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Ann Thorac Surg 2007;84:358-359
© 2007 The Society of Thoracic Surgeons

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Correspondence

Reply

^a Heart Research Centre, Melbourne, Australia
^b Department of Cardiothoracic Surgery, The Royal Melbourne Hospital, Melbourne, Australia

(Email: christine.ernest{at}heartresearchcentre.org).

To the Editor:

The neurocognitive outcomes study [1] was one of two subsidiary studies encompassed by our randomized, controlled clinical trial of on-pump versus off-pump coronary artery bypass surgery (CABGS). The other study examined psychosocial issues including mood states and quality of life before and after CABGS in the same randomized sample. The comments made by Al-Ruzzeh and O’Regan [2] are understandable as the neurocognitive outcome article does not report these mood-related variables. However, in keeping with the recommendations of the consensus statement [3], the randomized patients completed a large battery of mood-related questionnaires at the same time intervals as the neurocognitive assessment, before surgery, as well as 2 and 6 months after surgery. Analyses of this data showed that the on-pump and off-pump groups were not significantly different in regard to levels of pre-surgical anxiety, depression, or quality of life, as would be expected in a properly randomized sample. In addition, pre-surgical anxiety and depression did not significantly predict neurocognitive test scores prior to surgery in our sample, as reported in another of our recently published articles on this study [4]. Therefore, although mood states can influence post-bypass neurocognitive outcomes, it is highly unlikely that the neurocognitive outcome results reported in our article are confounded by these issues. The conclusion of our study is that all other factors being equal, including mood states and quality of life, the on-pump and off-pump procedures do not differentially influence post-surgical neurocognitive outcome.

As Al-Ruzzeh and O’Regan [2] point out, it will be useful to publish the clinical outcomes in the study. We agree. The first of these articles appears in a recent edition of The Annals of Thoracic Surgery [5] and others will be published in due course.

We further agree with Al-Ruzzeh and O’Regan [2] that a level of caution and systematization is important in randomized trials that examine post-surgical neurocognitive outcomes. The data analysis methods used were chosen after much consultation and review of statistical methodology used in other recent studies. Despite the recommendations of the consensus, we believe that the methods we have used provide a clearer picture of the changes in cognition after surgery, particularly because we found that some cognitive test scores changed in a nonlinear fashion, contrary to the assumption inherent in many of the conventional analyses such as analysis of covariance. In addition, as stated by Al-Ruzzeh and O’Regan [2], there are inherent difficulties with the use of change scores and classification of deterioration that can be avoided by the use of structural equation modeling. We hope that our findings will encourage researchers to examine nonlinear models of change, thus creating further discussion about the recommended methods of analyses of this type of data.

	References

Top References

 

1. Ernest C, Worcester M, Tatoulis J, et al. Neurocognitive outcomes in off-pump versus on-pump bypass surgery: a randomized controlled trial Ann Thorac Surg 2006;81:2105-2114.[Abstract/Free Full Text]
2. Al-Ruzzeh S, O’Regan D. Assessment of neurocognitive outcome after cardiac surgery (letter) Ann Thorac Surg 2007;84:358.[Free Full Text]
3. 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]
4. Ernest CS, Elliott PC, Murphy BM, et al. Predictors of cognitive function in candidates for coronary artery bypass graft surgery J Int Neuropsychol Soc 2007;13:257-266.[Medline]
5. Tatoulis J, Rice S, Davis P, Goldblatt JC, Marasco S. Patterns of postoperative systemic vascular resistance in a randomized trial of conventional on-pump versus off-pump coronary artery bypass graft surgery Ann Thorac Surg 2006;82:1436-1444.[Abstract/Free Full Text]

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): James Tatoulis Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Ernest, C. Articles by Goble, A. Search for Related Content PubMed Articles by Ernest, C. Articles by Goble, A. Related Collections Related Article