Cost-benefit analysis of first-generation antihistamines in the treatment of allergic rhinitis Sullivan P W, Follin S L, Nichol M B

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1 Cost-benefit analysis of first-generation antihistamines in the treatment of allergic rhinitis Sullivan P W, Follin S L, Nichol M B 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 first-generation antihistamines (FGAs) in the treatment of allergic rhinitis in adults. Type of intervention Primary prevention. Economic study type Cost-benefit analysis. Study population The study population comprised a hypothetical cohort of adults with allergic rhinitis in the USA. Setting The setting was primary care (drug prescription). The economic study was carried out in the USA. Dates to which data relate The benefits associated with FGAs were estimated using willingness-to-pay (WTP) questionnaires at 2001 values. Estimates of the incidence of sedation and the economic cost of lost productivity caused by FGAs were derived from a review of the literature. The studies selected were published up to The costs associated with sedation were based on data from the National Highway Traffic Safety Administration (NHTSA), with injuries classified by their level of threat to life according to the Maximum Abbreviated Injury Scale (MAIS) score. The price year for the costs and benefits was Source of effectiveness data The benefits associated with FGAs were estimated using a WTP framework. The questionnaire was designed from a global perspective in order to incorporate the impact of allergic rhinitis treatment on all potential intangible benefits. Modelling A decision tree model was used to model the benefits and costs associated with the use of FGAs. A probabilistic sensitivity analysis was conducted using Bayesian second-order Monte Carlo simulation. Both the costs and benefits were discounted at a rate of 3%. Outcomes assessed in the review The societal benefits associated with using FGAs for the treatment of allergic rhinitis were quantified using the WTP framework. The following parameters were derived from the literature: Page: 1 / 5

2 the prevalence of allergic rhinitis; the incidence of injuries and fatalities due to FGA-associated sedation (estimated separately for motor vehicle and nonmotor vehicle accidents); and the risk of experiencing occupational, home and public unintentional injuries. Study designs and other criteria for inclusion in the review Sources searched to identify primary studies Not reported. Criteria used to ensure the validity of primary studies Methods used to judge relevance and validity, and for extracting data Number of primary studies included Approximately 24 studies were included in the review. Methods of combining primary studies The results of the individual primary studies were directly combined in the decision analysis tree. Investigation of differences between primary studies Results of the review The values of the most important outcome drivers were as follows: the prevalence of allergic rhinitis in the USA was 40 million people; the incidence of sedation caused by FGAs was 17% on average (range: 10-25); the baseline risk of experiencing an occupational injury associated with the use of FGAs was a 50% increase (odds ratio 1.5). The lost productivity for patients taking FGAs was 1.2 days per patient for the base-case analysis. Measure of benefits used in the economic analysis Monetary benefits were used as the main outcome measure in the economic analysis. The WTP framework was designed using a global perspective in order to incorporate the impact of allergic rhinitis treatment on intangible benefits, such as quality of life, future health care costs avoided and usual activities (e.g. productivity output). Direct costs Page: 2 / 5

3 The quantities and the costs were analysed separately. The total cost of FGA-associated sedation was estimated using the human capital approach for lost productivity and the direct and indirect cost of unintentional injuries and fatalities (including motor vehicle, occupational, public and home). The weighted average cost to society of the average collision ($8,028) included the following main direct costs: medical care ($1,161) and emergency medical services ($50). The cost of the average non-motor vehicle injury or fatality ($18,254) included the following main direct costs: medical expenses ($3,961) and administrative expenses ($1,789). Part of these direct costs would be supported by the patients themselves, depending on whether they are entitled to receive public assistance through Medicare or Medicaid. All the costs were discounted at an annual rate of 3%. The price year was Statistical analysis of costs The costs were analysed stochastically, and probability distributions were assigned to all estimates. The utilisation rates were assumed to follow a beta distribution, while the mean costs were expected to follow a gamma distribution. Baseline values and ranges were tabulated (tables I to IV) in the original paper. Indirect Costs The weighted average cost to society of the average collision ($8,028) included the following main indirect costs: lost market productivity ($2,171), lost household productivity ($714), insurance administration ($533) and property damage ($2,009). The cost of the average non-motor vehicle injury or fatality ($18,254) included the following main indirect costs: wage and productivity losses ($10,839) and employer costs ($570). The indirect costs were discounted at an annual rate of 3%. The price year was Currency US dollars ($). Sensitivity analysis A probabilistic sensitivity analysis was conducted using Bayesian second-order Monte Carlo simulation (10,000 simulations). In addition, a univariate sensitivity analysis was carried out to identify which variables had the greatest effect on the model results. Each of the input parameters was varied by 15%. Estimated benefits used in the economic analysis The results suggested that allergic rhinitis patients would be willing to pay approximately $28.35 per week for complete symptom resolution without adverse effects. Based on current use (16 weeks), the total societal benefit associated with using FGAs for the treatment of allergic rhinitis was $7.7 billion (95% credible interval: ). Cost results Based on current use (16 weeks), the total societal cost of FGAs was $11.95 billion (95% credible interval: ). The total societal cost of purchasing FGA was $697 million, but the main cost driver was the societal cost of FGAassociated sedation ($11.3 billion). The cost of side effects was not included. Synthesis of costs and benefits In the base-case analysis, the societal net benefit of using FGAs for the treatment of allergic rhinitis in the USA in 2001 was -$4.2 billion (95% credible interval: ). Page: 3 / 5

4 The results of the sensitivity analyses suggested that variability in the odds of both motor vehicle and non-motor vehicle injury had a significant effect on the model results. The results of a threshold analysis suggested that if taking FGAs had no effect on non-motor vehicle accidents, the net societal benefit would be slightly positive. Authors' conclusions It is possible that the costs associated with sedation exceed the benefits of first-generation antihistamine (FGA) use in the USA. CRD COMMENTARY - Selection of comparators The authors did not provide any justification for the choice of the comparator. The option of second-generation antihistamines instead of the "do nothing" option might have been more realistic and/or could have provided important information for decision-making. You should decide whether it represents a valid comparator in your own setting. Validity of estimate of measure of effectiveness The authors did not state that a systematic review of the literature had been undertaken. In addition, they could have better justified their assumptions with reference to the medical literature. All estimates were investigated in the sensitivity analysis, using ranges that were justified and appear to have been appropriate. Given the limited reporting on the selection of parameters from the literature, it was difficult to ascertain whether the best available evidence was used to populate the decision tree. Validity of estimate of measure of benefit Monetary benefits were used as the main outcome measure as this was a cost-benefit analysis. It would have been useful had the questionnaire been discussed in more detail or presented as an appendix to the paper. Validity of estimate of costs The authors explicitly stated the perspective adopted in the study. As such, it appears that all the relevant cost categories have been included in the analysis. The costs were treated stochastically and appropriate univariate sensitivity analyses were carried out. Discounting was relevant and was conducted on both the costs and benefits. The price year was reported, which will aid future reflation exercises. Other issues The main limitations of the study were appropriately presented in the discussion section. A breakdown of medical care category costs for motor vehicle and non-motor vehicle injury or fatality should have been presented. The role of indirect costs as the main drivers of the cost-difference between FGAs use and no treatment should have been discussed. Implications of the study The authors stated that the study provides compelling evidence of the potential economic burden of sedation associated with FGA use, but did not suggest any specific policy implications or applications. The authors suggested that further research should focus on the relative costs and benefits of FGAs compared with other alternative treatment options, such as second-generation antihistamines. Source of funding None stated. Page: 4 / 5

5 Powered by TCPDF ( Bibliographic details Sullivan P W, Follin S L, Nichol M B. Cost-benefit analysis of first-generation antihistamines in the treatment of allergic rhinitis. PharmacoEconomics 2004; 22(14): PubMedID Indexing Status Subject indexing assigned by NLM MeSH Accidents /economics /statistics & numerical data; Attitude to Health; Bayes Theorem; Cost of Illness; Cost-Benefit Analysis; Decision Support Techniques; Female; Histamine H1 Antagonists /adverse effects /economics /therapeutic use; Humans; Male; Models, Economic; Monte Carlo Method; Rhinitis, Allergic, Perennial /drug therapy /economics; Rhinitis, Allergic, Seasonal /drug therapy /economics; Surveys and Questionnaires; United States AccessionNumber Date bibliographic record published 31/12/2005 Date abstract record published 31/12/2005 Page: 5 / 5