https://orcid.org/0000-0002-4881-720X
Introduction
Aortic stenosis (AS) has been established as the most prevalent kind of valvular heart disease and its classic manifestations are angina pectoris, heart failure and syncope. Usually, systolic hypertension is also recorded in patients presenting with AS.
AS has been associated with a steady incidence increase, in par with an ageing population worldwide. In symptomatic patients, the replacement of the valve is the only viable option, since medication alone was associated with suboptimal outcomes and poor prognosisCitation1.
Even with the advancements in surgical aortic valve replacement (SAVR) technology, a significant portion of patients remain ineligible for surgery because such a procedure of this magnitude would likely put some patients at undue risk of death. This patient cohort includes individuals with coexisting medical conditions, individuals unable to undergo cardiopulmonary bypass owing to aortic calcification and other severe comorbidities. This rate corresponds to more than 30% of all AS cases.
In this inoperable patient cohort, transcatheter aortic valve implantation (TAVI) has significantly reformed the aortic replacement context since its first use in 2002 by Cribier et al.Citation2 in an inoperable patient utilizing a balloon-expandable valve.
Consequently, in its advent, TAVI was predominantly positioned for inoperable patients. As more data were accumulated and more favorable clinical trial results were published, coupled with the elucidation of technical parameters, along with advances in the technical characteristics of the equipment and introduction of newer and better valves, its use was expanded to lower risk cohorts. Physicians were keen to perform a less-resourced demanding process, while from patient’s values and preferences perspective, the pain related to SAVR is a major concern, despite that in general, the literature of patients’ perceptions and attitudes pertinent to aortic stenosis management is of suboptimal quality and highly heterogenicCitation3.
Therefore, the accumulation of evidence, the better understanding of vascular features, the gain of technical expertise and the unmet medical need has expanded the operational focus from the inoperable and high-risk patients to the intermediate and low-risk patients.
While effectiveness was ascertained across the risk cohorts, the efficiency of TAVI was engulfed in controversy. TAVI comes at a substantial cost, driven by the product’s acquisition cost. Moreover, its economic evaluation has revealed an array of factors which can affect final economic outcomes.
The first economic evaluations focused on inoperable and high-risk patientsCitation4. As several systematic reviews have demonstrated, despite the substantial variability both cross- and even within the same country, the economic evaluations in high-risk patients are more consistent in demonstrating efficiency compared to the inoperable cohort. In the intermediate risk setting, some studies reported dominance of TAVI, while in the low-risk, the results were consistently favorable for the TAVI. A confounding variable was the publication year since a correlation was noted between publication year and better efficiency, a finding that can be attributed to the use of newer generation valves, improvement in the technical aspects and access route.
TAVI in Japan
Japan, in line with other developed countries faces the same pattern of AS increase, owing to an ageing population. In addition to the higher risk cohorts, in March 2021 the implantation of SAPIENS 3 in low-risk patients was approved by the Japanese Ministry of Health, Labor and Welfare. Therefore, the need to assess its efficiency in intermediate and low-risk patients is imperative for an informed decision-making process.
Economic evaluation of SAPIEN 3 in Japan
In current issue of the Journal of Medical economics, Kobayashi et al. assessed the cost-effectiveness of SAPIEN 3 from a Japanese perspective. The Authors proposed a Markov model, with clinical and utility data mined from systematic literature review. The model employed a lifetime horizon, and the discount was set at 2%Citation5. Of importance is that the starting age of patients in the Markov Model was 83 years old.
The Authors concluded that in the intermediate-risk cohort, TAVI dominated SAVR, while in the low-risk cohort, the ICER for TAVI was estimated at ¥750,417/QALY. Given that the willingness-to-pay threshold in Japan is ¥5 million/QALY, TAVI qualifies as a highly cost-effective modality.
The results of the sensitivity analysis deviate slightly between the two cohorts. In the intermediate risk cohort, results were sensitive to the cost of Tavi, one-year mortality and cost of SAVR. In the low-risk cohort the cost of Tavi was the most important variable, while the cost of SAVR was second and the SAVR procedure fee was ranked as third.
Discussion
In the intermediate risk-cohort, this study has not confirmed previous reports hailing from Japan, such as the study by Kodera et al.Citation6 Kodera’s study was also performed on a Japanese intermediate risk population and reported a non-cost effective profile of the TAVI. It seems that the differences were attributed to increased SAVR cost and reduced TAVI health gains, in terms of QALY. Moreover, the time horizon was set by Kodera at a 10-year horizon, which probably justifies the increased SAVR costs. Nevertheless, a key differentiating factor is the assessment of SAPIEN XT by Kodera, while the current study examined a newer generation valve, namely SAPIEN 3.
In the low-risk patient, this study bears a close resemblance with an array of studies who reported cost-efficiency of TAVI vs SAVR.
Policy implications
The existing body annotates that TAVI is cost-effective both in intermediate and low-risk patients, while the current study proceeds to outline that in intermediate-risk patients TAVI dominates SAVR. This finding is ascribed to the introduction of newer generation TAVI, along with a better understanding of this emerging technology and the underlying physiology. Nevertheless, we should underline the median age of patients, which was 83. In this perspective, the lifetime horizon of the study may be obsolete, given patients' life expectancy.
Moreover, policy-makers should cope with the budget impact of TAVI. In addition, the fragmentation of health systems and the lack of a holistic financial approach perpetuates to increased TAVI acquisition costs, which burdens payers since it’s usually reimbursed in addition to the DRG cost, while the savings are recorded on other health care centers, such as shorter hospital stays and less need for Intensive Coronary Unit stay (ICU), thus benefiting hospitals. This silo mentality minimizes any incentives for further penetration of efficient technologies, whose added value is going to be redeemed in other health care sectors.
Finally, the debate of TAVI vs SAVR should be positioned in the younger patients, whose primary decision must be capitalized on the longevity of TAVI vs SAVR, especially contemplating the new surgical valves, which-at least in vitro-have demonstrated a substantial longevity, the acknowledged Achilles’ heel of TAVI valvesCitation7.
Transparency
Declaration of financial/other relationships
No potential conflict of interest was reported by the author.
Reviewer disclosures
A reviewer on this manuscript has disclosed that they held a series of contracts with the manufacturer of the Sapien 3 TAVI (Edwards LifeSciences) between 2010 and 2016. Peer reviewers on this manuscript have no other relevant financial relationships or otherwise to disclose.
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References
- Cribier A, Eltchaninoff H, Bash A, et al. Percutaneous transcatheter implantation of an aortic valve prosthesis for calcific aortic stenosis: first human case description. Circulation. 2002;106(24):3006–3008. doi: 10.1161/01.cir.0000047200.36165.b8.
- Bevan GH, Zidar DA, Josephson RA, et al. Mortality due to aortic stenosis in the United States, 2008–2017. JAMA. 2019;321(22):2236–2238. doi: 10.1001/jama.2019.6292.
- Heen AF, Lytvyn L, Shapiro M, et al. Patient values and preferences on valve replacement for aortic stenosis: a systematic review. Heart. 2021;107(16):1289–1295. doi: 10.1136/heartjnl-2020-318334.
- Petrou P. The economics of TAVI: a systematic review. Int J Cardiol Heart Vasc. 2023;44:101173. doi: 10.1016/j.ijcha.2023.101173.
- Kobayashi J, Baron SJ, Takagi K, et al. Cost-effectiveness analysis of transcatheter aortic valve implantation in aortic stenosis patients at low- and intermediate-surgical risk in Japan. J Med Econ. 2024;27(1):697–707. doi: 10.1080/13696998.2024.2346397.
- Kodera S, Kiyosue A, Ando J, et al. Cost effectiveness of transcatheter aortic valve implantation in patients with aortic stenosis in Japan. J Cardiol. 2018;71(3):223–229. doi: 10.1016/j.jjcc.2017.10.008.
- Sadri V, Trusty PM, Madukauwa-David ID, et al. Long-term durability of a new surgical aortic valve: a 1 billion cycle in vitro study. JTCVS Open. 2021;9:59–69. doi: 10.1016/j.xjon.2021.10.056.