title: Test accuracy of short screening tests for diagnosis of delirium or cognitive impairment in an acute stroke unit setting.
abstract: OBJECTIVE
  Guidelines recommend cognitive screening in acute stroke. Various instruments are available, with no consensus on a preferred tool. We aimed to describe test accuracy of brief screening tools for diagnosis of cognitive impairment and delirium in acute stroke.
  
  
  METHODS
  We collected data on sequential stroke unit admission in a single center. Four assessors trained in cognitive testing independently performed screening and reference tests. Brief assessments comprised the following: 10- and 4-point Abbreviated Mental Test (AMT-10; AMT-4); 4-A Test (4AT); Clock Drawing Test (CDT); Cog-4; and Glasgow Coma Scale (GCS). We also recorded the multidisciplinary team's informal review using single question (SQ). We compared against reference standards of Montreal Cognitive Assessment (MoCA) and Confusion Assessment Method for delirium using usual diagnostic cutpoints. For MoCA, we described effects of lowering the diagnostic threshold to MoCA <24 and MoCA <20. We described sensitivity, specificity, and positive and negative predictive values.
  
  
  RESULTS
  Over a 10-week period, 111 subjects had cognitive assessment data. Subjects were 50% male (n=55), and median age was 74 years (interquartile range, 64-85). AMT-4, AMT-10, and SQ all had excellent (1.00) specificity for detection of cognitive impairment, although sensitivity was poor (all <0.60). The 4AT had greatest sensitivity for detecting delirium (1.00 [confidence interval [CI], 0.74-1.00]) and reasonable specificity (0.82 [CI, 0.72-0.89]). Properties of 4AT for detection of cognitive impairment, at the traditional MoCA threshold, were also good (sensitivity, 0.86; specificity, 0.78). Using diagnostic thresholds of MoCA ≤26, <24, and <20 gave proportions with cognitive impairments of 86%, 61%, and 49%, respectively, with resulting changes in screening test properties. At lower MoCA thresholds, CDT had favorable sensitivity and specificity (MoCA <20: sensitivity, 0.93, specificity, 0.66; MoCA <24: sensitivity, 0.85, specificity, 0.77).
  
  
  CONCLUSIONS
  Many brief screening assessments are specific but not sensitive for detection of cognitive impairment in acute stroke. Our primary analysis suggests that 4AT is a reasonable choice for delirium and cognitive screening in this setting. However, these data are based on standard MoCA diagnostic threshold and may not be suited for an acute stroke population.
authors.affiliation: From the Institute of Cardiovascular and Medical Sciences (R.L., T.J.Q.) and Undergraduate Medical School (S.C., C.J., E.M., G.S.), College of Medial, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.
authors.forename: Rosalind
authors.initials: R
authors.lastname: Lees
authors.forename: Sinead
authors.initials: S
authors.lastname: Corbet
authors.forename: Christina
authors.initials: C
authors.lastname: Johnston
authors.forename: Emma
authors.initials: E
authors.lastname: Moffitt
authors.forename: Grahame
authors.initials: G
authors.lastname: Shaw
authors.forename: Terence J
authors.initials: TJ
authors.lastname: Quinn
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003072:Cognition Disorders / Q000150:complications* / Q000175:diagnosis*; D003693:Delirium / Q000150:complications* / Q000175:diagnosis*; D005260:Female; D015600:Glasgow Coma Scale; D006757:Hospital Units; D006801:Humans; D008297:Male; D008609:Mental Status Schedule; D008875:Middle Aged; D009483:Neuropsychological Tests; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D020521:Stroke / Q000150:complications / Q000503:physiopathology*; D011795:Surveys and Questionnaires
keywords: cognitive impairment; delirium; measures; outcomes assessment; sensitivity ▪ specificity; stroke