OBJECTIVES: Cost-effectiveness analyses of new treatments for cardiovascular disease frequently require input parameters whose values are known with uncertainty due to limited data. The objective of this paper is to determine the extent to which published sensitivity analyses adhere to Health Technology Assessment (HTA) guidelines.
METHODS: We performed a systematic review of published cost-effectiveness analyses for an example drug treatment scenario, dual oral antiplatelet therapy compared with aspirin alone following acute coronary syndromes (ACS) and/or percutaneous coronary intervention (PCI). We searched for articles published in English from 1997 to mid-2008 in PubMed, Cochrane Collaboration, EMBASE, and Health Economic Evaluation Database (HEED). A total of 216 articles were identifi ed: PubMed, 40; Cochrane, 27; EMBASE, 114; HEED, 35. Of these, 106 articles were unique, and 16 were included in this review; all selected articles compared clopidogrel plus aspirin versus aspirin alone for patients with ACS and planned PCI. We created evidence tables to show the sensitivity of the cost-effectiveness estimates to changes in the input parameter values, as well as the data sources used for the reference-case and alternative estimates for different input parameter values. We also examined the extent to which the sensitivity analyses adhered to HTA guidelines.
RESULTS: Cost-effectiveness ratios were most sensitive to changes in the efficacy of dual antiplatelet therapy and reference- case model assumptions about costs beyond the trial period. Although the alternative values tested in the sensitivity analysis for some input parameters were based on observed ranges or distributions, the alternative values tested for many other input parameters were assumed without justification.
CONCLUSIONS: The sensitivity analyses of the cost-effectiveness studies of dual oral antiplatelet therapy were not fully adherent with HTA guidelines. In particular, long-term costs and benefits were not always included in the reference case and justification of the alternative parameter values was not always provided.
