Validity, sensitivity and specificity of the mentation, behavior and mood subscale of the UPDRS

Objective: The unified Parkinson's disease rating scale (UPDRS) is the most widely used tool to rate the severity and the stage of Parkinson's disease (PD). However, the mentation, behavior and mood (MBM) subscale of the UPDRS has received little investigation regarding its validity and sensitivity. Three items of this subscale were compared to criterion tests to examine validity, sensitivity and specificity. Methods: Ninety- seven patients with idiopathic PD were assessed on the UPDRS. Scores on three items of the MBM subscale, intellectual impairment, thought disorder and depression, were compared to criterion tests, the telephone interview for cognition status (TICS), psychiatric assessment for psychosis and the geriatric depression scale (GDS). Non- parametric tests of association were performed to examine concurrent validity of the MBM items. The sensitivities, specificities and optimal cutoff scores for each MBM item were estimated by receiver operating characteristic (ROC) curve analysis. Results: The MBM items demonstrated low to moderate correlation with the criterion tests, and the sensitivity and specificity were not strong. Even using a score of 1.0 on the items of the MBM demonstrated a sensitivity/specificity of only 0.19/0.48 for intellectual impairment, 0.60/0.72 for thought disorder and 0.61/0.87 for depression. Using a more appropriate cutoff of 2.0 revealed sensitivities of 0.01, 0.38 and 0.13 respectively. Discussion: The MBM subscale items of intellectual impairment, thought disorder and depression are not appropriate for screening or diagnostic purposes. Tools such as the TICS and the GDS should be considered instead.