The Mini Mental State Examination does not accurately screen for objective cognitive impairment in Fabry Disease

Fabry disease (FD) patients may suffer from objective cognitive impairment (OCI). This study assessed the accuracy of the Mini Mental State Examination (MMSE) to screen for OCI in FD patients. Presence or absence of OCI was established using a neuropsychological test battery. For different MMSE cutoffs sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and clinical utility index (CUI) to identify OCI were calculated. Eighty-one patients were included (mean age 44.5 ± 14.3, 35% men, 74% classical phenotype) of which 13 patients (16%) had OCI. The median MMSE score was 29 (range: 25-30). MMSE cutoffs ≤28 and ≤29 had the highest sensitivity and specificity, with higher specificity reached at cutoff ≤28 (sensitivity: .46, specificity: .73) and higher sensitivity at cutoff ≤29 (sensitivity: .92, specificity: .40). PPV was low for both cutoffs (PPV ≤28: .25, PPV ≤29: .23) resulting in a low positive CUI (case finding ability). The results of our study indicate that the MMSE does not accurately screen for OCI in FD, with poor sensitivity-specificity trade-off at all cutoffs. The low PPV shows that the majority of FD patients that score below the cutoffs do not suffer from OCI. Administering the MMSE as a screening test will lead to unnecessary referrals for neuropsychological testing, which is time consuming and burdensome. Screening tools designed to accurately detect mild (executive) impairment might prove more appropriate to screen for OCI in FD.