Ann Thorac Surg 2008;85:362. doi:10.1016/j.athoracsur.2007.07.078
© 2008 The Society of Thoracic Surgeons
Correspondence
Selection of Neurocognitive Tests and Outcomes of Cardiac Surgery Trials
Anna G. Polunina, MD, PhD
Bakulev Scientific Center of Cardiovascular Surgery, Leninsky pr-t 156-368, Moscow 119571, Russia
(Email: anpolunina{at}mail.ru).
To the Editor:
Selection of neurocognitive tests in cardiac surgery trials is typically based on the Statement of Consensus [1]. Recommended core neuropsychological battery includes the Rey Auditory Verbal Learning Test (RAVLT), the Pegboard Test (PegB), and the Trail Making Test (TMT). At the same time, a series of studies showed that word list learning and psychomotor speed tests were less sensitive to microemboli effects on the brain in comparison with digit learning, visual learning, and design construction [2–4]. We hypothesized that results of cardiac surgery trials may be affected by the choice of neurocognitive tests. To test this hypothesis, we conducted a statistical analysis of 24 publications that reported 34 patient groups (SPSS file is available from the author). The incidence of postoperative cognitive dysfunction (POCD) in 1 to 3 months after on-pump coronary artery bypass surgery was included as an outcome measure. We found that studies that used a word list learning test (eg, the RAVLT) reported lower incidence of POCD in comparison with studies that did not use the RAVLT (mean incidence, 32.8 ± 21.0% vs 47.7 ± 25.1% of patients with POCD; t = 1.81; p = 0.08). Studies that administered a digit learning test (Digit Span) reported significantly higher POCD incidence in comparison with studies that did not use a digit span (mean incidence, 45.7 ± 23.3% vs 26.2 ± 18.0% of patients with POCD; t = 2.63; p = 0.013). Studies that used both word list learning and digit span tests showed the same incidence as studies that used only a digit span test (p = 0.68). Studies that administered nonverbal memory tests also showed significantly higher POCD incidence in comparison with other studies (52.3 ± 20.3 vs 29.7 ± 20.8; t = 3.05; p = 0.005). At the same time, the TMT was associated with significantly lower POCD incidence in comparison with studies that did not use this test (28.0 ± 18.1% vs 45.3 ± 34.2%; t = 2.30; p < 0.05) with the same trend for the PegB (p = 0.10). These data evidence that results of cardiac surgery trials may be considerably influenced by selection of neuropsychological tools. The sensitivity of neurocognitive tests to the effects of intraoperative brain ischemia needs further research.
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References
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- Murkin JM, Newman SP, Stump DA, Blumenthal JA. Statement of consensus on assessment of neurobehavioral outcomes after cardiac surgery Ann Thorac Surg 1995;59:1289-1295.[Free Full Text]
- Bokeriia LA, Golukhova EZ, Breskina NY, et al. Asymmetric cerebral embolic load and postoperative cognitive dysfunction in cardiac surgery Cerebrovasc Dis 2007;23:50-56.[Medline]
- Borger MA, Peniston CM, Weisel RD, Vasiliou M, Green REA, Feindel CM. Neuropsychologic impairment after coronary bypass surgery: effect of gaseous microemboli during perfusionist interventions J Thorac Cardiovasc Surg 2001;121:743-749.[Abstract/Free Full Text]
- Fearn SJ, Pole R, Wesnes K, Faragher EB, Hooper TL, McCollum CN. Cerebral injury during cardiopulmonary bypass: emboli impair memory J Thorac Cardiovasc Surg 2001;121:1150-1160.[Abstract/Free Full Text]
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