Demographics of severe valvular aortic stenosis in Singapore

Cost-effectiveness of transcatheter aortic valve implantation in patients with severe symptomatic aortic stenosis of intermediate surgical risk in Singapore

Objective

The objective was to assess the cost-effectiveness of transcatheter aortic valve implantation (TAVI) in patients with severe aortic stenosis with intermediate surgical risk in Singapore.

Methods

A de novo Markov model with three health states – stroke with long-term sequelae, no stroke, and death – was developed and simulated using Monte Carlo simulations with 10,000 iterations over a five-year time horizon from the Singapore healthcare system perspective. A 3% annual discount rate for costs and outcomes and monthly cycle lengths were used. By applying the longest available published clinical evidence, simulated patients received either TAVI or surgical aortic valve replacement (SAVR) and were at risk of adverse events (AEs) such as moderate-to-severe paravalvular aortic regurgitation (PAR).

Results

When five-year PARTNER 2A data was applied, base-case analyses showed that the incremental cost-effectiveness ratio (ICER) for TAVI compared to SAVR was US$315,760 per quality-adjusted life year (QALY) gained. The high ICER was due to high incremental implantation and procedure costs of TAVI compared to SAVR, and marginal improvement of 0.10 QALYs as simulated mortality of TAVI exceeded SAVR at 3.75 years post-implantation. One-way sensitivity analysis showed that the ICERs were most sensitive to cost of PAR, utility values of SAVR patients, and cost of TAVI and SAVR implants and procedures. When disutilities for AEs were additionally applied, the ICER decreased to US$300,070 per QALY gained. TAVI was dominated by SAVR when the time horizon increased to 20 years. Clinical outcomes projected from one-year PARTNER S3i data further reduced the ICER to US$86,337 per QALY gained for TAVI, assuming early all-cause mortality benefits from TAVI continued to persist. This assumption was undermined when longer term data showed that TAVI’s early mortality benefits diminished at five years.

Limitations and conclusion

TAVI is unlikely to be cost-effective in intermediate surgical-risk patients compared to SAVR in Singapore.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-022-08369-5.

MitraClip in Asia - Current Adoption and Regional Data

In the United States and Europe, percutaneous edge-to-edge repair of the mitral valve with the MitraClip device for patients with severe degenerative mitral regurgitation who are at prohibitive surgical risk has been well-established. Recent randomized controlled trials have also demonstrated significant clinical benefits with the use of the device in selected patients with functional mitral regurgitation. Thus far, >80,000 patients in more than 50 countries have undergone the MitraClip procedure. Despite the exponential growth worldwide, the rate of MitraClip adoption in Asia has been more gradual. In addition, very few publications describe the use of MitraClip in Asian populations. This review aims to describe the Asian experience with the MitraClip device and the challenges faced.

Economic burden of adverse drug reactions and potential for pharmacogenomic testing in Singaporean adults

Adverse drug reactions (ADRs) contribute to hospitalization but data on its economic burden is scant. Pre-emptive pharmacogenetic (PGx) testing can potentially reduce ADRs and its associated costs. The objectives of this study were to quantify the economic burden of ADRs and to estimate the breakeven cost of pre-emptive PGx testing in Singapore. We collected itemized costs for 1000 random non-elective hospitalizations of adults admitted to a tertiary-care general hospital in Singapore. The presence of ADRs at admission and their clinical characteristics were reported previously. The economic burden of ADRs was assessed from two perspectives: (1) Total cost and (2) incremental costs. The breakeven cost of PGx testing was estimated by dividing avoidable hospitalization costs for ADRs due to selected drugs by the number of patients taking those drugs. The total cost of 81 admissions caused by ADRs was US$570,404. Costs were significantly higher for bleeding/elevated international normalized ratio (US$9906 vs. US$2251, p = 6.58 × 10^-3) compared to other ADRs, and for drugs acting on the blood coagulation system (US$9884 vs. US$2229, p = 4.41 × 10^-3) compared to other drug classes. There were higher incremental laboratory costs due to ADRs causing or being present at admission. The estimated breakeven cost of a pre-emptive PGx test for patients taking warfarin, clopidogrel, chemotherapeutic and neuropsychiatric drugs was US$114 per patient. These results suggest that future studies designed to directly measure the clinical and cost impact of a pre-emptive genotyping program will help inform clinical practice and health policy decisions.

Transcatheter aortic valve implantation in Asia

The use of transcatheter aortic valve implantation (TAVI) to treat severe symptomatic aortic valve stenosis has increased exponentially in the last decade. This rapid expansion was seen predominantly in Western developed nations and has been fuelled by favorable results reported from a plethora of well-publicized randomized controlled trials, large retrospective series and national registries. Now, TAVI has become the standard of care for inoperable patients and an alternative to open surgery in patients who are at intermediate to high risk for open surgery. Notwithstanding these positive results, Asia has been relatively slow to adopt this technology despite a potentially large patient pool. Unique features of Asian medical environments and differences in Asian anatomy affecting TAVI uptake in Asia will be discussed. This article serves to outline the various challenging aspects of disseminating TAVI in Asian countries.

Mid-term study of transcatheter aortic valve implantation in an Asian population with severe aortic stenosis: two-year Valve Academic Research Consortium-2 outcomes

INTRODUCTION

Transcatheter aortic valve implantation (TAVI) is an effective treatment for high-risk or inoperative patients with severe aortic stenosis. Given the unique characteristics of Asian populations, questions regarding mid-term outcomes in Asians undergoing TAVI have yet to be addressed. We evaluated the two-year clinical outcomes of TAVI in an Asian population using Valve Academic Research Consortium-2 definitions.

METHODS

This prospective study recruited 59 patients from a major academic medical centre in Singapore. The main outcomes were two-year survival rates, peri-procedural complications, symptom improvement, valvular function and assessment of learning curve.

RESULTS

Mean age was 76.8 years (61.0% male), mean body surface area 1.6 m² and mean logistic EuroSCORE 18.7%. Survival was 93.2%, 86.0% and 79.1% at 30 days, one year and two years, respectively. At 30 days post TAVI, the rate of stroke was 1.7%, life-threatening bleeding 5.1%, acute kidney injury 25.0%, major vascular complication 5.1%, and new permanent pacemaker implantation 6.8%. 29.3% of TAVI patients were rehospitalised (47.1% cardiovascular-related) within one year. These composite outcomes were measured: device success (93.2%); early safety (79.7%); clinical efficacy (66.1%); and time-related valve safety (84.7%). Univariate analysis found these predictors of two-year all-cause mortality: logistic EuroSCORE (hazard ratio [HR] 1.07; p < 0.001); baseline estimated glomerular filtration rate (HR 0.97; p = 0.048); and acute kidney injury (HR 5.33; p = 0.022). Multivariate analysis identified non-transfemoral TAVI as a predictor of cardiovascular-related two-year mortality (HR 14.64; p = 0.008).

CONCLUSION

Despite the unique clinical differences in Asian populations, this registry demonstrated favourable mid-term clinical and safety outcomes in Asians undergoing TAVI.