Systematic Literature Review to Assess Economic Evaluations in Spinal Muscular Atrophy (SMA)

Healthcare resource utilisation and direct medical cost for individuals with 5q spinal muscular atrophy in Sweden

BACKGROUND

Spinal muscular atrophy (SMA) is a rare, progressive, neuromuscular disorder. Recent advances in treatment require an updated assessment of burden to inform reimbursement decisions.

OBJECTIVES

To quantify healthcare resource utilisation (HCRU) and cost of care for patients with SMA.

METHODS

Cohort study of patients with SMA identified in the Swedish National Patient Registry (2007-2018), matched to a reference cohort grouped into four SMA types (1, 2, 3, unspecified adult onset [UAO]). HCRU included inpatient admissions, outpatient visits, procedures, and dispensed medications. Direct medical costs were estimated by multiplying HCRU by respective unit costs. Average annual HCRU and medical costs were modelled for SMA versus reference cohorts to estimate differences attributable to the disease (i.e., average treatment effect estimand). The trajectory of direct costs over time were assessed using synthetic cohorts.

RESULTS

We identified 290 SMA patients. Annualised HCRU was higher in SMA patients compared with reference cohorts. Highest risk ratios were observed for inpatient overnight stays for type 1 (risk ratio [RR]: 29.2; 95% confidence interval [CI]: 16.0, 53.5) and type 2 (RR: 23.3; 95% CI: 16.4,33.1). Mean annual direct medical costs per patient for each year since first diagnosis were greatest for type 1 (€114,185 and SMA-attributable: €113,380), type 2 (€61,876 and SMA-attributable: €61,237), type 3 (€45,518 and SMA-attributable: €44,556), and UAO (€4046 and SMA-attributable: €2098). Costs were greatest in the 2-3 years after the first diagnosis for all types.

DISCUSSION AND CONCLUSION

The economic burden attributable to SMA is significant. Further research is needed to understand the burden in other European countries and the impact of new treatments.

Review of economic modeling evidence from NICE appraisals of rare disease treatments for spinal muscular atrophy

INTRODUCTION

The National Institute of Health and Care Excellence (NICE) in England has appraised three treatments for spinal muscular atrophy (SMA), namely, nusinersen, onasemnogene abeparvovec, and risdiplam. As rare disease treatments (RDTs) commonly face challenges in health technology assessment (HTA) processes due to their clinical and economic uncertainties, an in-depth review of these appraisals is useful to enable a deeper understanding of economic modelling considerations for SMA.

AREAS COVERED

This review is a detailed analysis of NICE appraisals for SMA and aims to compare the economic modelling evidence of the three RDTs. This is done by examining differences and similarities and by discussing critical outstanding issues across the economic evaluations of the appraisals.

EXPERT OPINION

This article aims to contribute to the development of evidence that can be used as guidance to inform resource allocation decisions for RDTs for SMA, but also to be a resource about approaches for the generation, analysis and interpretation of economic modelling evidence for RDTs more broadly.

Newborn Screening for SMA – Can a Wait-and-See Strategy be Responsibly Justified in Patients With Four SMN2 Copies?

Background: Early treatment after genetic newborn screening for SMA significantly improves outcomes in infantile SMA. However, there is no consensus in the SMA treatment community about early treatment initiation in patients with four copies of SMN2. Objective: Approach to a responsible treatment strategy for SMA patients with four SMN2 copies detected in newborn screening. Methods: Inclusion criteria were a history of SMA diagnosed by NBS, age >  12 months at last examination, and diagnosis of four SMN2 copies at confirmatory diagnosis. Results: 21 patients with SMA and four SMN2 copies were identified in German screening projects over a three-year period. In three of them, the SMN2 copy number had to be corrected later, and three patients were lost to follow-up. Eight of the fifteen patients who were subject to long-term follow-up underwent presymptomatic therapy between 3 and 36 months of age and had no definite disease symptoms to date. Five of the other seven patients who underwent a strict follow-up strategy, showed clinical or electrophysiological disease onset between 1.5 and 4 years of age. In two of them, complete recovery was not achieved despite immediate initiation of treatment after the onset of the first symptoms. Conclusion: A remarkable proportion of patients with four copies of SMN2 develop irreversible symptoms within the first four years of life, if a wait-and-see strategy is followed. These data argue for a proactive approach, i.e., early initiation of treatment in this subgroup of SMA patients.

Systematic Literature Review to Identify Utility Values in Patients with Spinal Muscular Atrophy (SMA) and Their Caregivers

BACKGROUND

Spinal muscular atrophy (SMA) is a progressive neuromuscular disorder that has a substantial impact on health-related quality of life for patients with SMA and their caregivers. Utility values ('utilities') are used in health economic analyses to incorporate individual or societal perspectives regarding the desirability of health outcomes such as a certain health state or change in health states over time.

OBJECTIVES

The primary objective of this systematic literature review (SLR) was to identify published utilities associated with patients with SMA and their caregivers and to determine the extent to which Health Technology Assessment (HTA) requirements of methods used to generate utilities are met. A secondary objective was to broaden the scope to identify utilities associated with other (non-SMA) neuromuscular disorders.

METHODS

A comprehensive search to capture published utilities associated with patients with SMA and their caregivers was performed in 2019 and updated in 2021 using several electronic databases in addition to supplementary sources. As we anticipated that few published utilities associated with SMA would be identified, the search also captured utilities for other (non-SMA) neuromuscular disorders that may serve as useful surrogate values for studies of SMA and other rare diseases. Electronic searches were performed in Embase, MEDLINE, Evidence-Based Medicine Reviews, and EconLit via the Ovid platform and were supplemented by searches of the grey literature (reference lists, conference proceedings, global HTA body websites, and other relevant sources). Study eligibility criteria were based on the population, interventions, comparators, and outcomes (PICO) framework. The quality of the full-text publications was assessed using a checklist based on UK National Institute for Health and Care Excellence technical support documents.

RESULTS

In total, 14 publications that reported SMA-related patient or caregiver utilities or disutilities met the eligibility criteria to be included in the SLR; the included studies demonstrate the substantial health-related quality-of-life burden of SMA on both patients with SMA and their caregivers. A variety of preference-based measures were used to derive utilities for patients with SMA and their caregivers. Different methods for collecting utility data included patient and proxy assessment of health states using questionnaires, vignette methodologies, structured forms of expert elicitation, and mapped data from results of clinical trials. A range of utilities was reported from both patient- and proxy-reported data, which reflects the degree of disability associated with early- and later-onset SMA. Methods for deriving utilities were assessed with respect to three reference cases from HTA bodies in the UK, the USA, and Canada. None of the 14 publications met the requirements of all three HTA bodies because of differing tariff requirements between countries; one study met the requirements of HTA bodies in Canada and the UK. Also, six studies did not report the method of valuation, which precluded analysis with respect to the HTA reference cases.

CONCLUSIONS

This SLR provides a comprehensive repository of the currently available utilities relevant to patients with SMA and their caregivers. This SLR provides recommendations for establishing consensus on the approach to generating utility values for the SMA patient population and their caregivers for health economic decisions.