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Pre-operative optimisation employing dopexamine or adrenaline for patients undergoing major elective surgery: a cost-effectiveness analysis |
Fenwick E, Wilson J, Sculpher M, Claxton K |
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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 Patients undergoing major elective surgery were given preoperative optimised oxygen delivery, using either adrenaline or dopexamine. They were admitted to an intensive care or high dependency unit at least 4 hours before surgery where they received haemodynamic monitoring, fluid optimisation and inotrope optimisation. The inotropic support was continued for 12 to 24 hours post-surgery. A comparator group of patients were given routine perioperative care, as determined by the surgeon and anaesthetist.
Study population Patients were included in the study if they were undergoing major elective surgery in general surgery, vascular surgery, or urology and had been identified as being at high risk of developing perioperative complications. Full details of the patients were published elsewhere (Wilson et al., see Other Publications of Related Interest).
Setting The setting was secondary care. The economic study was carried out in the UK.
Dates to which data relate The dates to which the effectiveness and resource evidence related were not given. The prices used were from 1999-2000.
Source of effectiveness data The effectiveness data were derived from a single study.
Link between effectiveness and cost data The costing was carried out retrospectively on the same patient sample as that used in the effectiveness analysis.
Study sample No power calculations and no method of sample selection were reported in the current paper. There were 138 patients in the study. Of these, 46 were randomised to receive pre-op using adrenaline, 46 to receive pre-op using dopexamine, and 46 to receive standard treatment.
Study design This was a randomised controlled trial in which the patients were stratified by three surgical sub-groups (vascular, upper gastrointestinal and other abdominal). The number of centres involved was not reported. The patients were followed up for 2 years after surgery. One patient in the adrenaline group was not included in the study because no resource data could be obtained for them. Double-blinding was employed with respect to the type of inotrope used in the pre-op.
Analysis of effectiveness The basis of the analysis was intention to treat. The primary health outcomes used were mortality and morbidity, defined as the percentage of patients developing one or more of a predefined range of complications. The information on the comparability of the patient groups was given elsewhere (Wilson et al., see Other Publications of Related Interest).
Effectiveness results The 28-day mortality rate was 4% in the dopexamine group, 2% in the adrenaline group, and 17% in the standard treatment group.
The 2-year mortality rate was 28% in the dopexamine group, 24% in the adrenaline group, and 33% in the standard treatment group.
The morbidity rate was 30% in the dopexamine group, 53% in the adrenaline group, and 61% in the standard treatment group.
At hospital discharge, mortality was 3% in the pre-op groups and 17% in the standard care group, (p=0.007).
The full results were published elsewhere (Wilson et al., see Other Publications of Related Interest).
Clinical conclusions Mortality was lower among patients receiving pre-op when comparing pre-op with standard care, and was lower among adrenaline patients when comparing the pre-op groups (adrenaline and dopexamine). However, morbidity was lower among patients receiving dopexamine than among those receiving adrenaline or standard treatment.
Measure of benefits used in the economic analysis The measure of benefit used was the life-years gained at 2 years post-surgery.
Direct costs The hospital costs were estimated and obtained from actual data. The costs were broken down into all their components. More specifically, days in the ward, intensive care unit and high dependency unit, drugs, investigations (e.g. full blood counts, clotting studies, cross match, and urea and electrolytes), infusions, surgery, arterial blood gas and total parenteral nutrition, and pre-op. Hotel costs were also estimated. These included fixed costs, staff costs, estate costs, overheads and the cost of monitoring equipment. The cost of any further surgery to treat a complication or related event was included. The quantities and the costs were analysed separately. The resource quantity data were derived from patient records and clinical notes, while the unit cost data were taken from an NHS hospital. Discounting was not carried out as the costs were incurred during less than 2 years. The price year was 1999-2000.
Statistical analysis of costs No statistical analysis of the costs was carried out.
Indirect Costs No indirect costs were included.
Sensitivity analysis No sensitivity analysis was carried out.
Estimated benefits used in the economic analysis Pre-op resulted in 1.68 life-years post-surgery (1.74 with adrenaline and 1.62 with dopexamine) and standard care resulted in 1.46 life-years post-surgery. Thus, pre-op resulted in 0.22 additional life-years compared with standard treatment.
Using adrenaline resulted in 0.12 life-years compared with dopexamine.
Cost results The mean cost was Euro 16,965 for patients receiving standard care and Euro 11,310 for patients receiving pre-op (Euro 13,820 for adrenaline and Euro 9,247 for dopexamine). On average, pre-op was Euro 5,655 cheaper than standard treatment.
The costs were originally in pounds sterling () and were converted to Euros at a rate of 1 = Euro 1.631.
The costs were calculated for 2 years after surgery and included hospital readmissions for 6 months after surgery.
The costs of adverse effects were dealt with in the costing.
Synthesis of costs and benefits On average, pre-op was cheaper than standard treatment and resulted in increased life-years.
When repeated sampling was carried out on the cost-effectiveness ratios, the probability that pre-op was cheaper than standard treatment was 98%. The probability that pre-op dominated standard care was 93%.
When adrenaline, with its higher costs but higher survival time, was compared with dopexamine, the incremental cost-effectiveness ratio was Euro 38,108 per life-year.
When decision-makers are willing to pay Euro 32,620 per life-year, the probability that pre-op is optimal was 99.35% and the probability that standard patient care is optimal was 0.65%.
If decision-makers are unwilling to pay anything for an additional life-year, the probability that pre-op with dopexamine is optimal was 99.6%.
If the decision-makers are willing to pay Euro 32,620 per life-year gained, the probability that pre-op with dopexamine is optimal is 57.2%, compared with 42.6% for pre-op adrenaline and 0.2% for standard patient treatment.
Authors' conclusions It is very likely that preoperative optimisation (pre-op) is the optimal strategy for the type of patients in this study.
CRD COMMENTARY - Selection of comparators The selection of the comparator was implicitly justified by it being current practice in many settings. You should decide if the comparator represents current practice in your own setting.
Validity of estimate of measure of effectiveness The effectiveness data were derived from a single study. The study design, a randomised controlled trial, was appropriate for the study question. From the limited information given in the current paper, it was not possible to determine whether the study sample was representative of the study population. In addition, there was no information on the comparability of the patients groups. The analysis of effectiveness was handled credibly, but the current paper gave little statistical information on the comparisons between the groups. There were no other sources of effectiveness data.
Validity of estimate of measure of benefit One measure of benefit, the life-years gained, was used. This was taken directly from one of the effectiveness estimates and did not take the other effectiveness measure, morbidity, into consideration.
Validity of estimate of costs From the perspective adopted in the paper (i.e. the NHS), the authors omitted all costs incurred after hospital discharge, an omission which they acknowledged. All hospital costs were included in the analysis, thus giving an accurate picture of that particular component in the total health system costs. The costs and the quantities were reported separately, which will enable decision-makers to assess the generalisability of the cost results. The resource use quantities were taken from the single study using patient records, and no other source was used. The prices were taken from one NHS hospital. No statistical analysis, sensitivity analysis, or any other analysis of the quantities or prices was carried out, thus limiting the generalisability of the results. The authors performed appropriate currency conversions. Discounting was not necessary as the costs were incurred during one year. The price year was reported.
Other issues The authors made appropriate comparisons of their results with those from other studies. They discussed the issue of generalisability in relation to using the costs of one particular hospital. The authors did not give detailed effectiveness results as they had already been published. The authors' conclusions generally reflected the scope of the analysis, apart from the fact that they did not draw attention to the higher morbidity among adrenaline patients than dopexamine patients. The authors pointed out that the examination of patient records retrospectively for resource use data can lead to incomplete information, but they did not consider that the results of this study would be adversely affected by this incompleteness.
Implications of the study The authors concluded that high-risk patients undergoing major elective surgery should be given pre-op, as it will probably cost less and lead to better outcomes in terms of morbidity and mortality. The authors stated that the choice between adrenaline and dopexamine partly depends on the value that decision-makers put on extra life-years for the patient group being studied. They recommended further research in order to make an informed decision as to which kind of pre-op should be chosen.
Source of funding The original clinical trials were funded by the National Lotteries Hospital Fund. The economic study was funded, without restriction, by Elan Pharma (UK) and Edwards Lifesciences.
Bibliographic details Fenwick E, Wilson J, Sculpher M, Claxton K. Pre-operative optimisation employing dopexamine or adrenaline for patients undergoing major elective surgery: a cost-effectiveness analysis. Intensive Care Medicine 2002; 28(5): 599-608 Other publications of related interest Wilson J, Woods I, Fawcett J, Whall R, Morris C, McManus E. Reducing the risk of major elective surgery: randomised controlled trial of preoperative optimisation of oxygen delivery. BMJ 1999;318:1099-103.
Indexing Status Subject indexing assigned by NLM MeSH Bayes Theorem; Cost-Benefit Analysis; Dopamine /analogs & Elective Surgical Procedures /adverse effects /mortality; Epinephrine /therapeutic use; Health Services Research; Hospital Costs; Hospital Mortality; Humans; Length of Stay /statistics & Oxygen /administration & Preoperative Care /economics /methods; Randomized Controlled Trials as Topic; Retrospective Studies; Vasoconstrictor Agents /therapeutic use; Vasodilator Agents /therapeutic use; derivatives /therapeutic use; dosage; numerical data AccessionNumber 22002001053 Date bibliographic record published 30/06/2005 Date abstract record published 30/06/2005 |
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