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Correspondence  |   September 2003
Antiemetic Prophylaxis for Office-based Surgery: Methodologic Concerns: In Reply
Author Affiliations & Notes
  • Paul F. White, Ph.D., M.D., F.A.N.Z.C.A.
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Article Information
Correspondence
Correspondence   |   September 2003
Antiemetic Prophylaxis for Office-based Surgery: Methodologic Concerns: In Reply
Anesthesiology 9 2003, Vol.99, 759-760. doi:
Anesthesiology 9 2003, Vol.99, 759-760. doi:
In Reply:—
We appreciate the interest of Alhashemi and Mujallid in our recent article examining the use of drug combinations for antiemetic prophylaxis of outpatients undergoing office-based surgery. 1 However, we think that the authors’ methodologic concern is simply invalid.
First, the potential for recall bias was apparently based on an erroneous assumption that patients did not record the episodes of nausea and vomiting that occurred after discharge from the office-based surgery facility. Although the postdischarge information regarding episodes of postoperative nausea and vomiting (PONV) was obtained by a telephone interview at 24 h after discharge, the patients were instructed to record all episodes of PONV at home. It is not clear why this fairly “standard” postdischarge evaluation procedure could be a “methodologic concern.” Although “recall bias” may be a valid issue for patients with cerebral impairment, we excluded  all patients with neurologic disorders.
Second, the authors’ suggestion that dolasetron produced “a 39% reduction in PONV” is very misleading. We believe it has no clinical relevance in the interpretation of these findings, because it fails to take into account that this difference was based on a very small number of patients. In our study, only one or two fewer patients in the dolasetron and ondansetron groups developed PONV before or after discharge, respectively, compared to the control group. Are Alhashemi and Mujallid suggesting that this difference could be of “clinical” significance? Inasmuch as only five patients in the control group developed PONV in the 24-h evaluation period, a difference of only one to three patients between groups would represent a 20–60% change! Although this may seem to be a large percentage  difference, it is clinically insignificant.
As previously discussed in an editorial, 2 the use of a combination of two or more antiemetic drugs for routine antiemetic prophylaxis seems to be warranted for outpatient populations considered to be “at risk” for developing PONV. In this outpatient surgery population (involving a variety of superficial, nongynecologic, and nonotolaryngologic procedures), it would seem that the addition of the 5-HT3antagonist to a two-drug regimen consisting of low-dose droperidol and dexamethasone failed to produce either a clinically or statistically significant benefit before or after discharge from the office-based surgery facility. It is entirely possible that we would have obtained a different  result if we had studied an outpatient population at higher  risk of developing PONV (e.g.  , those undergoing laparoscopic or otolaryngologic procedures).
Finally, we encourage Drs. Alhashemi and Mujallid to perform a randomized, double-blind, placebo-controlled study in a similar  (or higher-risk) patient population using the same anesthetic technique. We would hope they would then be satisfied that the question we posed in our study has indeed been adequately answered!
References
Tang J, Chen X, White PF, Wender RH, Ma H, Sloninsky A, Naruse R, Kariger R, Webb T, Zaentz A: Antiemetic prophylaxis for office-based surgery: Are the 5-HT3receptor antagonists beneficial? A nesthesiology 2003; 98: 293–8Tang, J Chen, X White, PF Wender, RH Ma, H Sloninsky, A Naruse, R Kariger, R Webb, T Zaentz, A
White PF, Watcha MF: Postoperative nausea and vomiting: Prophylaxis versus  treatment (editorial). Anesth Analg 1999; 89: 1337–9White, PF Watcha, MF