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Reply to “Inaccurate citation should have been evident”
- Wei-Zen Sun, [Yu-Chang Yeh] (16 November 2008)
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Inaccurate citation should have been evident
- Gordon B Drummond (3 November 2008)
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Wei-Zen Sun National Taiwan University Hospital, [Yu-Chang Yeh]
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We would like to thank Dr. Drummond for his correction on two evidently mistaken citations in our paper.1 While our cited references clearly disagreed with the concept of equivalent efficacy between nalbuphine and morphine, as pointed out by Dr. Drummond, the correct citations were accidentally misplaced through reference management. Unfortunately, mistaken contents were overlooked during subsequent proof- reading and thereafter. The corrected citations would support our statement that both drugs are equally effective in postoperative settings.2,3 In the first paper, Ho and colleagues demonstrated that both PCA nalbuphine and morphine are effective in the treatment of postoperative pain in Chinese gynecologic patients undergoing hysterectomy or myomectomy. In another paper, Kruszynski and colleagues found that nalbuphine, in a proper dose, is an analgesic equal to morphine with respect to analgesic effectiveness and time of pharmacological action in women undergoing abdominal gynecologic operations. In another report, Minai and colleagues showed that nalbuphine provides better haemodynamic stability and better intraoperative analgesia, recovery profile and postoperative pain relief compared to morphine in patients undergoing total abdominal hysterectomy.4 However, we did not cite this paper as this surprising finding may occur as a result of an unusual protocol that both drugs were used throughout the entire perioperative period. The conflicting reports whether nalbuphine and morphine is equally effective in analgesic efficacy remains controversial in the literature. We agree with Dr. Drummond that the intensity of pain plays a major role to the assessment of drug efficacy in any setting of acute pain model. In drug with ceiling effect, such as nalbuphine, favourable analgesic effect could be obtained among gynecologic patients with mild to moderate pain, as reported by Ho and Kruszynski and colleagues.2, 3 However, insufficient responses are usually observed when moderate to severe pain is treated. Our observation concords with Dr. Drummond’s comment by showing that more patients suffered from insufficient analgesia in Groups 4 and 5 although the events of insufficient analgesia were not statistically different among the five groups. Altogether, despite the mistaken citations, we carefully concluded by stating “that nalbuphine is a partial agonist and has its effect at the kappa receptor. This is important as it suggests a ceiling effect will be present in the response produced. Furthermore, the interaction between nalbuphine and morphine needs to be investigated for other populations or more advanced surgery.”1 Once again, we apologize for inserting conflicting citations and appreciate the opportunity to correct the erratum. Reference list: 1. Yeh YC, Lin TF, Lin FS, Wang YP, Lin CJ, Sun WZ. Combination of opioid agonist and agonist-antagonist: patient-controlled analgesia requirement and adverse events among different-ratio morphine and nalbuphine admixtures for postoperative pain. Br J Anaesth 2008; 101: 542-8 2. Ho ST, Wang JJ, Liu HS, Hu OY, Tzeng JI, Liaw WJ. Comparison of PCA nalbuphine and morphine in Chinese gynecologic patients. Acta Anaesthesiol Sin 1998; 36: 65-70 3. Kruszynski Z, Jaworska-Grajek M, Wiewiorowski K, Warzybok K. Comparative studies of nalbuphine and morphine in the therapy of postoperative pain in gynecology. Ginekol Pol 1989; 60: 216-22 4. Minai FN, Khan FA. A comparison of morphine and nalbuphine for intraoperative and postoperative analgesia. J Pak Med Assoc 2003; 53: 391- 6 Conflict of Interest:None declared |
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Gordon B Drummond University of Edinburgh
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I was surprised by the statement Yeh and colleagues make in their paper1 considering mixtures of nalbuphine and morphine. They state: ‘Comparative trials have shown that both nalbuphine and morpine are equally effective on pain relief’, followed by a citation of two papers to support this statement. The first paper they cite2 was a study of day surgery patients given incremental doses of morphine, dezocine, or nalbuphine for pain after arthroscopy (i.e., treatment for moderate pain). The summary of this paper states “Dezocine and morphine are more efficacious than nalbuphine”. The second paper cited3 was not a comparative study, but a dose-response study using increasing infusion rates of nalbuphine given to patients after abdominal surgery. (i.e., treatment for severe pain). This study showed that progressive increases in the blood levels of nalbuphine did not improve analgesia. The companion study,4 in the adjacent article in the journal (which was not cited by Lin and colleagues) was a comparative study of nalbuphine, but the comparator was buprenorphine. That study had to be stopped prematurely. Nine out of 29 patients allocated to receive nalbuphine were withdrawn because of inadequate pain control, and the conclusion was “The present study suggests that nalbuphine, as a sole analgesic, is inappropriate for patients after abdominal surgery”. I suspect that clinical experience would suggest that the same could not be said for morphine. Other studies have shown that nalbuphine is NOT as effective as morphine.5 How therefore can Lin and colleagues state that nalbuphine and morphine are equally effective? They may have been misled by early studies6 which only studied moderate pain: under these circumstances, many analgesics are efficacious. But they shouold have been aware of the content of the papers that they cited. Even the title of the second citation3 indicates that the paper was not a comparative study. Did neither the referees nor the editor not suspect that this paper was inappropriately cited? Inaccurate citation of published papers has a corrupting effect on the body of scientific knowledge. Our studies3 4 subjected patients to treatment that was inadequate, which was a distressing conclusion since we had asked them to participate in the belief that there was no known difference, but perhaps understandable on the basis of the knowledge that we had at the time. (The paper by Bahar and colleagues5 had not been published when our study was started) However it’s even more distressing to think that others might now be misled by misleading statements supported by inaccurate citations, published when previous work now shows that these agents are NOT equivalent. This error should be acknowledged with an erratum. Reference List (1) Yeh YC, Lin TF, Lin FS, Wang YP, Lin CJ, Sun WZ. Combination of opioid agonist and agonist-antagonist: patient-controlled analgesia requirement and adverse events among different-ratio morphine and nalbuphine admixtures for postoperative pain. Br J Anaesth 2008; 101: 542- 8. (2) Cohen RI, Edwards WT, Kezer EA, Ferrari DA, Liland AE, Smith ER. Serial intravenous doses of dezocine, morphine, and nalbuphine in the management of postoperative pain for outpatients. Anesth Analg 1993; 77: 533-9. (3) Pugh GC, Drummond GB. A dose-response study with nalbuphine for pain in patients after upper abdominal surgery. Br J Anaesth 1987; 59: 1356-63. (4) Pugh GC, Drummond GB, Elton RA, Macintyre CC. Constant i.v. infusions of nalbuphine or buprenorphine for pain after abdominal surgery. Br J Anaesth 1987; 59: 1364-74. (5) Bahar M, Rosen M, Vickers MD. Self-administered nalbuphine, morphine and pethidine. Comparison, by intravenous route, following cholecystectomy. Anaesthesia 1985; 40: 529-32. (6) Beaver WT, Feise GA. A comparison of the analgesic effect of intramuscular nalbuphine and morphine in patients with postoperative pain. J Pharmacol Exp Ther 1978; 204: 487-96. Conflict of Interest:DuPont (UK) funded the research discussed in this letter. I did not receive any personal payment. |
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