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A cost comparison of methohexital and propofol for ambulatory anesthesia |
Sun R, Watcha M F, White P F, Skrivanek G D, Griffin J D, Stool L, Murphy M T |
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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 Induction of anesthesia with the anaesthetic drugs propofol and methohexital.
Economic study type Cost-effectiveness analysis.
Study population Healthy ASA physical status I and II adult patients undergoing ambulatory surgical procedures. Patients with significant cardiovascular, pulmonary, renal, hepatic or neurologic disease, those with a body weight 100% greater than the norm or patients with a history of drug or alcohol abuse were excluded from the analysis.
Setting Hospital. The economic analysis was conducted in Dallas, Texas, USA.
Dates to which data relate Dates for the collection of effectiveness and resource data do not appear to be stated. The base price years used were not stated.
Source of effectiveness data Effectiveness data were derived from a single study.
Link between effectiveness and cost data Cost data were collected prospectively using the same patient sample as in the clinical analysis.
Study sample 120 patients were randomly assigned to four groups and there were 30 patients in each group. Power calculations were used to determine that 28 patients were needed in each group to have an 80% chance of observing a 20% reduction in mean costs of anesthesia at a significance level of p<=0.05.
Study design The study was a single centre randomised controlled trial. The duration of follow-up was 24 hours after discharge. Randomisation was performed using a computer generated numbers table. No loss to follow-up was reported in the analysis.
Analysis of effectiveness The analysis of effectiveness was based on intention to treat. The primary health outcomes used were incidence of post-operative side effects such as nausea and vomiting, the need for post-operative medications, and the length of recovery time. At analysis there were no significant demographic or clinical differences between patients in the four groups nor in the type of surgical procedures which they were to receive.
Effectiveness results There were no significant differences in the incidence of post-operative nausea and vomiting between patients who received propofol and those who received methohexital (49% compared with 53%, p=0.84). Furthermore there were no significant difference in pain, recovery times or length of stay within the post-anesthesia care unit or in the need for post-operative medications such as analgesics and anti emetics.
Clinical conclusions Recovery times and post-operative side effects were comparable between patients inducted using either methohexital or propofol.
Measure of benefits used in the economic analysis Since the effectiveness analysis showed no difference in effectiveness/clinical benefit between the intervention and the comparator, the economic analysis was based on the difference in costs only (cost-minimization analysis).
Direct costs Costs of anesthesia drugs, post anesthesia care drugs, drug wastage, emesis and pain management and nursing labour costs were included in the analysis. Discounting was not used in the analysis due to the short duration of the study. Anesthesia drug costs and post anesthesia drug costs were taken from actual acquisition costs at the study institution. Costs of sevoflurane and desflurane used were estimated using a previously published formula. Costs were determined both from the perspective of an ambulatory surgical centre and the pharmacy manager. The base price year used in the analysis is not reported.
Estimated benefits used in the economic analysis Cost results Total mean costs per patient were significantly lower in the methohexital/desflurane groups ($68.97 +/- $20.74) and methohexital/sevoflurane groups ($75.86 +/- $27.63) than in both the propofol desflurane ($89.78 +/- $20.78) and propofol sevoflurane groups ($100.66 +/- $36.43) respectively (p<0.05). The cost advantage of methohexital/desflurane would have been even greater had lower fresh gas flow rates of 1 L/minute or less been adopted rather than 2 L/min. which was recommended when using sevoflurane.
Synthesis of costs and benefits Authors' conclusions Methohexital followed by either desflurane and sevoflurane is comparable in clinical outcomes to propofol followed by desflurane or sevoflurane when used for the induction and maintenance of anesthesia in patients, and is a significantly less costly option. Methohexital followed by desflurane was observed to be the least costly option, particularly as low flow rates of 1L/minute or less for desflurane can be used whereas the US Federal Drug Administration recommends that a minimum rate of 2 L/min. is required when using sevoflurane.
CRD COMMENTARY - Selection of comparators A justification was provided by the authors for the comparator used. Propofol has previously been shown to lead to a decreased incidence of post-operative nausea and vomiting compared with older anaesthetics. Methohexital has been shown to have improved recovery times for patients compared with thiopental, an anaesthetic which has been compared with propofol previously.
Validity of estimate of measure of benefit Benefits were determined using a randomised controlled trial, and furthermore power calculations were used to determine sample size. Validity is therefore likely to be high. The authors noted, however, that they did not consider potential complications such as seizures or arrhythmias which, although rare, would involve additional costs.
Validity of estimate of costs Although sufficient details were provided of the type and sources of costs provided, price years used in the analysis do not appear to have been reported. Future analyses may wish to consider costs to others in society arising from differences in recovery time and side effects and associated productivity losses.
Other issues Dates for the collection of effectiveness and cost data do not appear to have been reported. The cost results of the analysis may not be generalisable outside the setting of the study institution. A sensitivity analysis, in particular to identify cost thresholds, may be useful to those operating with different resource and cost structures.
Implications of the study Cost differences were found to be primarily due to the acquisition costs of drugs used for the induction. If these alter in favour of propofol its use may become more cost-effective.
Source of funding Educational grant from Jones Medical, St Louis, MO.
Bibliographic details Sun R, Watcha M F, White P F, Skrivanek G D, Griffin J D, Stool L, Murphy M T. A cost comparison of methohexital and propofol for ambulatory anesthesia. Anesthesia and Analgesia 1999; 89(2): 311-316 Indexing Status Subject indexing assigned by NLM MeSH Adult; Ambulatory Surgical Procedures; Anesthesia Recovery Period; Anesthesia, General /economics; Anesthetics, Combined; Anesthetics, Inhalation; Anesthetics, Intravenous /economics; Cost-Benefit Analysis; Drug Costs; Female; Humans; Isoflurane /analogs & Male; Methohexital /economics; Methyl Ethers; Middle Aged; Propofol /economics; derivatives AccessionNumber 21999001538 Date bibliographic record published 31/03/2000 Date abstract record published 31/03/2000 |
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