Cost-effectiveness of transcatheter aortic valve implantation (TAVI) for aortic stenosis in patients who are high risk or contraindicated for surgery: a model-based economic evaluation.

BACKGROUND: Calcific aortic stenosis (AS) is a common valvular heart disease. Patients with severe symptomatic AS typically survive less than 3 years. In such patients, intervention with surgical aortic valve replacement (SAVR) may increase survival. However, in some patients SAVR is associated with a high operative risk and medical management is considered appropriate. Transcatheter aortic valve implantation (TAVI) is a relatively recent technique to avoid the invasiveness of open surgery. This procedure has been used for the treatment of patients with severe AS who are unsuitable for SAVR (because it is too high risk and/or for other reasons such as suffering from porcelain aorta) and is increasingly being considered for other patients.
OBJECTIVES: To determine the cost-effectiveness of TAVI being made available for patients who are high risk or contraindicated for SAVR through a review of existing economic evaluations and development of a model. DATA SOURCES AND REVIEW
METHODS: Bibliographic databases [MEDLINE, EMBASE, The Cochrane Library, Health Technology Assessment (HTA), Database of Abstracts of Reviews of Effects (DARE) and NHS Economic Evaluation Database (EED), Centre for Reviews and Dissemination HTA, DARE and NHS EED], guideline resources, current trials registers, websites/grey literature and manufacturers' websites, and consultation with clinical experts were used to identify studies for the review and information for the model. Databases were searched from 2007 to November 2010. A model was built to assess the cost-effectiveness of TAVI separately in patients suitable and unsuitable for SAVR, together with overall results for the effect of making TAVI available. Substantial deterministic sensitivity analysis was carried out together with probabilistic sensitivity analysis.
RESULTS: No fully published cost-effectiveness studies were found. Modelling patients not suitable for SAVR, the base-case results show TAVI as more costly but more effective than medical management, with an incremental cost-effectiveness ratio (ICER) of £12,900 per quality-adjusted life-year (QALY). The ICER was below £20,000 per QALY for over 99% of model runs in the probabilistic sensitivity analysis. For patients suitable for SAVR, the comparator with TAVI is a mixture of SAVR and medical management. TAVI is both more costly and less effective than this comparator assuming that most patients would receive SAVR in the absence of TAVI. This is robust to a number of assumption changes about the effects of treatment, but sensitive to assumptions about the proportion of patients receiving SAVR in the comparator. If the use of TAVI is extended to include more patients suitable for SAVR, the overall results from the model become less favourable for TAVI. LIMITATIONS: The modelling involves extrapolation of short-term data and the comparison between TAVI and SAVR is not based on randomised data. More trial data on the latter have been published since the modelling was undertaken.
CONCLUSIONS: The results for TAVI compared with medical management in patients unsuitable for surgery are reasonably robust and suggest that TAVI is likely to be cost-effective. For patients suitable for SAVR, TAVI could be both more costly and less effective than SAVR. The overall results suggest that, if a very substantial majority of TAVI patients are those unsuitable for SAVR, the cost-effectiveness of a broad policy of introducing TAVI may fall below £20,000 per QALY. Future work required includes the incorporation of new data made available after completion of this work. FUNDING: The National Institute for Health Research Health Technology Assessment programme.