Economic evaluation of antibacterials in the treatment of acute sinusitis Laurier C, Lachaine J, Ducharme M

Transcription

1 Economic evaluation of antibacterials in the treatment of acute sinusitis Laurier C, Lachaine J, Ducharme M 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 Oral antibacterial regimens for the treatment of ambulatory patients with acute sinusitis. No single regimen was identified as the intervention. Type of intervention Treatment. Economic study type Cost-effectiveness analysis. Study population Adults treated for acute sinusitis. Setting Primary care. The economic study was carried out in the Canadian province of Quebec. Dates to which data relate Effectiveness data and resource use data on medications were collected from studies previously published between January 1986 and July The date to which other resource use data relate was not specified. The price year was Source of effectiveness data Review of previously published studies. Modelling A decision tree (TreeAge Software Inc.) was used to model costs and outcomes associated with alternate antibacterial regimens. The decision tree, which was validated by expert opinion, considered the episode of care from the decision to initiate a given antibacterial treatment until the end of that initial course of treatment or the end of the subsequent course of treatment when needed. Outcomes assessed in the review The review assessed only one outcome: the proportion of patients showing resolution or improvement of their symptoms. The proportion of those who discontinued treatment for adverse events was also reported, although no summary statistic was calculated. Page: 1 / 5

2 Study designs and other criteria for inclusion in the review Clinical trial data published in either English or French between 1986 to 1996 were included in the review. All studies included at least one of the comparator antibacterials. Studies on adult patients with acute sinusitis, or acute exacerbations of chronic sinusitis were included; studies on chronic sinusitis or studies that did not provide separate results for patients with chronic and acute sinusitis were not included. Studies performed in specific subgroups of patients or studies on a specific pathogen were discarded. Studies that did not separate results for sinusitis from results obtained for other upper respiratory tract infections were excluded. Studies were rejected if they did not report their results as a proportion of patients whose condition was cured or significantly improved. Studies were either open or blinded and included those of comparative and non-comparative design. Sources searched to identify primary studies Studies were identified through searching Medline and Current Contents using sinusitis as a key word. Criteria used to ensure the validity of primary studies While the authors acknowledged that the internal validity of double-blind trials is theoretically better, open and single blind trials were also included in the review in order to provide the best estimate of success. Methods used to judge relevance and validity, and for extracting data Two individuals working separately and using a standardised approach reviewed studies. Individual data from the original studies were used. Number of primary studies included 29 studies were included in the review, of which 23 were RCTS, 4 were non-comparative trials and 2 were open-label comparative trials. Methods of combining primary studies For the base-case analysis, studies were grouped according to total treatment dose for each antibacterial and then pooled. In an alternate analysis, results from all trials pertaining to a given antibacterial were pooled irrespective of dosage used. For a given dosage group, the proportion of patients with resolution or significant improvement was determined as the average of the proportions reported in each trial, weighted by the number of patients evaluated in that trial. Investigation of differences between primary studies The results in terms of efficacy were considered to be similar for all types of trial. Results of the review Average efficacy of initial plus subsequent treatment varied between for the amoxicillin/clavulanate regimen and for both the cefaclor intermediate dose regimen and the clarithromycin low dose regimen. Average efficacy at the end of initial treatment varied between for the cefaclor low dose regimen and for the clarithromycin low dose regimen. Confidence intervals were not reported. Measure of benefits used in the economic analysis Clinical efficacy was used as the measure of benefit. Direct costs Quantities and costs were reported separately. The quantity/cost boundary adopted was that of the health service. Direct Page: 2 / 5

3 costs included the cost of follow up physician visits, diagnostic tests and medications (including the pharmacist's dispensing fee). Medications resource use data was derived from published trials. Remaining resource use estimates were based on expert opinion, consisting of a panel with 4 primary care physicians and one ENT specialist. The cost of a physician visit, pharmacist dispensing fees and the cost of (generic) medications were determined according to the Regie de l'assurance Maladie du Quebec (RAMQ) schedule. Costs related to diagnostic tests were based on prices charged to the RAMQ by private laboratories. The price year was Since the costing period was under 12 months, discounting was not applicable. Statistical analysis of costs Not applicable. Indirect Costs Not included. Currency Canadian dollars (Can$). Sensitivity analysis Univariate sensitivity analyses were conducted. The parameters varied included the probability of success for the subsequent treatment, the probability of a visit when initial treatment fails, the probability of a visit when initial treatment has to be discontinued due to adverse effects and the probability of a routine follow-up visit when initial treatment is successful. Variations in certain costs were also investigated, including the cost of failure with subsequent treatment, the cost of a medical visit and the cost of diagnostic tests. Cost-effectiveness estimates were also carried out using,conservative- and,optimistic- estimates of efficacy; mean efficacy was varied by one standard deviation for these analyses. Estimated benefits used in the economic analysis See "Effectiveness results" above. Cost results Total per-patient costs varied between Can$69 for the amoxicillin regimen and Can$126 for the clarithromycin highdose regimen. Synthesis of costs and benefits For the case of initial plus subsequent treatment, the amoxicillin regimen cost Can$70 per success, compared with the second most cost-effective comparator, low-dose clarithromycin, which cost Can$82, giving an incremental costeffectiveness ratio of low-dose clarithromycin over amoxicillin of Can$2,131. If differences in efficacy were considered to be clinically insignificant, then a cost-minimization situation would prevail and amoxicillin constitutes the most 'attractive' regimen followed by low-dose clarithromycin and azithromycin. For the case of initial treatment only, the amoxicillin regimen cost Can$77 per success, compared with the second most cost-effective comparator, low-dose clarithromycin, which cost Can$86, giving an incremental cost-effectiveness ratio of low-dose clarithromycin over amoxicillin of Can$262. The authors state that sensitivity analyses showed these results to be robust, with the relative positions of the dominant regimens remaining stable in all cases. Authors' conclusions This study confirms the place of amoxicillin as a first choice agent for acute sinusitis, with low-dose clarithromycin and azithromycin as second choices. Page: 3 / 5

4 CRD COMMENTARY - Selection of comparators rationale for the choice of the comparator was clear. You, as a user of this database, should consider whether these antibacterial regimens for the treatment of acute sinusitis are widely used in your own setting. Validity of estimate of measure of benefit h any meta-analysis of previously published studies, the abbreviated evaluation period of the studies and the lack of certainty of long-term outcomes may limit the validity of the results. Further limitations may arise from the expected increased compliance, the increased rate in reporting adverse drug events and the potential for unrepresentative study populations. The results were based on a limited number of trials in which some patients were lost to follow-up or excluded for non-conformity with the protocol. Therefore, it is likely that these trials overestimate the impact of antibacterial therapy. Moreover, the dosage and duration of treatment used in the clinical trials could be different from those prevailing in current practice. Sensitivity analysis was performed on the estimates of efficacy. However, these were varied within a narrower range than the 95% confidence intervals surrounding the means. The reliability of the cost-effectiveness ratios and the implications for cost-effective prescribing are therefore uncertain. Validity of estimate of costs tain costs and quantities were reported separately, but the absence of some unit costs (such as the cost of a physician visit) does not permit the costing to be reworked for other settings. Some estimates of resource consumption were based on assumptions made by a small panel of physicians, who may have been unrepresentative. Although the assumptions were explored by a univariate sensitivity analysis, the implication for cost-effectiveness of 'best case' and 'worst case' scenarios was not considered. It is unclear if data on adverse events was pooled from trial data and whether this was included in the costing process. Other issues issue of generalisability of the results to other settings or countries was not addressed. Implications of the study A prospective study that measures resource use would give a more accurate indication of the costs of these treatment regimens. Source of funding Partly funded by Abbott Canada. Bibliographic details Laurier C, Lachaine J, Ducharme M. Economic evaluation of antibacterials in the treatment of acute sinusitis. PharmacoEconomics 1999; 15(1): PubMedID Other publications of related interest 1. Pichichero M E, Cohen R. Shortened course of antibiotic therapy for acute otitis media, sinusitis and tonsillopharyngitis. Pediatric Infectious Disease Journal 1997;16(7): Quenzer R W, Pettit K G, Arnold R J G, Kaniecki D J. Pharmacoeconomic analysis of selected antibiotics in lower respiratory tract infection. American Journal of Managed Care 1997;3(7): Page: 4 / 5

5 Powered by TCPDF ( Indexing Status Subject indexing assigned by NLM MeSH Acute Disease; Adult; Anti-Infective Agents /economics /therapeutic use; Humans; Sinusitis /drug therapy /economics AccessionNumber Date bibliographic record published 31/01/2000 Date abstract record published 31/01/2000 Page: 5 / 5