Validating a Pragmatic Approach to Cognitive Screening in Stroke Prevention Clinics Using the Montreal Cognitive Assessment
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BACKGROUND AND PURPOSE: The Montreal Cognitive Assessment (MoCA) is used commonly to identify cognitive impairment (CI), but there are multiple published cut points for normal and abnormal. We seek to validate a pragmatic approach to screening for moderate-severe CI, by classifying patients into high-, intermediate-, and low-risk categories. METHODS: A total of 390 participants attending an academic Stroke Prevention Clinic completed the MoCA and more detailed neuropsychological testing. Between April 23, 2012 and April 30, 2014, all consecutive new referrals to the regional Stroke Prevention Clinic who were English-speaking, not severely aphasic, and could see and write well enough to complete neuropsychological testing were assessed for inclusion, and consenting patients were enrolled. CI was defined as ≥2 SDs below normal for age and education on at least 2 cognitive subtests. A single cut point for CI was compared with 2 cut points (high sensitivity and high specificity) generated using receiver operator characteristic and area under the curve analyses. The intermediate-risk group contained those scoring between the 2 cut points. RESULTS: Thirty-four percent of participants had a symptomatic or silent stroke, 34% were seen for possible or probable transient ischemic attack, and 32% were diagnosed with other vascular or nonvascular conditions. Using a single cut point, sensitivity and specificity were optimal with MoCA ≤22, (sensitivity=60.4%, specificity=89.9%, area under the curve=0.801, positive predictive value=48.5%, negative predictive value=93.5%, positive likelihood ratio=6, and negative likelihood ratio=0.4). Using 2 cut points, sensitivity was optimal with MoCA ≥28 (sensitivity=96.2%, negative predictive value =97.6%, and negative likelihood ratio=1.27), and specificity was optimal with MoCA ≤22 (specificity=89.9%, positive predictive value=48.5%, and positive likelihood ratio=6). CONCLUSIONS: Stratifying participants into 3 categories facilitates the identification of a homogenous group at low risk for CI, as well as 2 other groups with intermediate and higher risk. This approach could facilitate clinical care pathways and patient selection for research.
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