Validation of Revised Chinese Version of PD-CRS in Parkinson’s Disease Patients

Abstract

There is a high prevalence of mild cognitive impairment (MCI) and dementia in Parkinson’s disease (PD) patients, but a Chinese version of cognitive rating scale that is specific and sensitive to PD patients is still lacking. The aims of this study are to test the reliability and validity of a Chinese version of Parkinson’s disease-cognitive rating scale (PD-CRS), establish cutoff scores for diagnosis of Parkinson’s disease dementia (PDD) and PD with mild cognitive impairment (PD-MCI), explore cognitive profiles of PD-MCI and PDD, and find cognitive deficits suggesting a transition from PD-MCI to PDD. PD-CRS was revised based on the culture background of Chinese people. Ninety-two PD patients were recruited in three PD centers and were classified into PD with normal cognitive function (PD-NC), PD-MCI, and PDD subgroups according to the cognitive rating scale (CDR). Those PD patients underwent PD-CRS blind assessment by a separate neurologist. The PD-CRS showed a high internal consistency (Cronbach’s Alpha = 0.840). Intraclass Correlation coefficient (ICC) of test-retest reliability reached 0.906 (95% CI 0.860–0.935, p<0.001). ICC of inter-rater reliability was 0.899 (95% CI 0.848–0.933, p<0.001). PD-CRS had fair concurrent validity with MDRS (ICC = 0.731, 95% CI 0.602–0.816). All the frontal-subcortical items showed significant decrease in PD-MCI compared with the PD-NC group (p≤0.001), but the instrument cortical items did not (confrontation naming p=0.717, copying a clock p=0.620). All the frontal-subcortical and instrumental-cortical functions showed significant decline in PDD compared with the PD-NC group (p≤0.001). The cutoff value for diagnosis of PD-MCI is 80.5 with the sensitivity of 75.7% and the specificity of 75.0%, and for diagnosis of PDD is 73.5 with the sensitivity of 89.2% and the specificity of 98.9%. Revised Chinese version of PD-CRS is a reliable, acceptable, valid, and useful neuropsychological battery for assessing cognition in PD patients.

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

“…The use of other sampling methods may lead to a high risk of introducing bias into the study [ 53 ]. 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 ].…”

“…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 ].…”

“…Both types of bias have been shown to increase the sensitivity of a test; however, no systematic effect on specificity has been observed [ 63 ]. Nonetheless, one paper reported that the PD-CRS test and the reference standard were undertaken in a specific order [ 62 ]; hence, the first test (PD-CRS) must have been interpreted blind to the results of the second (CDR). All the other studies were considered to present an unclear risk of bias [ 56 , 60 , 61 ].…”

“…The cognitive tests were administered by a neuropsychologist in most studies [ 29 , 56 , 57 , 58 , 60 ] and by a neurologist in one study [ 62 ].…”

“…In the selected studies, the Cronbach’s alpha of PD-CRS was reported to range from 0.82 to 0.85. For detecting PD-D, although the initial validation study recommended the use of a threshold of ≤ 64 [ 29 ], other studies found that the optimal cut-off was ≤ 62 [ 59 ] or ≤ 73.5 [ 62 ]. When used to detect PD-MCI, cut-offs of ≤ 81 [ 57 , 58 ], 80.5 [ 62 ], or ≤ 101 [ 61 ] have been reported to be useful for optimal screening.…”