Original Article| Volume 23, ISSUE 6, P1604-1610, July 2014

Cog-4 Has Limited Diagnostic Test Accuracy and Validity for Cognitive Assessment in Stroke Survivors


      Guidelines recommend cognitive screening for all stroke survivors but do not suggest a preferred tool. Certain elements (orientation, executive function, language, and inattention) of the impairment scale, National Institutes of Health Stroke Scale (NIHSS), have been suggested as a short cognitive screening test—Cog-4. We aimed to describe accuracy and validity of Cog-4 against a more detailed cognitive assessment (Montreal Cognitive Assessment [MoCA]).


      We assessed consecutive acute stroke unit admissions in 2 hospitals over 3 months. Four independent blinded assessors performed NIHSS and MoCA between days 1 and 4 poststroke. We described test properties of Cog-4 for MoCA-defined cognitive impairment using usual thresholds (Cog-4 ≥ 1 and MoCA < 26 of 30) and described the correlations of individual Cog-4 components with broadly equivalent MoCA domains.


      We assessed 173 participants; 166 had Cog-4 data and 148 MoCA. MoCA described 84% (n = 124) of assessed participants as having cognitive impairment and the Cog-4, 37% (n = 62). Cog-4 had a sensitivity of .36 (95% confidence interval [CI]: .28-.45) and a specificity of .96 (95% CI: .80-.99) (positive predictive value: .98, negative predictive value: .23) for MoCA-defined cognitive impairment. Individual Cog-4 items correlated with certain MoCA domains, but the strength of association was modest (r = −.44 orientation, −.37 language, −.19 for inattention, and no significant correlation for executive function, P = .72).


      Our data suggest that many stroke survivors with MoCA-defined cognitive problems would not be detected by Cog-4. Subtest correlations suggest that Cog-4 may not be a valid measure of the cognitive domains that it purports to describe. Other brief cognitive screening tests may be better suited to acute stroke.

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        • Patel M.
        • Coshall C.
        • Rudd A.G.
        • et al.
        Natural history of cognitive impairment after stroke and factors associated with its recovery.
        Clin Rehabil. 2003; 17: 158-166
        • Lawrence E.S.
        • Coshall C.
        • Dundas R.
        • et al.
        Estimates of the prevalence of acute stroke impairments and disability in a multiethnic population.
        Stroke. 2001; 32: 1279-1284
        • Robertson I.H.
        • Ridgeway V.
        • Greenfield E.
        • et al.
        Motor recovery after stroke depends on intact sustained attention: a 2-year follow-up study.
        Neuropsychology. 1997; 11: 290-295
        • Robinson R.G.
        • Bollawilson K.
        • Kaplan E.
        • et al.
        Depression influences intellectual impairment in stroke patients.
        Br J Psychiatry. 1986; 148: 541-547
        • Patel M.D.
        • Coshall C.
        • Rudd A.G.
        • et al.
        Cognitive impairment after stroke: clinical determinants and its associations with long-term stroke outcomes.
        J Am Geriatrics Soc. 2002; 50: 700-706
        • Zinn S.
        • Dudley T.K.
        • Bosworth H.B.
        • et al.
        The effect of poststroke cognitive impairment on rehabilitation process and functional outcome.
        Arch Phys Med Rehabil. 2004; 85: 1084-1090
      1. Scottish Intercollegiate Guidelines Network (SIGN). Management of patients with stroke. Rehabilitation, prevention and management of complications and discharge planning. In: Scottish Intercollegiate Guidelines Network, ed. SIGN Publication Guideline 2010. Edinburgh, UK: Healthcare Improvement Scotland (HIS), 2010.

        • Lees R.
        • Fearon P.
        • Harrison J.K.
        • et al.
        Cognitive and mood assessment in stroke research: focused review of contemporary studies.
        Stroke. 2012; 43: 1678-1680
      2. Lees R, Quinn T, Broomfield N. Questionnaire assessment of usual practice in mood and cognitive assessment in Scottish stroke units. Disability Rehabil.

        • Brott T.
        • Adams Jr., H.P.
        • Olinger C.P.
        • et al.
        Measurements of acute cerebral infarction: a clinical examination scale.
        Stroke. 1989; 20: 864-870
        • Cumming T.B.
        • Blomstrand C.
        • Bernhardt J.
        • et al.
        The NIH stroke scale can establish cognitive function after stroke.
        Cerebrovasc Dis. 2010; 30: 7-14
        • Bour A.
        • Rasquin S.
        • Boreas A.
        • et al.
        How predictive is the MMSE for cognitive performance after stroke?.
        J Neurol. 2010; 257: 630-637
        • Nys G.M.
        • van Zandvoort M.J.
        • de Kort P.L.
        • et al.
        Restrictions of the Mini-Mental State Examination in acute stroke.
        Arch Clin Neuropsychol. 2005; 20: 623-629
        • Ankolekar S.
        • Renton C.
        • Sprigg N.
        • et al.
        The Cog-4 subset of the National Institutes of Health Stroke Scale as a measure of cognition: relationship with baseline factors and functional outcome after stroke using data from the virtual International Stroke Trials Archive.
        Stroke Res Treat. 2013; 2013: 6
        • Hajjar K.
        • Fulton R.L.
        • Diener H.C.
        • et al.
        Does the cognitive measure Cog-4 show improvement among patients treated with thrombolysis after acute stroke?.
        Int J Stroke. 2013; 8: 652-656
        • Gottesman R.F.
        • Kleinman J.T.
        • Davis C.
        • et al.
        The NIHSS-plus: improving cognitive assessment with the NIHSS.
        Behav Neurol. 2010; 22: 11-15
        • Thomas S.A.
        • Lincoln N.B.
        Factors relating to depression after stroke.
        Br J Clin Psychol. 2006; 45: 49-61
        • Laska A.C.
        • Martensson B.
        • Kahan T.
        • et al.
        Recognition of depression in aphasic stroke patients.
        Cerebrovasc Dis. 2007; 24: 74-79
        • Lees R.
        • Corbet S.
        • Johnston C.
        • et al.
        Test accuracy of short screening tests for diagnosis of delirium or cognitive impairment in an acute stroke setting.
        Stroke. 2013; 44: 3078-3083
        • Quaranta D.
        • Marra C.
        • Gainotti G.
        Mood disorders after stroke: diagnostic validation of the poststroke depression rating scale.
        Cerebrovasc Dis. 2008; 26: 237-243
        • Hachinski V.
        • Iadecola C.
        • Petersen R.C.
        • et al.
        National Institute of Neurological Disorders and Stroke-Canadian Stroke Network vascular cognitive impairment harmonization standards.
        Stroke. 2006; 37: 2220-2241
        • Nasreddine Z.S.
        • Phillips N.A.
        • Bedirian V.
        • et al.
        The Montreal Cognitive Assessment, MoCA: a brief screening tool for mild cognitive impairment.
        J Am Geriatr Soc. 2005; 53: 695-699
        • Pendlebury S.T.
        • Mariz J.
        • Bull L.
        • et al.
        MoCA, ACE-R, and MMSE versus the National Institute of Neurological Disorders and Stroke-Canadian Stroke Network Vascular Cognitive Impairment Harmonization Standards Neuropsychological Battery after TIA and stroke.
        Stroke. 2012; 43: 464-469
        • Bossuyt P.M.
        • Reitsma J.B.
        • Bruns D.E.
        • et al.
        Towards complete and accurate reporting of studies of diagnostic accuracy: the STARD initiative.
        Br Med J. 2003; 326: 41-44
        • Whiting P.F.
        • Rutjes A.W.
        • Westwood M.E.
        • et al.
        QUADAS-2: a revised tool for the quality assessment of diagnostic accuracy studies.
        Ann Intern Med. 2011; 155: 529-536
      3. STARDdem Initiative. Available at: Accessed January 2014.

        • Bamford J.
        • Sandercock P.
        • Dennis M.
        • et al.
        Classification and natural history of clinically identifiable subtypes of cerebral infarction.
        Lancet. 1991; 337: 1521-1526
        • Damian A.M.
        • Jacobson S.A.
        • Hentz J.G.
        • et al.
        The Montreal Cognitive Assessment and the mini-mental state examination as screening instruments for cognitive impairment: item analyses and threshold scores.
        Dementia Geriatr Cogn Disord. 2011; 31: 126-131
        • Schuetz G.M.
        • Schlattmann P.
        • Dewey M.
        Use of 3 × 2 tables with an intention to diagnose approach to assess clinical performance of diagnostic tests: meta-analytical evaluation of coronary CT angiography studies.
        Br Med J. 2012; : 345
        • Dong Y.H.
        • Sharma V.K.
        • Chan B.P.L.
        • et al.
        The Montreal Cognitive Assessment (MoCA) is superior to the Mini-Mental State Examination (MMSE) for the detection of vascular cognitive impairment after acute stroke.
        J Neurol Sci. 2010; 299: 15-18
        • Riepe M.W.
        • Riss S.
        • Bittner D.
        • et al.
        Screening for cognitive impairment in patients with acute stroke.
        Dementia Geriatr Cogn Disord. 2004; 17: 49-53
        • Schmidt R.
        • Mechtler L.
        • Kinkel P.R.
        • et al.
        Cognitive impairment after acute supratentorial stroke: a 6-month follow-up clinical and computed tomographic study.
        Eur Arch Psychiatry Clin Neurosci. 1993; 243: 11-15
        • Godefroy O.
        • Fickl A.
        • Roussel M.
        • et al.
        Is the Montreal Cognitive Assessment superior to the Mini-Mental State examination to detect poststroke cognitive impairment? A study with neuropsychological evaluation.
        Stroke. 2011; 42: 1712-1716
        • Hurford R.
        • Charidimou A.
        • Fox Z.
        • et al.
        Domain-specific trends in cognitive impairment after acute ischaemic stroke.
        J Neurol. 2013; 260: 237-241
        • Pendlebury S.T.
        • Wadling S.
        • Silver L.E.
        • et al.
        Transient cognitive impairment in TIA and minor stroke.
        Stroke. 2011; 42: 3116-3121