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

Abstract

Background Spinal muscular atrophy (SMA) is a progressive neuromuscular disorder that has a substantial impact on healthrelated 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 ...

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“…Such difference in the strength of patient and carer preferences echoes differences in the utilities of patients and carers described by Paracha et al [11]. Many carers described the health states of those they cared for as 'worse than dead', while most patients described these states as having positive utility.…”

“…Paracha et al [11] make a similar observation around the difficulty of interpreting health state utilities. Their systematic review of health state utilities finds a wide mix of methodologies and perspectives.…”

“…The review of economic evaluations also raises the importance of measuring outcomes that are important to patients. As observed by Paracha et al [11] , small changes in fine motor functioning that may not be captured by instruments such as the EQ-5D can be very valuable to patients. This emphasises the importance of understanding patient preferences for treatment and outcomes.…”

Utility estimations of different health states of patients with type I, II, and III spinal muscular atrophy in China: A mixed approach study with patient and proxy-reported data

“…Thirdly, we adopted a mixed patient/proxy-derived utilities for patients with SMA, which may result in unintentional bias from proxy assessments. For example, parents and caregivers usually have knowledge of one child with SMA, which may skew their interpretation of a particular health state ( 45 ). Fourthly, the using of Chinese value set for EQ-5D-3L in EQ-5D-Y-3L is a consequent limitation due to the lack of Chinese specific value set for EQ-5D-Y-3L.…”

Systematic Literature Review of the Natural History of Spinal Muscular Atrophy

“…However, these data remain critical to understand and effectively demonstrate long-term treatment outcomes and to evaluate the physical, social, and economic burden of the disease for patients and caregivers. 11,12…”