Estimation of the Quality-of-Life Impact of X-Linked Myotubular Myopathy

Assessment of health state utilities associated with adult and pediatric acid sphingomyelinase deficiency (ASMD)

INTRODUCTION

Acid sphingomyelinase deficiency (ASMD) type B is a rare genetic disorder leading to enlargement of the spleen and liver, pulmonary dysfunction, and other symptoms. Cost-utility analyses are often conducted to quantify the value of new treatments, and these analyses require health state utilities. Therefore, the purpose of this study was to estimate utilities associated with varying levels of severity of adult and pediatric ASMD type B.

METHODS

Seven adult and seven child health state vignettes describing ASMD were developed based on published literature, clinical trial results, and interviews with clinicians, patients with ASMD, and parents of children with ASMD. The health states were valued in time trade-off interviews with adult general population respondents in the UK.

RESULTS

Interviews were completed with 202 participants (50.0% female; mean age = 41.3 years). The health state representing ASMD without impairment had the highest mean utility for both the adult and child health states (0.92/0.94), and severe ASMD had the lowest mean utility (0.33/0.45). Every child health state had a significantly greater utility than the corresponding adult health state. Differences between adult/child paired states ranged from 0.02 to 0.13. Subgroup analyses explored the impact of parenting status on valuation of child health states.

DISCUSSION

Greater severity of ASMD was associated with lower mean utility. Results have implications for valuation of pediatric health states. The resulting utilities may be useful in cost-utility modeling estimating the value of treatment for ASMD.

Improving Interpretation of Evidence Relating to Quality of Life in Health Technology Assessments of Rare Disease Treatments

Rare diseases are often severe, debilitating, life-limiting conditions, many of which occur in childhood. These complex conditions have a wide range of clinical manifestations that have a substantial impact on the lives of patients, carers and families and often produce heterogeneous clinical outcomes. Therefore, the evaluation of quality-of-life (QoL) impacts is important. In health technology assessment (HTA), patient-reported outcome measures (PROMs) and/or health state utility values (HSUVs) are used to determine QoL impacts of new treatments, but their use in rare diseases is challenging due to small and heterogeneous populations and limited disease knowledge. This paper describes challenges associated with the use of patient-reported outcomes (PROs)/HSUVs to evaluate QoL in HTA of rare disease treatments (RDTs) and identifies five recommendations to ensure appropriate interpretation of QoL impacts. These were derived from mixed methods research (literature reviews, appraisal document analyses, appraisal committee observations and interviews) examining the use of PROs/HSUVs in HTA of RDTs. They highlight that HTAs of RDTs must (1) understand the QoL impacts of the disease and of treatments; (2) critically assess PRO data, recognising the nuances in development and administration of PROMs/HSUVs, considering what is feasible and what matters most to the patient population; (3) recognise that lack of significant effect on a PRO does not imply no QoL benefit; (4) use different forms of evidence to understand QoL impacts, such as patient input; and (5) provide methodological guidance to capture QoL impacts on patients/carers.

Estimating health state utilities in primary hyperoxaluria type 1: a valuation study

AIMS

Quantitative data on health state utilities in primary hyperoxaluria type 1 (PH1) are lacking. This study was conducted to estimate utility values in PH1 using 3 standard valuation techniques.

MATERIALS AND METHODS

Health state vignettes were developed with input from expert clinicians to describe different stages of chronic kidney disease (CKD) within the setting of PH1, along with a post-combined liver and kidney transplant (CLKT) health state ≥12 months following transplantation. The utility associated with living in each PH1 health state, as described by the vignettes, was evaluated by members of the UK general public using standard utility assessment techniques, including EQ-5D-5L, Visual Analog Scale, and Time Trade-Off.

RESULTS

A similar pattern across the three valuation methods was observed. Utility values were roughly constant from CKD stage 1-3b and then dropped sharply from these states to CKD stage 4. Decreases in utility in the later stages of CKD (stages 4-5) were followed by a recovery in quality of life in the post-CLKT health state.

LIMITATIONS

Vignettes may not fully capture the burden of living with PH1.

CONCLUSIONS

This study serves as an informative source of data on how the burden of PH1 varies across disease stages of CKD and post-CLKT in patients with PH1. The study findings highlight the unique clinical features of PH1 compared with non-PH1-related CKD, such as the need for earlier and more intensive hemodialysis, the risk of systemic oxalosis, and the potential need for CLKT (as opposed to kidney-only transplant). The impact of PH1 on health-related quality of life, which worsens once hemodialysis is required and systemic disease manifestations occur, is captured in this study using quantitative health state utilities. These data provide an understanding of the impact of PH1 on health-related quality of life and will facilitate health economic evaluation of future treatments.