|
Cost-effectiveness of prophylactic antiemetic therapy with ondansetron, droperidol, or placebo |
Hill R P, Lubarsky D A, Phillips-Bute B, Fortney J T, Creed M R, Glass P S, Gan T J |
|
|
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 Three prophylactic intravenous regimens for post-operative nausea and vomiting (PONV) were assessed. The three regiments were ondansetron 4 mg, droperidol 0.625 mg, and droperidol 1.25 mg.
Type of intervention Primary prevention (anti-emetic therapy).
Economic study type Cost-effectiveness analysis.
Study population The study population comprised patients classified as American Society of Anesthesiologists physical status I or II, who were aged between 18 and 65 years, and were undergoing general anaesthesia outpatient procedures of a duration of no more than 2 hours. Only patients undergoing those procedures considered to have high emetogenic potential were included in the study.
Setting The setting of the study was an ambulatory surgical facility in a tertiary care institution. The economic study was carried out at 50 institutions in North America.
Dates to which data relate The period during which the effectiveness and resource use data were collected was not reported. The price year was not reported.
Source of effectiveness data The effectiveness evidence were derived from a single study.
Link between effectiveness and cost data The costing was undertaken prospectively on the same patient sample as that used in the effectiveness analysis.
Study sample Power calculations to determine the sample size were not performed. A total of 2,061 patients were enrolled in the study. There were 515 patients in the 4 mg-ondansetron group, 518 patients in the 0.625 mg-droperidol group, 510 patients in the 1.25 mg-droperidol group, and 518 patients in the placebo group.
Study design This was a randomised, double-blind, placebo-controlled, multicentre clinical trial. The method of randomisation was not reported. The study was carried out at 50 institutions in North America. The assessment of the patients was conducted in the post-operative anaesthesia care unit by independent study personnel, and was continued for 2 hours. The patients were followed for 24 hours after discharge. The loss to follow-up was not reported.
Analysis of effectiveness The basis of the analysis of the clinical study was not reported. It would appear that all of the patients included in the study were accounted for in the analysis, implying that it was conducted on an intention to treat basis. The primary health outcomes were the percentages of PONV-free patients, PONV- and side effect-free patients, and emesis-free patients associated with the three anti-emetic therapies, over placebo. Patient satisfaction was also assessed. The authors stated that there were no statistically significant differences across the study groups in terms of their demographics.
Effectiveness results The percentages of PONV-free patients were 39% in the 4 mg-ondansetron group (11% higher than placebo), 43% in the 0.625 mg-droperidol group (15% higher than placebo), and 50% in the 1.25 mg-droperidol group (22% higher than placebo).
The percentages of PONV- and side effect-free patients were 20% in the 4 mg-ondansetron group (3% higher than placebo), 24% in the 0.625 mg-droperidol group (7% higher than placebo), and 28% in the 1.25 mg-droperidol group (11% higher than placebo).
The percentages of emesis-free patients were 62% in the 4 mg-ondansetron group (16% higher than placebo), 63% in the 0.625 mg-droperidol group (17% higher than placebo), and 69% in the 1.25 mg-droperidol group (23% higher than placebo).
Patient satisfaction was statistically higher in the three therapy groups than in the placebo group.
Clinical conclusions The three anti-emetic therapies were more effective than placebo in improving all the health outcomes assessed. In particular, droperidol 1.25 mg was the most effective treatment.
Modelling A decision tree model was derived from the literature to partition each study group into subgroups. The criteria for partitioning were the presence of PONV after prophylactic therapy, the need for additional rescue anti-emetic therapy despite prophylaxis, the success of rescue anti-emetic therapy, the occurrence of side effects, and the treatment of side effects. Overall, 12 mutually exclusive subgroups (paths) were identified. The probability of each patient having a specific outcome was calculated.
Measure of benefits used in the economic analysis The benefit measures used in the economic analyses were the incremental percentages of PONV-free patients, PONV- and side effect-free patients, and emesis-free patients associated with the three anti-emetic therapies, over placebo. These were derived directly from the effectiveness analysis.
Direct costs Discounting was not carried out due to the short timeframe of the study. The unit costs and the quantities of resources used were reported separately. The cost/resource boundary adopted was that of the ambulatory surgical facility. The cost items included in the analysis were materials, hospital (post-operative anaesthesia care unit delay and admission), personnel and drugs (ondansetron and droperidol). The materials included the basin, glove, paper, linen and gown. The personnel costs were for the anaesthesiologist, registered nurse, aid, certified nurse anaesthetist, and licensed practice nurse. The costs relating to the treatment of side effects were also included.
The total costs were obtained from the decision model. The costs were mainly estimated using actual data derived from the hospital administration at Duke University (NC, USA). The cost of hospital stay was derived from published data. Data on the quantities were derived from the trial. The period during which the quantities of resources used were collected was not reported. No price year was used.
Statistical analysis of costs Statistical analyses of the total costs were carried out to test for statistical significance of the results.
Indirect Costs The indirect costs were not included.
Sensitivity analysis Sensitivity analyses were not explicitly carried out. However, the impact of excluding personnel costs from the cost analysis was tested.
Estimated benefits used in the economic analysis See the 'Effectiveness Results' section.
Cost results The mean (median) costs were $112.3 ($16.44) in the 4 mg-ondansetron group, $109.2 ($0.63) in the 0.625 mg-droperidol group, $104.0 ($0.51) in the 1.25 mg-droperidol group, and $164.1 ($51.2) in the placebo group.
The costs were statistically higher in the placebo group than in the three anti-emetic therapies. There was no statistically significant difference across the three active treatment costs.
When personnel costs were excluded, the median costs were $16.44 in the 4 mg-ondansetron group, $0.51 in the 0.625 mg-droperidol group, $0.51 in the 1.25 mg-droperidol group, and $20.41 in the placebo group.
Synthesis of costs and benefits An incremental cost-effectiveness analysis was carried out to combine the costs and the benefits. The costs per PONV-free patient were $286 in the 4 mg-ondansetron group, $251 in the 0.625 mg-droperidol group, $206 in the 1.25 mg-droperidol group, and $575 in the placebo group. The costs per PONV- and side effect-free patient were $551 in the 4 mg-ondansetron group, $457 in the 0.625 mg-droperidol group, $375 in the 1.25 mg-droperidol group, and $960 in the placebo group.
The incremental cost to gain an additional PONV-free patient over placebo was $149 with 4 mg-ondansetron, $3.4 with 0.625 mg-droperidol, and $2.3 with 1.25 mg-droperidol.
The incremental cost to gain an additional PONV- and side effect-free patient over placebo was $548 with 4 mg-ondansetron, $7.3 with 0.625 mg-droperidol, and $4.6 with 1.25 mg-droperidol.
The incremental cost to gain an additional emesis-free patient over placebo was $102 with 4 mg-ondansetron, $3.0 with 0.625 mg-droperidol, and $2.3 with 1.25 mg-droperidol.
In all the incremental analyses, the difference between ondansetron and both the droperidol-based therapies reached statistical significance.
Droperidol 1.25 mg represented the most cost-effective treatment in terms of all of the outcome measures, as it dominated the remaining therapies (more effective and less costly).
Authors' conclusions Anti-emetic therapies were highly cost-effective for the prevention of post-operative nausea and vomiting (PONV) in ambulatory patients. Droperidol 1.25 mg proved to be the most cost-effective therapy.
CRD COMMENTARY - Selection of comparators The rationale for the choice of the comparators was clear. Placebo was selected since the objective of the study was to assess the active value of the three anti-emetic therapies. You should assess the relevance of each anti-emetic therapy to your own setting.
Validity of estimate of measure of effectiveness The internal validity of the effectiveness analysis was likely to be high due to the randomised, double-blind, multicentre design of the study. The authors stated that the study groups were comparable. Power calculations and the results of the patients' assessment were not reported, since the main details of the analysis were published in a different paper (see Other Publications of Related Interest).
Validity of estimate of measure of benefit The benefit measures used in the economic analysis were derived from the effectiveness analysis. All of them appear to have been appropriate to estimating the impact of the therapies on patient health. Valuations in terms of the quality of life would also have been informative.
Validity of estimate of costs All the categories of costs relevant to the perspective adopted in the study appear to have been included in the analysis. The unit costs and the quantities of resources were reported separately. Information on the costs and the quantities was obtained from actual data. However, no price year was reported and statistical analyses on the quantities were not carried out. An incremental analysis of the costs was performed. Sensitivity analyses on the costs were not conducted.
Other issues The authors made comparisons of their findings with those from other studies. They did not, however, address the issue of the generalisability of the results to other settings. In addition, sensitivity analyses were not carried out. These factors limit the external validity of the analysis. However, the unit costs and the quantities of resources used were reported separately, which is a good feature of the analysis.
Implications of the study Prophylactic therapies should be used for the prevention of post-operative nausea and vomiting episodes among high-risk ambulatory surgical patients.
Source of funding Supported in part by a grant from Glaxo Wellcome Inc., Research Triangle Park (NC), USA.
Bibliographic details Hill R P, Lubarsky D A, Phillips-Bute B, Fortney J T, Creed M R, Glass P S, Gan T J. Cost-effectiveness of prophylactic antiemetic therapy with ondansetron, droperidol, or placebo. Anesthesiology 2000; 92(4): 958-967 Other publications of related interest Fortney JT, Gan TJ, Graczyk S, Wetchler B, Melson T, Khalil S, et al. A comparison of the efficacy, safety, and patient satisfaction of ondansetron versus droperidol as antiemetics for elective outpatient surgical procedures. S3A-409 and S3A-410 Study Groups. Anesthesia and Analgesia 1998;86:731-8.
Indexing Status Subject indexing assigned by NLM MeSH Adolescent; Adult; Aged; Antiemetics /adverse effects /economics /therapeutic use; Cost-Benefit Analysis; Double-Blind Method; Droperidol /adverse effects /economics /therapeutic use; Female; Humans; Male; Middle Aged; Ondansetron /adverse effects /economics /therapeutic use; Postoperative Nausea and Vomiting /economics /prevention & control AccessionNumber 22000000732 Date bibliographic record published 31/12/2002 Date abstract record published 31/12/2002 |
|
|
|