Health State Utility Data in Cystic Fibrosis: A Systematic Review

Impact of sinus surgery in people with cystic fibrosis and chronic rhinosinusitis in the era of highly effective modulator therapy: Protocol for a prospective observational study

INTRODUCTION

Cystic fibrosis (CF) is commonly complicated by chronic rhinosinusitis (CRS). Despite highly effective management options, CRS in people with CF (PwCF+CRS) may be refractory to medical therapy, eventually requiring endoscopic sinus surgery. The impact of sinus surgery on pulmonary, quality of life (QOL), and other outcomes in PwCF+CRS in the expanding era of highly effective modulator therapy has not been fully elucidated. This study aims to determine if endoscopic sinus surgery can offer superior outcomes for PwCF+CRS when compared to continued medical treatment of CRS.

METHODS AND ANALYSIS

This multi-institutional, observational, prospective cohort study will enroll 150 adults with PwCF+CRS across nine US CF Centers who failed initial medical therapy for CRS and elected to pursue either endoscopic sinus surgery or continue medical treatment. To determine if sinus surgery outperforms continued medical therapy in different outcomes, we will assess changes in pulmonary, CF-specific QOL, CRS-specific QOL, sleep quality, depression, headache, cognition, olfaction, productivity loss, and health utility value after treatment. The influence of highly effective modulator therapy on these outcomes will also be evaluated. This study will provide crucial insights into the impact of endoscopic sinus surgery for PwCF+CRS and aid with development of future treatment pathways and guidelines.

ETHICS AND DISSEMINATION

This study has been approved by each institution's internal review board, and study enrollment began August 2019. Results will be disseminated in conferences and peer-reviewed journals.

TRIAL REGISTRATION

This study was registered on ClinicalTrials.gov (NCT04469439).

Cost-effectiveness analysis of genetic tools to predict treatment response in patients with cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) transmembrane conductance regulator (CFTR) modulator therapies show variable efficacy for patients with CF. Patient-derived predictive tools may identify individuals likely to respond to CFTRs, but are not in routine use. We aimed to determine the cost-utility of predictive tool-guided treatment with CFTRs as add-on to standard of care (SoC) for individuals with CF.

METHODS

This economic evaluation compared two strategies using an individual level simulation: (i) Treat All, where all patients received CFTRs plus SoC and (ii) Test→Treat, where patients who tested positive on predictive tools received CFTRs plus SoC and those who tested negative received SoC only. We simulated 50,000 individuals over their lifetime, and estimated costs (2020 CAD) per quality-adjusted life year (QALY) from the healthcare payer's perspective, discounted at 1.5% annually. The model was populated using Canadian CF registry data and published literature. Probabilistic and deterministic sensitivity were conducted.

RESULTS

The Treat All and Test→Treat and strategies yielded 22.41 and 21.36 QALYs, and cost $4.21 M and $3.15 M respectively. Results of probabilistic sensitivity analysis showed that Test→Treat was highly cost-effective compared to Treat All in 100% of simulations at cost-effectiveness thresholds as high as $500,000 per QALY. Test→Treat may save between $931 K to $1.1 M per QALY lost, depending on sensitivity and specificity of predictive tools.

CONCLUSION

The use of predictive tools could optimize the health benefits of CFTR modulators while reducing costs. Our findings support the use of pre-treatment predictive testing and may help inform coverage and reimbursement policies for individuals with CF.

Drug therapies for treatment of idiopathic pulmonary fibrosis: a systematic review, Bayesian network meta-analysis, and cost-effectiveness analysis

Background

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease with poor prognosis and a high economic burden for individuals and healthcare resources. Studies of the costs associated with the efficiency of IPF medications are scarce. We aimed to conduct a network meta-analysis (NMA) and cost-effectiveness analysis to identify the optimum pharmacological strategy among all currently available IPF regimens.

Methods

We first performed a systematic review and network meta-analysis. We searched eight databases for eligible randomised controlled trials (RCTs) published, in any language, between January 1, 1992 and July 31, 2022, that investigated the efficacy or tolerability (or both) of drug therapies for the treatment of IPF. The search was updated on February 1, 2023. Eligible RCTs were enrolled, with no restriction on dose, duration, or length of follow-up, if they included at least one of: all-cause mortality, acute exacerbation rate, disease progression rate, serious adverse events, and any adverse events under investigation. A subsequent Bayesian NMA within random-effects models was performed, followed by a cost-effectiveness analysis using the data obtained from our NMA, by developing a Markov model from the US payer's perspective. Assumptions were checked by deterministic and probabilistic sensitivity approaches to identify sensitive factors. We prospectively registered the protocol (CRD42022340590) in PROSPERO.

Findings

51 publications comprising 12,551 participants with IPF were analysed for the NMA, and the findings indicated that pirfenidone and N-acetylcysteine (NAC) + pirfenidone were the most efficacious and tolerable. The pharmacoeconomic analysis showed that NAC + pirfenidone was associated with the highest potentiality of being cost-effective at willingness-to-pay (WTP) thresholds of US$150,000 and $200,000, on the basis of quality-adjusted life years (QALYs), disability-adjusted life years (DALYs) and mortality, with the probability ranging from 53% to 92%. NAC was the minimum cost agent. Compared with placebo, NAC + pirfenidone improved effectiveness by increasing QALYs by 7.02, and reducing DALYs by 7.10 and deaths by 8.40, whilst raising overall costs by $516,894.

Interpretation

This NMA and cost-effectiveness analysis suggests that NAC + pirfenidone is the most cost-effective option for treatment of IPF at WTP thresholds of $150,000 and $200,000. However, given that clinical practice guidelines have not addressed the application of this therapy, large well-designed and multicentre trials are warranted to provide a better picture of IPF management.

Funding

None.

Characteristics of health-state utilities used in cost-effectiveness analyses: a systematic review of published studies in Asia

INTRODUCTION

Cost-utility analysis (CUA) is the preferred form of economic evaluation in many countries. As one of the key data inputs in cost-utility models, health state utility (HSU) has a crucial impact on CUA results. In the past decades, health technology assessment has been expanding rapidly in Asia, yet research examining the methodology and process used to generate cost-effectiveness evidence is scarce. The aim of this study was to examine the reporting of the characteristics of HSU data used in CUAs in Asia and how the characteristics have changed over time.

METHODS

A systematic literature search was performed to identify published CUA studies targeting Asian populations. Information was extracted for both the general characteristics of selected studies and the characteristics of reported HSU data. For each HSU value identified, we extracted data for four key characteristics, including 1) estimation method; 2) source of health-related quality of life (HRQoL) data; 3) source of preference data; and 4) sample size. The percentage of nonreporting was calculated and compared over two time periods (1990-2010 vs 2011-2020).

RESULTS

A total of 789 studies were included and 4,052 HSUs were identified. Of these HSUs, 3,351 (82.7%) were from published literature and 656 (16.2%) were from unpublished empirical data. Overall, the characteristics of HSU data were not reported in more than 80% of the studies. Of HSUs whose characteristics were reported, most of them were estimated using the EQ-5D (55.7%), Asian HRQoL data (91.9%), and Asian health preferences (87.7%); 45.7% of the HSUs was estimated with a sample of 100 or more individuals. All four characteristics showed improvements after 2010.

CONCLUSION

Over the past two decades, there has been a significant increase in CUA studies targeting Asian populations. However, HSU's characteristics were not reported in most of the CUA studies, making it difficult to evaluate the quality and appropriateness of the HSUs used in those cost-effectiveness studies.

Future therapies for cystic fibrosis

We are currently witnessing transformative change for people with cystic fibrosis with the introduction of small molecule, mutation-specific drugs capable of restoring function of the defective protein, cystic fibrosis transmembrane conductance regulator (CFTR). However, despite being a single gene disorder, there are multiple cystic fibrosis-causing genetic variants; mutation-specific drugs are not suitable for all genetic variants and also do not correct all the multisystem clinical manifestations of the disease. For many, there will remain a need for improved treatments. Those patients with gene variants responsive to CFTR modulators may have found these therapies to be transformational; research is now focusing on safely reducing the burden of symptom-directed treatment. However, modulators are not available in all parts of the globe, an issue which is further widening existing health inequalities. For patients who are not suitable for- or do not have access to- modulator drugs, alternative approaches are progressing through the trials pipeline. There will be challenges encountered in design and implementation of these trials, for which the established global CF infrastructure is a major advantage. Here, the Cystic Fibrosis National Research Strategy Group of the UK NIHR Respiratory Translational Research Collaboration looks to the future of cystic fibrosis therapies and consider priorities for future research and development.

A model-based economic analysis of the CFHealthHub intervention to support adherence to inhaled medications for people with cystic fibrosis in the UK

BACKGROUND

Adherence to preventative inhaled therapies in people with cystic fibrosis (CF) is low, resulting in potentially avoidable health losses and the need for costly rescue therapies.

OBJECTIVES

To estimate the cost-effectiveness of the CFHealthHub (CFHH) intervention to support adherence to inhaled medications.

METHODS

A state transition model was developed to assess the cost-effectiveness of the CFHH intervention versus usual care from the perspective of the UK National Health Service and Personal Social Services over a lifetime horizon. Costs and health outcomes were discounted at a rate of 3.5 percent per annum. Costs were valued at 2021/22 prices. The model structure includes health states defined by survival status, level of lung function, and transplant history. Treatment effects were modeled by changing the probabilities of transitioning between lung function states and reducing exacerbation rates. Model parameters were informed by the CFHH trial, CF Registry data, routine cost databases, literature, and expert opinion. Deterministic and probabilistic sensitivity analyses were undertaken to assess uncertainty.

RESULTS

The CFHH intervention is expected to generate additional health gains and cost savings compared with usual care. Assuming that it is delivered for 10 years, the CFHH intervention is expected to generate 0.17 additional quality-adjusted life years and cost savings of GBP 1,600 (EUR 1,662) per patient.

CONCLUSIONS

The CFHH intervention is expected to dominate usual care, irrespective of the duration over which the intervention is delivered. The modeled benefits and cost savings are smaller than initially expected and are sensitive to relative treatment effects on lung function.

Quality appraisal for systematic literature reviews of health state utility values: a descriptive analysis

BACKGROUND

Health state utility values (HSUVs) are an essential input parameter to cost-utility analysis (CUA). Systematic literature reviews (SLRs) provide summarized information for selecting utility values from an increasing number of primary studies eliciting HSUVs. Quality appraisal (QA) of such SLRs is an important process towards the credibility of HSUVs estimates; yet, authors often overlook this crucial process. A scientifically developed and widely accepted QA tool for this purpose is lacking and warranted.

OBJECTIVES

To comprehensively describe the nature of QA in published SRLs of studies eliciting HSUVs and generate a list of commonly used items.

METHODS

A comprehensive literature search was conducted in PubMed and Embase from 01.01.2015 to 15.05.2021. SLRs of empirical studies eliciting HSUVs that were published in English were included. We extracted descriptive data, which included QA tools checklists or good practice recommendations used or cited, items used, and the methods of incorporating QA results into study findings. Descriptive statistics (frequencies of use and occurrences of items, acceptance and counterfactual acceptance rates) were computed and a comprehensive list of QA items was generated.

RESULTS

A total of 73 SLRs were included, comprising 93 items and 35 QA tools and good recommendation practices. The prevalence of QA was 55% (40/73). Recommendations by NICE and ISPOR guidelines appeared in 42% (16/40) of the SLRs that appraised quality. The most commonly used QA items in SLRs were response rates (27/40), statistical analysis (22/40), sample size (21/40) and loss of follow up (21/40). Yet, the most commonly featured items in QA tools and GPRs were statistical analysis (23/35), confounding or baseline equivalency (20/35), and blinding (14/35). Only 5% of the SLRS used QA to inform the data analysis, with acceptance rates of 100% (in two studies) 67%, 53% and 33%. The mean counterfactual acceptance rate was 55% (median 53% and IQR 56%).

CONCLUSIONS

There is a considerably low prevalence of QA in the SLRs of HSUVs. Also, there is a wide variation in the QA dimensions and items included in both SLRs and extracted tools. This underscores the need for a scientifically developed QA tool for multi-variable primary studies of HSUVs.

'Mapping' Health State Utility Values from Non-preference-Based Measures: A Systematic Literature Review in Rare Diseases

BACKGROUND

The use of patient-reported outcome measures (PROMs) to monitor the effects of disease and treatment on patient symptomatology and daily life is increasing in rare diseases (RDs) (i.e. those affecting less than one in 2000 people); however, these instruments seldom yield health state utility values (HSUVs) for cost-utility analyses. In such a context, 'mapping' allows HSUVs to be obtained by establishing a statistical relationship between a 'source' (e.g. a disease-specific PROM) and a 'target' preference-based measure [e.g. the EuroQol-5 Dimension (EQ-5D) tool].

OBJECTIVE

This study aimed to systematically review all published studies using 'mapping' to derive HSUVs from non-preference-based measures in RDs, and identify any critical issues related to the main features of RDs, which are characterised by small, heterogeneous, and geographically dispersed patient populations.

METHODS

The following databases were searched during the first half of 2019 without time, study design, or language restrictions: MEDLINE (via PubMed), the School of Health and Related Research Health Utility Database (ScHARRHUD), and the Health Economics Research Centre (HERC) database of mapping studies (version 7.0). The keywords combined terms related to 'mapping' with Orphanet's list of RD indications (e.g. 'acromegaly') in addition to 'rare' and 'orphan'. 'Very rare' diseases (i.e. those with fewer than 1000 cases or families documented in the medical literature) were excluded from the searches. A predefined, pilot-tested extraction template (in Excel^®) was used to collect structured information from the studies.

RESULTS

Two groups of studies were identified in the review. The first group (n = 19) developed novel mapping algorithms in 13 different RDs. As a target measure, the majority used EQ-5D, and the others used the Short-Form Six-Dimension (SF-6D) and 15D; most studies adopted ordinary least squares (OLS) regression. The second group of studies (n = 9) applied previously published algorithms in non-RDs to comparable RDs, mainly in the field of cancer. The critical issues relating to 'mapping' in RDs included the availability of very few studies, the relatively high number of cancer studies, and the absence of research in paediatric RDs. Moreover, the reviewed studies recruited small samples, showed a limited overlap between RD-specific and generic PROMs, and highlighted the presence of cultural and linguistic factors influencing results in multi-country studies. Lastly, the application of existing algorithms developed in non-RDs tended to produce inaccuracies at the bottom of the EQ-5D scale, due to the greater severity of RDs.

CONCLUSIONS

More research is encouraged to develop algorithms for a broader spectrum of RDs (including those affecting young children), improve mapping study quality, test the generalisability of algorithms developed in non-RDs (e.g. HIV) to rare variants or evolutions of the same condition (e.g. AIDS wasting syndrome), and verify the robustness of results when mapped HSUVs are used in cost-utility models.