Correspondence  |   May 2003
Postoperative Cognitive Dysfunction: Overinterpretation of Data?: In Reply:—
Author Notes
  • Hope Hospital, Salford, United Kingdom. tim.
Article Information
Correspondence   |   May 2003
Postoperative Cognitive Dysfunction: Overinterpretation of Data?: In Reply:—
Anesthesiology 5 2003, Vol.98, 1295. doi:
Anesthesiology 5 2003, Vol.98, 1295. doi:
In Reply:—
Thank you for the opportunity to reply to Rosemeier et al.  . The studies comparing general with regional anesthesia both involve only elderly patients. 1,2 Our own original study, ISPOCD1 3 confirmed that age was the predominant determinant of postoperative cognitive dysfunction (POCD) in the elderly. The current study on middle-aged patients allows for the possibility that other factors such as subtle drug side effects that would be obscured in an elderly population may be revealed.
The high incidence of POCD in the patients receiving epidural analgesia was contrary to our expectations. It was part of our primary data, and we were obliged to report it. We did not conclude that there was a causal association between epidural analgesia and POCD; rather, we suggested a hypothesis to explain our findings (hypotheses are by definition speculative). We clearly acknowledged that there may be explanations other than a direct causal relation between epidural analgesia and POCD to account for our findings (e.g.  , more major surgery) even though we took into account duration of surgery and blood loss.
We agree that there is strong evidence to support the use of epidural analgesia after major surgery especially in high-risk patients. We certainly did not caution against it but recommend keeping an open mind.
Rosemeier et al.  should not be alarmed that a multicenter study such as ours revealed significant differences in outcomes between participating centers. Patient selection and characteristics, hospital environment, policies, and protocols inevitably vary, and all may be relevant in the etiology of POCD. Differences in language, culture, testing personnel, and test timing may influence its assessment. The center statistic was included to compensate for these unknown factors in the analysis. In the multivariate analysis, we were looking for factors in addition to the differences between the centers. The analysis may be underpowered for some effects, but our observations were, nevertheless, statistically significant at the conventional level.
Larger and more detailed studies are required to explore all of the risk factors determining POCD that may or may not include epidural analgesia.
Raeder JC: Do regional anaesthesia protect against postoperative cognitive dysfunction? A randomized study of regional versus general anaesthesia in 525 elderly patients, Highlights in Regional Anaesthesia and Pain Therapy, XI 2002, Special Edition World Congress on Regional Anaesthesia and Pain Therapy. Edited by Van Zundert A, Rawal N. Cyprus, ESRA and Cyprint Ltd., 2002, pp 127–8
Williams-Russo P, Sharrock NE, Mattis S, Szatrowski TP, Charlson ME: Cognitive effects after epidural vs general anesthesia in older adults. A randomized trial. JAMA 1995; 274: 44–50Williams-Russo, P Sharrock, NE Mattis, S Szatrowski, TP Charlson, ME
Moller JT, Cluitmans P, Rasmussen LS, Houx P, Rasmussen H, Canet J, Rabbitt P, Jolles J, Larsen K, Hanning CD, Langeron O, Johnson T, Lauven PM, Kristensen PA, Biedler A, van Beem H, Fraidakis O, Silverstein JH, Beneken JE, Gravenstein JS: Long-term postoperative dysfunction in the elderly: ISPOCD1 study. Lancet 1998; 351: 857–61Moller, JT Cluitmans, P Rasmussen, LS Houx, P Rasmussen, H Canet, J Rabbitt, P Jolles, J Larsen, K Hanning, CD Langeron, O Johnson, T Lauven, PM Kristensen, PA Biedler, A van Beem, H Fraidakis, O Silverstein, JH Beneken, JE Gravenstein, JS