Chapter 4 100 growing number of patients seen each year and because it is likely that the performance of the MoCA is different across settings. Besides, a lot of the former studies were carried out with healthy controls as comparisons causing spectrum-bias. As would be expected, the mean MoCA scores differed significantly between patients with MD, MCI and SNoCI. However within all three groups, the range was substantial – particularly within the MCI group –, making it difficult to differentiate between the three groups using an individual MoCA score as some scores overlap into the other groups. As can be seen in the boxplot (figure 2b), the range has not merely a psychiatric cause as the MCI neurodegenerative group (MCI-ND) have an even wider range. The mean scores of the MD and MCI groups were comparable to those reported in the literature and demonstrate that our results have external validity (Mocatest.Org). Our control group scores were lower than those in the original and most other validation studies that used healthy controls, but we showed in an earlier study that the use of healthy individuals as controls resulted in a high mean MoCA score, leading to an unrealistically good specificity and PPV (Dautzenberg et al., 2020; Noel-Storr et al., 2014). Our mean MoCA scores were very similar to all patient groups referred to a memory clinic, this included the comparison group (Larner, 2012). Another explanation for the lower scores of our comparison group, and hence a lower specificity, is the psychiatric “comorbidity” which is known to decrease the MoCA score on its own (Blair et al., 2016; Ramírez et al., 2014; Wu et al., 2017). Our “low” SNoCI specificity of 47% concurred with another memory clinic study, where the comparison group consisted of referred subjects with memory loss complaints including psychiatric illnesses (Smith et al., 2007). Testing the MoCA in our memory clinic setting revealed a good (Fischer et al., 2003) AUC (0.83) when differentiating between demented and non-demented, but with mediocre specificity (65%). This implies that the MoCA could accurately find most demented patients in a group suspected of CI (sensitivity 90%, <21), but a substantial amount of non-demented patients also scored below this cutoff (of whom 79% are MCI), making it unsuitable for diagnostic purposes but good as a screening tool for MD. This is also demonstrated in the poor PPV of 50 at a cutoff <21. When wishing to use the MoCA to identify those in need of further cognitive workup (triage), a high NPV is needed to safely exclude patients who do not need further diagnostic work-up.
RkJQdWJsaXNoZXIy MTk4NDMw