title: The influence of different error estimates in the detection of post-operative cognitive dysfunction using reliable change indices with correction for practice effects.
abstract: The reliable change index (RCI) expresses change relative to its associated error, and is useful in the identification of post-operative cognitive dysfunction (POCD). This paper examines four common RCIs that each account for error in different ways. Three rules incorporate a constant correction for practice effects and are contrasted with the standard RCI that had no correction for practice. These rules are applied to 160 patients undergoing coronary artery bypass graft (CABG) surgery who completed neuropsychological assessments preoperatively and 1 week post-operatively using error and reliability data from a comparable healthy non-surgical control group. The rules all identify POCD in a similar proportion of patients, but the use of the within subject standard deviation, expressing the effects of random error, as an error estimate is a theoretically appropriate denominator when a constant error correction, removing the effects of systematic error, is deducted from the numerator in a RCI.
authors.affiliation: Centre for Anaesthesia and Cognitive Function, Department of Anaesthesia, St. Vincent's Hospital, Victoria Parade, Melbourne 3065, Australia. matt.lewis2@gmail.com
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Lewis
authors.forename: Paul
authors.initials: P
authors.lastname: Maruff
authors.forename: Brendan S
authors.initials: BS
authors.lastname: Silbert
authors.forename: Lis A
authors.initials: LA
authors.lastname: Evered
authors.forename: David A
authors.initials: DA
authors.lastname: Scott
mesh_terms: D000368:Aged; D003072:Cognition Disorders / Q000209:etiology / Q000503:physiopathology*; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data*; D010043:Outcome and Process Assessment, Health Care / Q000706:statistics & numerical data*; D011214:Practice, Psychological; D012680:Sensitivity and Specificity