The Montreal Cognitive Assessment
Short Cognitive Evaluation in a Large Stroke Trial
Background and Purpose—Cognitive function is often ignored in stroke research trials. The brief Montreal Cognitive Assessment (MoCA) may be sensitive to stroke-related cognitive deficits.
Methods—We evaluated the feasibility of administering the MoCA at 3 months in a large stroke trial (A Very Early Rehabilitation Trial [AVERT]).
Results—Data (blinded to intervention group) are presented for 294 patients with mean age of 70.6 years (SD, 12.8); 220 (75%) completed the MoCA, 54 (18%) had missing data, and 20 (7%) had died. Of those surviving to 3 months, the MoCA was completed by 87% with mild stroke, 79% with moderate stroke, and 67% with severe stroke on admission. Mean MoCA score was 21.1 (SD 7.5) out of 30; only 78 of 220 (35%) patients attained the “normal” cutoff (≥26).
Conclusions—The MoCA is a feasible global cognitive screening tool in stroke trials.
Clinical Trial Registration—URL: www.anzctr.org.au/trial_view.aspx?ID=1266. Unique identifier: ACTRN12606000185561.
Cognitive function is often compromised after stroke,1 yet it is rarely assessed in research trials. Of 190 acute stroke treatment trials, only 3 included specific measures of cognitive outcome.2 Many existing cognitive screening tools were developed for dementia and are weighted toward memory and orientation (eg, the Mini-Mental State Examination).3 The profile of poststroke vascular cognitive impairment differs from the more predictable memory-focused decline of Alzheimer disease, and the Mini-Mental State Examination can lack validity in patients with stroke.4 Recently, the Montreal Cognitive Assessment (MoCA) has been proposed as a screening tool that promises greater sensitivity to deficits arising from stroke and vascular cognitive impairment.5 Early validation studies indicated that the MoCA had >80% sensitivity to detect mild cognitive impairment compared with the Mini-Mental State Examination's sensitivity of <20%.6 Superior sensitivity has also been demonstrated in stroke populations.7,8 In 2008, the MoCA was included as a 3-month outcome in A Very Early Rehabilitation Trial (AVERT), an ongoing multicenter trial of earlier and more frequent mobilization after stroke.9 We hypothesized that administering the MoCA would be feasible and that a majority of patients with stroke would be classified as cognitively impaired (<26 of 30).
AVERT is a prospective randomized controlled trial with concealed allocation and face-to-face blinded outcome assessment (target n=2104). The trial is ongoing, so this article reports whole group data only.
In July 2010, MoCA data and relevant baseline variables were extracted for patients who had undergone their 3-month assessment. Trial inclusion criteria are broad. Patients were included if they were aged 18+ years, satisfied physiological limits (heart rate, blood pressure, oxygen saturation, temperature), and presented within 24 hours of symptom onset of a first or recurrent stroke. Patients with premorbid disability, rapid deterioration, direct admission to intensive care, concurrent progressive neurological disorder (excepting dementia), acute coronary syndrome, severe heart failure, or requiring palliative care were excluded.
Baseline assessment included age, sex, and stroke severity (National Institutes of Health Stroke Scale). The MoCA includes sections on visuospatial/executive, naming, attention, language, abstraction, delayed recall, and orientation. It is scored out of 30 (extra point for <13 years' education) and the recommended “normal” cutoff is ≥26.6
Descriptive statistics and factor analysis were used to report MoCA data.
In the 2 years from MoCA inception, 294 patients underwent 3-month assessment. Mean age was 70.6 years (SD 12.8), 196 (67%) were male, and 250 (85%) had ischemic stroke. Baseline National Institutes of Health Stroke Scale indicated there were 131 (45%) mild strokes (0 to 7), 95 (32%) moderate strokes (8 to 15), and 68 (23%) severe strokes (16+).
Complete MoCA data were available for 220 patients (75%) at 3 months. Twenty patients (7%) had died and 54 patients (18%) had missing data. All MoCA data were missing in 44 patients and reasons included phone interview (18) and aphasia (11). There were incomplete data for 10 patients with reasons including phone interview (1), aphasia (3), and inability to use a pencil (3). Patient characteristics are outlined in the Table.
Of patients surviving to 3 months, the MoCA was completed by 87% with mild stroke, 79% with moderate stroke, and 67% with severe stroke on admission. Early communication problems were not always a barrier to completion. Of patients surviving to 3 months, MoCA was completed by 85% with no aphasia, 78% with mild to moderate aphasia, and 74% with severe aphasia on admission.
In the 220 patients with complete data, mean total MoCA score was 21.1 (SD 7.5) with a range from 0 to 31 (Figure 1). Median score was 23 (interquartile range, 17 to 27). The “normal” cutoff (≥26) was attained by 78 of 220 (35%) patients.
Figure 2 shows data for individual MoCA questions. The MoCA scale had high internal consistency (Cronbach α=0.86) with all items loading onto a single factor that accounted for 46% of the variance.
This study demonstrates that administering the MoCA at 3 months poststroke is feasible. Only 54 of 274 (20%) patients surviving to 3 months had incomplete MoCA data, and in 19 cases, this was due to telephone follow-up. Therefore, 35 of 274 (13%) patients had missing data due to patient factors (including aphasia, refusal, insufficient English). This completion rate, similar to that found in a population-based study,7 is impressive given that trial inclusion criteria were broad: 55% of patients had moderate or severe stroke (National Institutes of Health Stroke Scale >7) and those with hemorrhagic stroke or previous stroke were not excluded. Nevertheless, the important issue of missing data from cognitive measures remains and must be addressed in statistical analysis. Our findings extend earlier studies in milder populations of mixed stroke and transient ischemic attack.7,8 Severe stroke or acute aphasia was often no barrier to the MoCA completion at 3 months poststroke.
A majority of patients with stroke (65%) were classified as cognitively impaired, which matches previous findings, whether the MoCA was used7 or not.1 This high prevalence may reflect the sensitivity of the MoCA, but it is also possible that the recommended “normal” cutoff is too high for the current population. Resolving this question requires comparison of the MoCA against extended neuropsychological testing or better-matched control data.
Performance was poor on items that have large attentional and executive demands, including trail-making, cube copy, and letter fluency. Word recall was also performed poorly, raising the possibility that memory is often a problem poststroke, but the deficit is only detected when the recall task is sufficiently difficult. Orientation in space and time was good, reinforcing suggestions that the Mini-Mental State Examination's focus on orientation (10 of 30 points) is misplaced in stroke populations.4
These preliminary results indicate that the MoCA is feasible and a good candidate for cognitive screening in stroke trials. Its inclusion in AVERT complements existing efficacy outcomes and will help determine whether early mobilization influences cognitive function.
Sources of Funding
Supported by a National Health and Medical Research Council Project grant (38062) and a Chest, Heart & Stroke Scotland research grant.
We thank the stroke survivors who generously participated and to the clinical staff at all AVERT hospital sites, especially the blinded assessors.
- Received March 2, 2011.
- Revision received March 14, 2011.
- Accepted March 15, 2011.
- © 2011 American Heart Association, Inc.
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