Systematic review and cost-effectiveness of bosentan and sildenafil as therapeutic drugs for pediatric pulmonary arterial hypertension

Issues, Challenges and Opportunities for Economic Evaluations of Orphan Drugs in Rare Diseases: An Umbrella Review

BACKGROUND AND OBJECTIVES

There are significant challenges when obtaining clinical and economic evidence for health technology assessments of rare diseases. Many of them have been highlighted in previous systematic reviews but they have not been summarised in a comprehensive manner. For all stakeholders working with rare diseases, it is important to be aware and understand these issues. The objective of this review is to identify the main challenges for the economic evaluation of orphan drugs in rare diseases.

METHODS

An umbrella review of systematic reviews of economic studies concerned with orphan and ultra-orphan drugs was conducted. Studies that were not systematic reviews, or on advanced therapeutic medicinal products, personalised medicines or other interventions that were not considered orphan drugs were excluded. The database searches included publications from 2010 to 2023, and were conducted in MEDLINE, EMBASE and the Cochrane library using filters for systematic reviews, and economic evaluations and models. These filters were combined with search terms for rare diseases and orphan drugs. A hand search supplemented the literature searches. The findings were reported by a compliant Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram.

RESULTS

Two hundred and eighty-two records were identified from the literature searches, of which 64 were duplicates, whereas five reviews were identified from the hand search. A total of 36 reviews were included after screening against inclusion/exclusion criteria, 35 from literature searches and one from hand searching. Of those studies 1, 27 and 8 were low, moderate and high quality, respectively. The reviews highlight the scarcity of evidence for health economic parameters, for example, clinical effectiveness, costs, quality of life and the natural history of disease. Health economic evaluations such as cost-effectiveness and budget-impact analyses were scarce, and generally low-to-moderate quality. The causes were limited health economic parameters, together with publications bias, especially for cost-effectiveness analyses.

CONCLUSIONS

The results highlighted issues around a considerable paucity of evidence for economic evaluations and few cost-effectiveness analyses, supporting the notion that a paucity of evidence makes economic evaluations of rare diseases more challenging compared with more prevalent diseases. Furthermore, we provide recommendations for more sustainable approaches in economic evaluations of rare diseases.

Cost-utility of ambrisentan and bosentan for pediatric pulmonary arterial hypertension

INTRODUCTION

Despite the increasing evidence supporting the efficacy of ambrisentan and bosentan in improving functional classes among pediatric patients with pulmonary arterial hypertension (PAH), there is a lack of information regarding their cost implications. Therefore, the objective of this study is to assess the cost-utility of bosentan compared to ambrisentan for the treatment of pediatric patients with PAH in Colombia.

METHODS

We employed a Markov model to estimate the costs and quality-adjusted life-years (QALYs) associated with the use of ambrisentan or bosentan in pediatric patients diagnosed with pulmonary arterial hypertension (PAH). To ensure the reliability of our findings, we conducted sensitivity analyses to assess the robustness of the model. In our cost-effectiveness analysis, we evaluated the outcomes at a willingness-to-pay (WTP) threshold of US$5,180.

RESULTS

The expected annual cost per patient receiving ambrisentan was estimated to be $16,055 (95% CI 15,937 -16,172), while for bosentan it was $14,503 (95% CI 14,489 -14,615). The QALYs per person estimated for ambrisentan were 0.39 (95% CI 0.381-0.382), whereas for bosentan it was 0.40 (95% CI 0.401-0.403).

CONCLUSION

Our economic evaluation shows that ambrisentan is not cost-effective regarding bosentan to in treating pulmonary arterial hypertension in C.

Phosphodiesterase 5 Inhibitor for Pediatric Pulmonary Arterial Hypertension: A Cost-Utility Analysis

OBJECTIVES

Despite the growing evidence of efficacy, scarce information exists regarding the cost of tadalafil to improve the functional classes of pediatric patients with pulmonary arterial hypertension. This study aims to determine the cost-utility of tadalafil compared sildenafil to treat pediatric patients with pulmonary arterial hypertension in Colombia.

METHODS

A Markov model was developed to compare expected costs, outcomes, and quality-adjusted life-years of sildenafil and tadalafil in pediatric patients with pulmonary arterial hypertension. The model was analyzed probabilistically, and a value of information analysis was conducted to inform the value of conducting further research to reduce current uncertainties in the evidence base. Cost-effectiveness was evaluated at a willingness-to-pay value of US $5180.

RESULTS

The mean incremental cost of tadalafil versus sildenafil is US $15 270. The 95% credible interval for the incremental cost ranges from US $28 033.65 to US $5940.86. The mean incremental benefit of tadalafil versus sildenafil is 1.00 quality-adjusted life-years (QALY). The 95% credible interval for the incremental benefit ranges from 1.88 to 0.31 QALY. The expected incremental cost per QALY is estimated at US $15 286. There is a probability less than 1% that tadalafil is more cost-effective than sildenafil at a threshold of US $5180 per QALY. Form the value of information analysis, the theoretical upper bound on the value of further research was US $9.298 for Colombia.

CONCLUSION

Our economic evaluation shows that tadalafil is not cost-effective regarding sildenafil to treat pediatric patients with pulmonary arterial hypertension in Colombia. Our study provides evidence that should be used by decision-makers to improve clinical practice guidelines.

Cost-Effectiveness Analysis of Macitentan in Comparison With Bosentan in the Treatment of Pulmonary Arterial Hypertension in Iran

OBJECTIVES

Pulmonary arterial hypertension (PAH) is a chronic and progressive disease that, if left untreated, shortens the life expectancy of patients. Endothelin receptor antagonists, such as macitentan and bosentan, play an essential role in improving the patient's symptoms, quality of life, and life expectancy. This study aimed to evaluate the cost-utility of macitentan compared with bosentan in treating PAH from the health system perspective in Iran.

METHODS

For evaluating the cost-effectiveness of macitentan, a Markov model consisting of 5 states, functional class (FC) I, FC II, FC III, FC IV, and death, was designed using the TreeAge software. The lifetime time horizon and a 3-month cycle length were set. Patients entered the model from FC II or FC III states based on the initial probabilities. Costs were measured in US dollars (USD), and outcomes were measured in terms of quality quality-adjusted life-years (QALYs). Consequently, the incremental cost-effectiveness ratio (ICER) was calculated. In addition, sensitivity analysis was performed to determine the robustness of the model by examining the possible effects of uncertainties on the final result.

RESULTS

The costs of treatment with macitentan and bosentan in PAH in Iran were calculated at 19 429 and 17 246 USD, and the outcomes were 4.02 and 3.04 QALYs, respectively. Therefore, ICER was calculated at 2233.46 USD/QALY. One-way sensitivity analysis demonstrates that the model is robust; nevertheless, it is most sensitive to the price of macitentan and bosentan.

CONCLUSION

Treatment with macitentan was associated with both higher costs and QALYs than bosentan. Nevertheless, it is considered the cost-effective treatment strategy in Iran given that the calculated ICER falls below the willingness to pay threshold.

Ambrisentan for in pediatric pulmonary arterial hypertension: A cost-utility analysis

INTRODUCTION

Despite the growing evidence of efficacy, little is known regarding the efficiency of ambrisentan to decrease cost and improve the functional classes of pediatric patients with pulmonary arterial hypertension. This study aims to determine the cost-utility of ambrisentan regarding sildenafil to treat pediatric patients with pulmonary arterial hypertension in Colombia.

METHODS

A decision tree model was used to estimate the cost and quality-adjusted life-years (QALYs) of ambrisentan, or sildenafil in pediatric patients with pulmonary arterial hypertension. Multiple sensitivity analyses were conducted to evaluate the robustness of the model. Cost-effectiveness was evaluated at a willingness-to-pay (WTP) value of US$5180.

RESULTS

The base-case analysis showed that compared with sildenafil, ambrisentan was associated with higher costs and higher QALYs. The expected annual cost per patient with ambrisentan was US$16,105 and with sildenafil was US$1431. The QALYs per person estimated with ambrisentan was 0.40 and for sildenafil was 0.39. The estimated improvement in quality of life and reduced costs results in an estimate of economic dominance for sildenafil over ambrisentan.

CONCLUSION

Our economic evaluation shows that ambrisentan is not cost-effective regarding sildenafil to treat pediatric patients with pulmonary arterial hypertension in Colombia. Our study provides evidence that should be used by decision-makers to improve clinical practice guidelines.

Long-Term Study on Therapeutic Strategy for Treatment of Eisenmenger Syndrome Patients: A Case Series Study

Eisenmenger syndrome (ES) refers to congenital heart diseases (CHD) with reversal flow associated with increased pulmonary pressure and irreversible pulmonary vascular remodeling. Previous reports showed limited therapeutic strategies in ES. In this study, 5 ES patients (2 males and 3 females), who had been followed regularly at our institution from 2010 to 2019, were retrospectively reviewed. We adopted an add-on combination of sildenafil, bosentan, and iloprost and collected the clinical characteristics and outcomes as well as findings of echocardiography, computed tomography, pulmonary perfusion-ventilation scans, positron emission tomography, and biomarkers. The age of diagnosis in these ES patients ranged from 23 to 54 years (38.2 ± 11.1 years; mean ± standard deviation), and they were followed for 7 to 17 years. Their mean pulmonary arterial pressure and pulmonary vascular resistance index were 56.4 ± 11.3 mmHg and 24.7 ± 8.5 WU.m², respectively. Intrapulmonary arterial thrombosis was found in 4 patients, ischemic stroke was noted in 2 patients, and increased glucose uptake of the right ventricle was observed in 4 patients. No patient mortality was seen within 5 years of follow-up. Subsequently, 2 patients died of right ventricular failure, 1 died of sepsis related to brain abscess, and another died of sudden death. The life span of these patients was 44–62 years. Although these patients showed longer survival, the beneficial data on specific-target pharmacologic interventions in ES is still preliminary. Thus, larger trials are warranted, and the study of cardiac remodeling in ES from various CHD should be explored.