Accuracy of Two Cognitive Screening Tools to Detect Mild Cognitive Impairment in Parkinson's Disease

Abstract

Background Patients with Parkinson's disease (PD) who have mild cognitive impairment (PD‐MCI) are at increased risk of developing PD dementia (PDD). Therefore, it is important to identify PD‐MCI in a reliable way. Objectives We evaluated the accuracy of the Parkinson's Disease‐Cognitive Rating Scale (PD‐CRS) and the Mattis Dementia Rating Scale‐2 (MDRS‐2) for detecting PD‐MCI. Data from healthy subjects were used to correct for demographic influences. Methods We compared the accuracy of the two instruments using ROC analysis. The gold standard was level II diagnosis of PD‐MCI according to consensus criteria of the International Parkinson and Movement Disorder Society. Results Seventy‐five healthy subjects and 125 PD patients were included. Education level, age and sex correlated with the PD‐CRS, but only age correlated with the MDRS‐2. Twenty‐seven percent of the patients had PD‐MCI. Areas under the curve (AUCs) for raw scores of PD‐CRS and MDRS‐2 were 0.83 and 0.81, respectively. At the optimal cut‐off for the PD‐CRS (101/102), sensitivity was 88% and specificity was 64%. For the MDRS‐2 (139/140) sensitivity and specificity were 68% and 79%, respectively. AUCs for demographically corrected scores of PD‐CRS and for age‐corrected scores of MDRS‐2 were 0.80 and 0.78, respectively. At the optimal cut‐off for the PD‐CRS, sensitivity was 79% and specificity was 72%, while for the MDRS‐2 these were 77% and 67%, respectively. Conclusions Both cognitive screening tools are suitable for distinguishing PD‐MCI patients from cognitively intact PD patients. Demographical correction of scores did not improve sensitivity and specificity.

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

“…We assessed the methodological quality of the included studies. We considered the case-control studies [ 29 , 57 , 61 ] to be at high risk of bias, as in diagnostic accuracy studies, the use of a case-control design increases both the sensitivity and specificity of the index test [ 53 ].…”

“…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 ].…”

“…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. In terms of risk of bias, if, for example, a study does not include consecutive patients, more difficult cases could be excluded; this leads to an increased sensitivity and specificity of the index test, with a lower number of false positive or false negative test results [ 53 ].…”

“…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.…”

Apathy as a behavioural marker of cognitive impairment in Parkinson’s disease: a longitudinal analysis

“…To assess cognition, we used a general measure of global cognition, the Minimental State Exam (MMSE, Folstein, [28]), and a PD-specific measure, the Parkinson's Disease Cognitive Rating Scale (PD-CRS, [65]). The PD-CRS is a comprehensive cognitive rating battery specifically designed for PD, that can distinguish PD-MCI from PD with intact cognition [43], with validated cut-off scores for PD-MCI [45]. It comprises nine tasks, representing two sub-domains: (1) frontal subcortical tasks (sustained attention, working memory, alternating and action verbal fluency, clock drawing, immediate and delayed free recall verbal memory); and (2) posterior cortical tasks (confrontation naming and clock copying).…”