Validation of the Parkinson's Disease‐Cognitive Rating Scale Applying the Movement Disorder Society Task Force Criteria for Dementia Associated with Parkinson's Disease

Abstract

Background: The authors studied the measurement properties of the Parkinson's DiseaseCognitive Rating Scale (PD-CRS) compared with Movement Disorders Society Task Force (MDS-TF) criteria for the diagnosis of dementia in patients with Parkinson's disease. Methods: The sample consisted of 223 patients who were diagnosed in accordance with the United Kingdom Parkinson's Disease Society Brain Bank who were assessed with both the MDS-TF and the PD-CRS criteria (in addition to other instruments) without the assessors' knowledge of previous results. Internal consistency was studied (homogeneity of the items and Guttmann's k values were obtained) in addition to convergent, divergent, and discriminative validity. The receiver operating characteristic curve was obtained, and the cutoff point at which the PD-CRS had the greatest efficiency was analyzed. Results: The internal consistency was shown to be adequate, with a k value of 0.821. A floor effect was observed in 4 of the items (Sustained Attention, Working Memory, Immediate Verbal Memory, and Alternating Verbal Fluency), and 1 item showed a ceiling effect (Clock Copying). The scale adequately discriminated patients with and without dementia (Kruskal-Wallis; P ≤ 0.000). The area under the curve was 0.899. With a cutoff score of 62 (from a possible score of 134), the scale achieved 94% sensitivity and 99% specificity. Conclusions: The PD-CRS has adequate measurement properties and is a valid tool for studying the presence of dementia in patients with Parkinson's disease.Parkinson's disease (PD) is a degenerative disorder of the central nervous system that causes motor and nonmotor symptomatology; the latter includes cognitive deterioration and dementia in up to 40% of cases. Both PD and associated dementia are independent predictors of an elevated risk of mortality in older adults. 1,2The Parkinson's Disease Cognitive Rating Scale (PD-CRS) 3 is a scale used to evaluate cognitive deterioration in patients with PD. Its original validation study demonstrated a sensitivity and specificity of 94% and good internal consistency (Cronbach's a = 0.85). It has been externally validated by investigators other than its authors, demonstrating adequate measurement properties 4,5 ; and, recently, 6 it was stated that the PD-CRS is 1 of the tools designed for evaluating cognitive disorder in patients with PD.The Movement Disorders Society Task Force (MDS-TF), has established diagnostic criteria for dementia in PD 7 and has developed a method for using this tool. 8 The objective of this

Global scales for cognitive screening in Parkinson's disease: Critique and recommendations

“…The scale has been shown to be sensitive to change, with a decrease from 10 to 13 points in the total score indicative of a clinically significant change . A cutoff score of ≤81 points yielded a sensitivity of 79% and specificity of 80% for PD‐MCI compared with healthy controls, and cutoffs of both ≤62 and ≤64 points have sensitivity and specificity of ≥94% for PD‐D compared with healthy controls …”

“…Normative values are available for the Italian version of the PD‐CRS . Administration time is about 20 minutes . The scale is in the public domain, and it can be obtained at http://www.movementscales.com along with training.…”

Parkinson’s Disease-Cognitive Rating Scale for Evaluating Cognitive Impairment in Parkinson’s Disease: A Systematic Review

“…Most of the studies did not report the method used to sample patients for inclusion [ 29 , 57 , 58 , 60 , 61 , 62 ]. A consecutive sample of PD patients was recruited in two studies [ 56 , 59 ]. Furthermore, three studies included only non-demented patients [ 58 , 60 , 61 ], and, therefore, the data obtained cannot be generalized.…”

“…The time period between the administration of PD-CRS and the reference standard was adequate in most studies [ 29 , 56 , 57 , 58 , 60 , 62 ], with a low risk of bias. Only two studies did not report the exact interval between tests [ 59 , 61 ]. Ideally, the index test and the reference standard were performed during the same study visit or in a short time interval.…”

“…Four studies provided data on the “blinding” of the assessors, clearly reporting that it was a blind review [ 29 , 57 , 58 , 59 ]. Interpretation of the results of the PD-CRS may be affected by knowledge of the results of the reference standard (test review bias) and vice versa (diagnostic review bias).…”