Metric properties of the mini‐mental Parkinson and SCOPA‐COG scales for rating cognitive deterioration in Parkinson's disease

Abstract

The SCOPA-COG has some advantages over the MMP, the most important being a greater discriminative ability. Multilevel hierarchical analysis clarified the necessity of stratifying the PD population according to educational background, years of illness, and H&Y stage when using these scales.

Psychometric properties of the Italian version of the Scales for Outcomes in Parkinson�s disease-in Parkinson�s disease- Cognition (SCOPA-Cog)

“…In agreement with previous literature (Carod-Artal et al, 2008;Marinus et al, 2003;Serrano-Duenas et al, 2010;Verbaan et al, 2007), we showed that the SCOPA-Cog was able to accurately represent the heterogeneous composition of our neurologically and cognitively mixed study population. Indeed, the scores obtained by our patients covered almost the entire score range of the scale, the distribution was virtually symmetric, the average score overlapped with the median, and there was no ceiling or floor effect.…”

“…In the present study we also confirmed previous evidence about the goodness of the instrument's structure (Carod-Artal et al, 2008;Marinus et al, 2003;Serrano-Duenas et al, 2010), as all the subtests appeared to be tapping the same general cognitive construct, each one being necessary for the consistency of the scale. Precision analysis yielded less satisfying results, indicating that the difference between true cognitive level and observed SCOPA-Cog scores may be relatively large.…”

“…verbal fluency and alternate movements. Finally, our results replicated previous positive findings about the validity of the SCOPA-Cog (Carod-Artal et al, 2008;Marinus et al, 2003;Serrano-Duenas et al, 2010;Verbaan et al, 2007). First of all, the test seemed to be measuring the same construct as the DRS, which can be considered a gold standard for neuropsychological assessment in extrapyramidal diseases (Kulisevsky et al, 2009), and it was able to distinguish patients grouped by their performance on the DRS.…”

“…Precision analysis yielded less satisfying results, indicating that the difference between true cognitive level and observed SCOPA-Cog scores may be relatively large. Similarly high SEM values were also found in previous series (Carod-Artal et al, 2008;Serrano-Duenas et al, 2010), and call for caution before interpreting intra-individual fluctuations of SCOPA-Cog scores as clinically relevant. In line with the findings of previous investigations (Carod-Artal et al, 2008;Marinus et al, 2003), we found an (expected) significant relationship between the test and age and education.…”

“…Its diagnostic performance in PD-associated mild cognitive impairment (MCI) was, instead, less satisfactory, due to low specificity and positive predictive values. Extensive and rigorous evaluation of the psychometric attributes of the original scale has been performed in var-ious studies, yielding generally satisfactory results with regard to score distribution, internal consistency, reliability and validity (Forjaz et al, 2010;Marinus et al, 2003;Serrano-Duenas et al, 2010;Verbaan et al, 2007). In the present multicenter study we evaluated the clinimetric properties of the Italian version of the SCOPA-Cog in a large population of idiopathic PD patients with and without cognitive impairment.…”