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Health technology assessment

Health technology assessment of Transcatether aortic valve implantation (TAVI) as treatment of patients with severe aortic stenosis and intermediate surgical risk – Part 2. Health economic evaluation

  • Year: 2019
  • By: Norwegian Institute of Public Health
  • Authors Fagerlund BC, Stoinska-Schneider A, Lauvrak V, Juvet LK, Robberstad B.
  • ISBN (digital): 978-82-8406-015-6
Forside_TAVI ENG.jpg

We were to commissioned perform a health technology assessment evaluating Transcatheter aortic valve implantation (TAVI) as treatment for patients with severe aortic stenosis and intermediate surgical risk.

Downloadable as PDF. In English. Norwegian summary.

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Key message

The National System for Managed Introduction of New Health Technologies within the Specialist Health Service in Norway (Nye Metoder) commissioned the Norwegian Institute of Public Health (NIPH) to perform a health technology assessment evaluating Transcatheter aortic valve implantation (TAVI) as treatment for patients with severe aortic stenosis and intermediate surgical risk. The effect and safety aspects of the intervention are addressed by the rapid assessment published by EUnetHTA in December 2018 (Part 1), co-authored by NIPH.

The aim of this report on health economic evaluation was to assess the cost-effectiveness of TAVI for patients with severe aortic stenosis and intermediate surgical risk compared with open surgery against the priority criteria applicable in Norway.

The key results are:

  • The cost-utility analysis indicated that TAVI was slightly more effective (in terms of 0.07 quality-adjusted life-years (QALY) gain) and more costly (in terms of incremental costs of 71 000 Norwegian kroner) than the open surgery. These results were robust to variations in assumption about the time perspective.
  • The incremental cost-effectivness ratio (ICER) was about 1.04 million Norwegian kroner per QALY in analysis with two-years perspective, falling to about 800 000 kroner per QALY in life time perspective.
  • The results of sensitivity analysis of our model analysis showed that cost parameters related to the TAVI procedure had the greatest impact on the results (ICER).
  • We have performed an analysis quantifying the severity criterion by calculating absolute shortfall for patients with severe aortic stenosis and intermediate surgical risk. The results show the absolute shortfall of 3.6 QALYs.
  • The budget impact analysis based on the results of our cost-effectiveness analysis, and some conservative assumptions about expansion in the use of TAVI indicates that the incremental annual total cost of this expansion will reach 32.5 million Norwegian kroner in the course of five years.  

Summary

Background

Transcatheter aortic valve implantation (TAVI), is the replacement of the aortic valve with a bioprosthesis delivered with use of a catheter in patients with severe aortic stenosis. TAVI has been in use in Norwegian hospitals for nearly a decade. Until recently the use was restricted to treatment of patients with severe symptomatic aortic valve stenosis that were inoperable or at high surgical risk of mortality or of complications from open surgery.

The National System for Managed Introduction of New Health Technologies within the Specialist Health Service in Norway (Nye Metoder) commissioned the National Institute of Public Health (NIPH) to perform a health technology assessment evaluating TAVI as treatment for patients with severe aortic stenosis and intermediate surgical risk. The effect and safety aspects of the intervention were assessed in the rapid assessment published by EUnetHTA in December 2018, which NIPH co-authored. The present report addresses health economics and organisational aspects of the intervention in the Norwegian settings.

Objective

The aim of this report is to assess the cost-effectiveness and budget impact of TAVI for patients with severe aortic stenosis and intermediate surgical risk compared with open surgery, and evaluate the intervention against the priority criteria (benefit, resource use and severity) applicable in Norway.

Methods

We performed a cost-utility analysis (CUA) comparing TAVI with open surgery, where all relevant cost and health outcomes related to both procedures were accounted for.  The relevant costs were expressed in 2018 Norwegian kroner (NOK), and effects in quality-adjusted life-years (QALYs). The results were expressed as mean incremental cost-effectiveness ratio (ICER). The Markov model was developed and analysed in TreeAge Pro ® 2018. The uncertainty in model parameters were handled by performing probabilistic sensitivity analyses (PSA). The analyses were performed from the healthcare perspective. Both costs and effects were discounted using an annual discount rate of 4%.

In accordance with the Government White Paper about priority setting, (Meld. St. 34 2015–2016)(2), and its recommendations related to quantification of the severity criterion, we estimated absolute shortfall for patients with severe aorta stenosis and intermediate surgical risk.

Premised on assumptions based on registry data about adoption rates for TAVI as well as cost data derived from the Markov model, we calculated likely budgetary consequences of introduction of TAVI as a routine treatment for patients with severe aortic stenosis and intermediate surgical risk.

Results

The cost-utility analysis indicated that TAVI was slightly more effective (incremental effectiveness: 0.07 QALYs) and more costly (incremental costs: 71 000 Norwegian kroner) than the open surgery.

The incremental cost-effectiveness ratio (ICER) was about 1.04 million Norwegian kroner per QALY in analysis with two-years perspective, falling to about 800 000 kroner per QALY in life time perspective. The results of sensitivity analysis of our model analysis showed that cost parameters related to the TAVI procedure had the greatest impact on the results.

The calculated absolute shortfall for patients with severe aorta stenosis and intermediate surgical risk is equal to 3.6 QALYs.  The budget impact analysis based on the results of the cost-effectiveness analysis, and some conservative assumptions about expansion in the use of TAVI indicates that the incremental annual total cost of this expansion will reach 32.5 million Norwegian kroner in the course of five years.

Discussion

The cost-utility analyses were based on the clinical data from a single randomized control multicentre trial (PARTNER 2A). For a number of outcomes, it was not possible to use pooled data from both studies included in EUnetHTA’s relative effectiveness assessment, due to significant heterogeneity. Moreover, type of technology used in the included trial is in accordance with technology used most often in Norwegian clinical practice.

We used two-year perspective in the base case scenario in accordance with the time perspective for the efficacy data that informed the model. Mortality rates as well as valve function at two years follow-up were not significantly different between the treatment options. In addition, most of the complications occurred in the acute phase following aortic valve implantation and their rates were falling with time. We considered the two-year perspective sufficient for capturing all relevant differences in outcomes. A separate scenario analysis, with lifetime time perspective showed similar results with ICER of about 800 000 kroner per QALY.

The results should be interpreted with caution as long-term effects on survival, complications, prostheses’ longevity and need for future re-intervention remain to be established and documented.

Conclusion

The results of our cost-utility analysis indicate that TAVI for patients with aortic stenosis and intermediate surgical risk compared with open surgery offers modest health gains (incremental effectiveness: 0.07 QALYs), at higher costs (incremental costs: 71 000 Norwegian kroner). The calculated incremental cost-effectiveness ratio is equal to 1.04 million Norwegian kroner per QALY gained in the base case scenario.

The calculated absolute shortfall for patients with severe aortic stenosis and intermediate surgical risk receiving standard treatment is equal to 3.6 QALYs, categorising these patients into severity class 1, which is the least severe of the six classes suggested by the Magnussen group.

These findings can help decision makers appraise the intervention against the official priority setting criteria in health care sector applicable in Norway.