Evaluation of a Summary Score of Cognitive Performance for Use in Trials in Perioperative and Critical Care

Abstract

Background/Aims: Cognitive dysfunction after medical treatment is increasingly being recognized. Studies on this topic require repeated cognitive testing within a short time. However, with repeated testing, practice effects must be expected. We quantified practice effects in a demographically corrected summary score of a neuropsychological test battery repeatedly administered to healthy elderly volunteers. Methods: The Consortium to Establish a Registry for Alzheimer’s Disease (CERAD) Neuropsychological Assessment Battery (for which a demographically corrected summary score was developed), phonemic fluency tests, and trail-making tests were administered in healthy volunteers aged 65 years or older on days 0, 7, and 90. This battery allows calculation of a demographically adjusted continuous summary score. Results: Significant practice effects were observed in the CERAD total score and in the word list (learning and recall) subtest. Based on these volunteer data, we developed a threshold for diagnosis of postoperative cognitive dysfunction (POCD) with the CERAD total score. Conclusion: Practice effects with repeated administration of neuropsychological tests must be accounted for in the interpretation of such tests. Ignoring practice effects may lead to an underestimation of POCD. The usefulness of the proposed demographically adjusted continuous score for cognitive function will have to be tested prospectively in patients.

Assessing the Discriminant Ability, Reliability, and Comparability of Multiple Short Forms of the Boston Naming Test in an Alzheimer's Disease Center Cohort

“…A number of the participants, including those with MCI and dementia, had been exposed to the CERAD BNT-15 prior to their first administration of the 60-item BNT. It is possible that practice effects elevated the scores on the BNT with repeated longitudinal assessment [27, 32, 33]. All short-form scores were derived via the full version.…”

CERAD practice effects and attrition bias in a dementia prevention trial

“…As a result, practice effects in this battery may have tremendous significance. However, only a few studies have examined practice effects on the CERAD battery (Burkhart et al , 2011; Rosetti et al , 2010; Stein et al , 2012; Zehnder et al , 2007). Although Stein et al (2012) examined practice effects in cognitively normal adults, only the selected subtests of verbal fluency, word list recall, word list memory, and word list recognition were studied.…”

“…Of the previously listed studies examining practice effects on the CERAD, only two investigated the total score (Burkhart et al , 2011; Rosetti et al , 2010) developed by Chandler et al (Chandler et al , 2005) as an indicator of global cognitive status. Rosetti et al (2010) examined 383 normal controls and 655 participants with AD to learn more about progression in AD over time.…”

“…Although the effect of attrition on degree of change over time was evaluated, this study only investigated attrition in the dementia group and did not assess drop-out in normal controls. Additionally, Burkhart et al (2011) examined 57 healthy older adults who were at least 65 years of age using the German version of the CERAD on study entry and then again at seven and 90 day follow-up. Short intervals were used to approximate the typical time intervals utilized in postoperative cognitive dysfunction (POCD) research.…”

“…CERAD total scores increased significantly and were five points higher than baseline on seven day follow-up and seven points higher than baseline on 90 day follow up. Although Rosetti et al (2010) and Burkhart et al (2012) examined practice effects on the CERAD total score, those studies did not follow participants beyond three months (Burkhart et al , 2011), nor did they examine the relative contribution of the individual subtest components (Rosetti et al , 2010), or the effect of participant dropout in normally aging individuals (Burkhart et al , 2011; Rosetti et al , 2010). People experiencing cognitive difficulties may withdraw from study participation which may also serve to skew group performance.…”