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Economic evaluation of celecoxib, a new cyclo-oxygenase 2 specific inhibitor, in Switzerland |
Chancellor J V M, Hunsche E, de Cruz E, Sarasin F P |
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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 The use of celecoxib (a cyclo-oxygenase 2 (COX-2) inhibitor) in the treatment of arthritis patients in Switzerland.
Economic study type Cost-effectiveness analysis.
Study population A hypothetical population of 1000 patients with arthritis was studied. Both osteoarthritis (OA) and rheumatoid arthritis (RA) sufferers were considered on a 90%, 10% distribution, respectively.
Setting The setting was a hospital. The economic study was carried out in Switzerland.
Dates to which data relate Effectiveness data were collected from studies published between 1990 and 1999. Resource use data were collected from interviews with Swiss clinicians conducted during the first quarter of 1999. Cost data were taken from sources published in 1998 and 1999. The price year was not reported.
Source of effectiveness data Effectiveness data were derived from a literature review and authors' assumptions.
Modelling A six-month decision analytic model was used to determine the cost-effectiveness of the treatment alternatives. The model, COMET, was specific to the clinical area of interest, as described in a related publication.
Outcomes assessed in the review The review assessed gastrointestinal (GI) adverse events (instances of GI discomfort, symptomatic ulcer, anaemia with occult bleeding and serious hospitalised events) and risk scores. These data formed the principal input values used in the decision tree.
Study designs and other criteria for inclusion in the review Clinical trials and other studies were included in the review.
Sources searched to identify primary studies Criteria used to ensure the validity of primary studies Methods used to judge relevance and validity, and for extracting data Individual data from individual studies were used.
Number of primary studies included At least 18 studies were included.
Methods of combining primary studies The probabilities of GI adverse events were derived from pooled Kaplan-Meier estimates. Adverse event rates for NSAIDs administered with GPAs were derived from meta-analyses.
Investigation of differences between primary studies Results of the review The probability of misoprostol intolerance with NSAID plus misoprostol or diclofenac/misoprostol was 0.0233.
The probability of events in patients taking NSAIDs alone ranged from 0.0059 to 0.1454.
The relative risk of an event with celecoxib versus NSAIDs alone ranged from 0.2752 to 0.6465.
The relative risk of an event with NSAID plus PPI versus NSAIDs alone ranged from 0.3307 to 0.6403.
The relative risk of an event with NSAID plus H2RA versus NSAIDs alone ranged from 0.6518 to 0.9831.
The relative risk of an event with diclofenac/misoprostol versus NSAIDs alone ranged from 0.3610 to 1.2400.
The relative risk of an event with NSAID plus misoprostol versus NSAIDs alone ranged from 0.4010 to 1.1898.
The risk of developing a serious GI adverse event generally increased by 0.25% per risk category.
Methods used to derive estimates of effectiveness In order to augment this data required by the model estimates of effectiveness were also based on the authors' assumptions.
Estimates of effectiveness and key assumptions The mean time to an event of GI discomfort was estimated to be 13 days. Other types of adverse events were assumed to occur at 90 days. The authors assumed a patient distribution of 90% with osteoarthritis and 10% with rheumatoid arthritis. Patients received treatment with celecoxib for 6 months.
Measure of benefits used in the economic analysis The number of GI adverse events was used as the measure of benefits. Efficacy was assumed to be equal for all treatments.
Direct costs Direct costs were not discounted. This was appropriate as the time horizon analysed was less than 1 year. Quantities and costs were reported separately. Direct costs included costs of hospitalisations, consultations, medical procedures and tests, and drugs. The quantity/cost boundary adopted was that of a public health insurer. Resource utilisation assumptions were based on interviews with Swiss experts. The estimation of quantities and costs was based on actual data. Costs and quantities were obtained from published tariffs. The price year was not reported.
Statistical analysis of costs Costs were treated as point estimates and adjusted to stochastic form in the Monte Carlo simulation.
Indirect Costs Indirect costs were not included and this was appropriate for the perspective adopted. For a societal perspective, likely to be relevant for the studied population and to the UK NHS, productivity losses would need to be included.
Sensitivity analysis Multiple one-way sensitivity analyses and Monte Carlo simulations were conducted on the cost and effectiveness parameters.
Estimated benefits used in the economic analysis The authors reported GI events for each strategy and incremental events relative to celecoxib (shown in parentheses). These were:
Celecoxib, 115;
NSAIDs alone, 220 (105);
Diclofenac/misoprostol, 203(88);
NSAID + misoprostol, 202 (86);
NSAID + H2RA, 154 (38);
NSAID + PPI, 119 (4).
Cost results The authors reported cost estimates for each strategy and incremental costs relative to celecoxib (shown in parentheses). These were:
Celecoxib, which had the lowest costs, SFr435;
NSAIDs alone, SFf510 (SFr75);
Diclofenac/misoprostol, SFr522(SFr87);
NSAID + misoprostol, SFr1034 (SFr599);
NSAID + H2RA, SFr1201 (SFr766);
NSAID + PPI, SFr1415 (SFr980).
Synthesis of costs and benefits Celecoxib dominated NSAIDs alone. The Monte Carlo simulation indicated that the incremental cost-effectiveness ratios varied from -SFr1,229 to +SFr433 per event averted. Celecoxib was cost saving compared with NSAIDs alone in 95% of simulations. In all simulations, the cost per event averted fell below SFr440.
Authors' conclusions Celecoxib is the most cost-effective of the treatments considered for managing arthritis patients in Switzerland. A policy of switching patients from NSAIDs to celecoxib is predicted to be cost saving for public health insurers, while reducing the burden of iatrogenic GI side effects. Greater cost savings would be realised when patients are switched from NSAIDs used with gastroprotective agents.
CRD COMMENTARY - Selection of comparators A justification was given for the comparators used, namely that they represented current treatment alternatives. You, as a user of the database, should decide if these health technologies are relevant to your setting.
Validity of estimate of measure of effectiveness The authors undertook a literature review to derive estimates for the model, which seemed appropriate, although they did not state that a systematic review of the literature had been undertaken. Additional effectiveness estimates were, appropriately, based on authors' assumptions. The validity of the results was enhanced by sensitivity analyses to account for variability in the estimates. The authors noted that the four categories of GI event were not weighted according to their importance. Ideally, preference or utility weights should be applied.
Validity of estimate of measure of benefit The estimation of benefits was obtained directly from the effectiveness analysis.
Validity of estimate of costs Good features of the cost analysis were that all relevant direct cost categories were included, quantities and costs were reported separately and the validity of the cost results was enhanced by appropriate sensitivity analyses. However, the price year was not reported which would make reflation exercises in other settings problematic. Charges were not converted into costs and, hence, true opportunity costs were not estimated. The authors did not include indirect costs, such as lost wages due to time spent obtaining care, which are thought to be considerable. These aspects of the analysis tend to limit the generalisability of the cost results.
Other issues The authors did not make appropriate comparisons of their findings with those from other studies and did not address the issue of generalisability to other settings. The authors did not present their results selectively. The study considered Swiss patients with arthritis and this was reflected in the authors' conclusions. The authors noted that an estimate of cost per life year saved would be desirable. Moreover, they stated that if the tolerability profile of celecoxib resulted in improved effectiveness, the analysis may have underestimated the economic benefits.
Implications of the study Celecoxib is the most cost-effective option for the treatment of arthritis patients in Switzerland and is likely to yield outright savings for healthcare budgets if patients are switched from NSAID-based regimens.
Source of funding Supported by Pharmacia Corporation and Pfizer Inc.
Bibliographic details Chancellor J V M, Hunsche E, de Cruz E, Sarasin F P. Economic evaluation of celecoxib, a new cyclo-oxygenase 2 specific inhibitor, in Switzerland. PharmacoEconomics 2001; 19(Supplement 1): 59-75 Indexing Status Subject indexing assigned by NLM MeSH Anemia /chemically induced /economics; Anti-Inflammatory Agents, Non-Steroidal /adverse effects /economics /therapeutic use; Anti-Ulcer Agents /economics /therapeutic use; Arthritis /drug therapy; Celecoxib; Clinical Trials as Topic; Cost of Illness; Cost-Benefit Analysis; Cyclooxygenase Inhibitors /economics /therapeutic use; Decision Trees; Drug Therapy, Combination; Duodenal Ulcer /chemically induced /economics; Economics, Pharmaceutical; Humans; Probability; Pyrazoles; Sulfonamides /economics /therapeutic use; Switzerland AccessionNumber 22001008055 Date bibliographic record published 31/10/2001 Date abstract record published 31/10/2001 |
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