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Onset time, recovery duration, and drug cost with four different methods of inducing general anesthesia |
Fleischmann E, Akca O, Wallner T, Arkilic C F, Kurz A, Hickle R S, Zimpfer M, Sessler D I |
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Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology Use of sevoflurane and nitrous oxide from a rebreathing bag (Sevo/Bag) or sevoflurane and nitrous oxide from a circle system (Sevo/Circle) as induction anaesthetics in women patients undergoing short gynaecological procedures with an anticipated duration of 10-20 minutes.
Economic study type Cost-effectiveness analysis.
Study population Women patients undergoing short gynaecological procedures with an anticipated duration of 10-20 minutes.
Setting Hospital. The economic study was carried out in Vienna, Austria.
Dates to which data relate The dates of the effectiveness and resource use data were not specified. The price year was 1998.
Source of effectiveness data Effectiveness data were derived from a single study.
Link between effectiveness and cost data Costing was prospectively performed on the same patient sample as that used in the effectiveness analysis.
Study sample Power calculations were not used to determine the sample size. The study sample was 80 patients randomly allocated to undergo one of the 4 types of anaesthetic (n=20). The average (SD) age of the patients in the groups was: thiopental 43 (13) years, propofol 41 (11) years, Sevo/Circle 38 (13) years, and Sevo/Bag 43 (10) years.
Study design This was a randomised controlled study, carried out in a single centre. The duration of the follow-up was until discharge. No loss to follow-up was reported. The treating anesthesiologists and the investigator in charge of postoperative measurements were blinded to group assignment.
Analysis of effectiveness The principle used in the analysis of effectiveness was intention to treat. The clinical outcomes were induction time, awakening (minutes after sevoflurane discontinued), recovery duration, and nausea and vomiting requiring treatment. A modification of the Aldrete and Kroulik scoring system and a conventional visual analog scale were used to evaluate fitness for discharge and postoperative pain, respectively. Patients in each group were reported to be similar in terms of morphometric and demographic features, and Mallampati scores, anesthetic maintenance, and duration of anesthesia.
Effectiveness results Induction times (SD) were: thiopental group, 124 (45) seconds; propofol group, 140 (40) seconds; Sevo/Circle group, 155 (40) seconds; and Sevo/Bag group, 129 (22) seconds, (not significant across the four techniques).
Recovery duration (minutes after discontinuing anesthesia) were: thiopental group, 17 (6); propofol group, 14 (4); Sevo/Circle group, 12 (3); and Sevo/Bag group, 11 (2). The difference between each of the sevoflurane (Circle or Bag) groups and the thiopental group was statistically significant.
The times for awakening (minutes) were: thiopental group, 9 (4); propofol group, 8 (3); Sevo/Circle group, 7 (3); and Sevo/Bag group, 6 (2). The difference between the Sevo/circle group and the thiopental group, and between the Sevo/bag and propofol groups were significant.
The percentage of nausea/vomiting was: thiopental group, 15%/0%; propofol group, 0%/0%; Sevo/Circle group, 50%/25%; and Sevo/Bag group, 55%/30%.
Clinical conclusions The study data indicate that induction times are comparable across methods but that awakening after sevoflurane is faster. Recovery duration was significantly longer in patients given thiopental than in those given sevoflurane.
Measure of benefits used in the economic analysis No summary benefit measure was identified in the economic analysis, and only separate clinical outcomes were reported.
Direct costs Costs were not required to be discounted due to the short time horizon of the study. Some resource use data were reported separately from the costs. Cost items were reported separately. Cost analysis covered the costs of induction drug, sevoflurane maintenance, and cost of ondansetron (4-8 mg) used in the treatment of postoperative nausea and vomiting. The perspective adopted in the cost analysis was not explicitly specified. Drug cost data were based on average United States wholesale prices. November 1998 price data were used. The cost of nitrous oxide was deemed common and therefore not included in the analysis. The cost of the 5-L rebreathing bag was not included in the analysis.
Statistical analysis of costs One-way analysis of variance and Scheffe's F-tests were used to compare the study groups in terms of costs.
Estimated benefits used in the economic analysis Cost results The average (SD) total costs were: thiopental group, $14.5 (9.5); propofol group, $20.1 (7.8); Sevo/Circle group, $25.1 (12.1); and Sevo/Bag group $19.4 (18.1). The difference between the Sevo/circle group and the thiopental group was statistically significant.
Synthesis of costs and benefits Costs and benefits were not combined.
Authors' conclusions No single technique was obviously superior, which suggests that the anesthetic induction technique for individual patients may best be chosen based on the relative importance of recovery duration, cost, and avoidance of nausea and vomiting.
CRD COMMENTARY - Selection of comparators A justification was given for the choice of the comparators. They were regarded as the conventional techniques in the context in question.
Validity of estimate of measure of benefit The internal validity of the effectiveness results is likely to be high due to the randomised design adopted in the study but, against this, should be balanced the main limitation of the study which is the dependence of the recovery features on type and duration of surgery (as acknowledged by the authors). The study was a cost-consequences analysis.
Validity of estimate of costs Quantities were not fully reported separately from the costs. Adequate details of the methods of cost estimation were given. The major limitation of the cost analysis, as acknowledged by the authors, was the dependence of the cost results on the type of antiemetic used (not using a less expensive and equally effective antiemetic such as droperidol).
Other issues The authors addressed the issue of generalisability by noting that the effectiveness data were dose-specific and that the cost data were country-specific. The economic study seemed to necessitate the use of a cost-effectiveness measure in order to rank strategies, since the analysis showed a lack of dominant strategies.
Implications of the study None of the four techniques analysed was obviously superior, which suggests that the anaesthetic induction technique for individual patients should be chosen based on other criteria such as the relative importance of recovery duration, cost, and avoidance of nausea and vomiting.
Source of funding Supported by National Institutes of Health Grant GM58273, the Joseph Drown Foundation (Los Angeles, CA), the Fonds zur Forderung der Wissenschaftlichen Forschung (Vienna, Austria), Apotheus Laboratories Ltd, and Abbott GesmbH (Vienna, Austria).
Bibliographic details Fleischmann E, Akca O, Wallner T, Arkilic C F, Kurz A, Hickle R S, Zimpfer M, Sessler D I. Onset time, recovery duration, and drug cost with four different methods of inducing general anesthesia. Anesthesia and Analgesia 1999; 88(4): 930-935 Indexing Status Subject indexing assigned by NLM MeSH Adult; Anesthesia, General /economics /methods; Anesthesia, Obstetrical /economics /methods; Anesthetics, Inhalation /adverse effects /economics; Anesthetics, Intravenous /adverse effects /economics; Female; Humans; Methyl Ethers /adverse effects /economics; Middle Aged; Propofol /adverse effects /economics; Thiopental /adverse effects /economics; Time Factors AccessionNumber 21999000763 Date bibliographic record published 31/12/2000 Date abstract record published 31/12/2000 |
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