6 a value of 0.68. Eleven of the HDRS-21 items failed to reach a minimum value. HDRS-21 obtained its better AUC capacity of 0.94 (cut/score of 18/19); HDRS-6 got an AUC of 0.92 (cut/score of 7/8). The Fagan nomogram was (89-94% and 83-90%, respectively).
Conclusions: Our results suggest that HDRS-6 is sufficient, valid and has a sound psychometric structure for use with Parkinson's disease patients.