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ANALGESIA

The Limited Efficacy of Tramadol in Postoperative Patients: A Study of ED₈₀ Using the Continual Reassessment Method

From the AP-HP, Univ Paris-Sud, Hôpital Bicêtre, Département d'Anesthésie-Réanimation, France F-94275, Le Kremlin-Bicêtre, France.

Address correspondence and reprint requests to Jean-Xavier Mazoit, MD, PhD, Univ Paris-Sud, Hôpital Bicêtre, Département d'Anesthésie-Réanimation, France F-94275, Le Kremlin-Bicêtre, France. Address e-mail to jean-xavier.mazoit{at}kb.u-psud.fr.

Abstract

BACKGROUND: The aim of this study was to reevaluate the efficacy of tramadol for postoperative analgesia and to determine its ED₈₀ (the clinical dose for which 80% of the patients had their pain adequately relieved) using the Continual Reassessment Method. Because the preliminary results of the first 24 patients were contradictory to the literature, we performed a second trial to verify and validate our data.

METHODS: The study was double-blind and prospective. Participants were allocated to a dose of tramadol by 3-patient cohorts, in order of inclusion. The dose of tramadol received in each cohort was determined by the reaction of all previous patients. Five doses were chosen before beginning, with a probability of a positive reaction associated with each: 60 (0.4), 100 (0.55), 140 (0.7), 190 (0.8), and 260 mg (0.9). Tramadol was considered effective if the numeric pain scale was 3/10 at T30.

RESULTS: The effective dose in 80% of patients was 260 mg for both trials. The probability of success of the 260 mg dose was 0.699 (95% credibility interval, 0.471–0.874) and 0.657 (95% credibility interval, 0.437–0.853) for trial 1 and trial 2, respectively.

CONCLUSION: Tramadol used as a sole drug cannot be considered the drug of choice after moderately painful surgery. The doses needed to relieve pain in 80% of patients are much larger than the usual dose of 100 mg. The Continual Reassessment Method allowed us to determine the ED₈₀ of tramadol with a limited number of patients.