Qualitative interviews to improve patient-reported outcome measures in late-onset Pompe disease: the patient perspective

Measuring health related quality of life (HRQoL) in Lysosomal Storage Disorders (LSDs): a rapid scoping review of available tools and domains

BACKGROUND

Lysosomal storage diseases (LSDs) are a group of rare inherited metabolic disorders, consisting of over 70 diseases that are characterised by lysosomal dysfunction. Due to their varied and progressive symptoms, LSDs have a continual impact on patients' health-related quality of life (HRQoL). Several recently published studies have provided insight into the HRQoL of individuals with LSDs. However, it is challenging to meaningfully synthesise this evidence, since studies often focus upon a particular type of LSD and / or utilise different self-report questionnaires or patient-reported outcome measures (PROMs) to assess HRQoL.

AIMS

The aim of this study was to review the published literature in LSDs, to identify the PROMs which have been used to assess HRQoL and generate a conceptual map of HRQoL domains measured in individuals diagnosed with LSDs.

METHODS

Three electronic databases were searched in March 2022. Primary studies of any design which utilised multi-item PROMs to assess at least one aspect of HRQoL in individuals with LSDs since 2017 were identified. Data were extracted to assess both the characteristics of each study and of the PROMs utilised within each study. The extraction of HRQoL domains and synthesis were informed by an a priori framework, inductively modified to reflect data emerging from the identified literature. Selection and extraction was undertaken independently by two reviewers; discrepancies were ratified by a third reviewer.

RESULTS

Sixty nine studies were identified which were published 2017-2022, with a combined total of 52 PROMs (71 variants) used to assess HRQoL in individuals with LSDs. The final extracted HRQoL framework included 7 domains (Activities; Physical sensations; Autonomy; Cognition; Feelings and emotions; Self-identity; Relationships), characterised by 37 sub-domains.

CONCLUSIONS

This review highlights the breadth and variety of HRQoL domains assessed in individuals with LSDs, across three broad domains of physical, psychological and social functioning. The resultant framework and mapped PROMs will aid researchers and clinicians in the selection of PROMs to assess aspects of HRQoL in people living with LSDs, based on their conceptual coverage.

Effect of avalglucosidase alfa on disease-specific and general patient-reported outcomes in treatment-naïve adults with late-onset Pompe disease compared with alglucosidase alfa: Meaningful change analyses from the Phase 3 COMET trial

BACKGROUND

The Phase 3 COMET trial (NCT02782741) comparing avalglucosidase alfa and alglucosidase alfa included health-related quality of life (HRQoL) assessments in treatment-naïve patients with late-onset Pompe disease (LOPD). Here, we further characterize results from disease-specific and general patient-reported outcome (PRO) measures.

METHODS

Adults who participated in the COMET trial receiving avalglucosidase alfa or alglucosidase alfa (both 20 mg/kg biweekly) during the 49-week double-blind treatment period were included in the analysis. Proportions of patients exceeding meaningful change thresholds at Week 49 were compared post hoc between treatment groups. PROs and their meaningful change thresholds included: Pompe Disease Severity Scale (PDSS; decrease 1.0-1.5 points), Pompe Disease Impact Scale (PDIS; decrease 1.0-1.5 points), Rasch-built Pompe-specific Activity Scale (R-PAct; change from unable to able to complete activity), 12-item Short Form Health Survey (SF-12; physical component summary [PCS] score: increase ≥6 points, mental component summary [MCS] score: increase ≥7 points), EuroQol 5 Dimension 5 Level (EQ-5D-5L; improvement of ≥1 category), and Patient Global Impression of Change (PGIC; any improvement).

RESULTS

The analysis included 99 adult patients (avalglucosidase alfa n = 50; alglucosidase alfa n = 49). Patients who received avalglucosidase alfa had significantly greater odds of achieving a meaningful change versus alglucosidase alfa for the PDSS Shortness of Breath (OR [95% CI] 11.79 [2.24; 62.18]), Fatigue/Pain (6.24 [1.20; 32.54]), Morning Headache (13.98 [1.71; 114.18]), and Overall Fatigue (5.88 [1.37; 25.11]) domains, and were significantly more likely to meet meaningful change thresholds across multiple PDSS domains (all nominal p < 0.05). A numerically greater proportion of patients in the avalglucosidase alfa group were able to complete selected activities of the R-PAct compared with the alglucosidase alfa group. Significantly greater proportions of patients who received avalglucosidase alfa achieved meaningful improvements for EQ-5D-5L usual activities dimension, EQ visual analog scale, and all four PGIC domains. The proportion of patients with improvements in SF-12 PCS and MCS was greater in the avalglucosidase alfa group versus alglucosidase alfa group, but was not significant (p > 0.05).

CONCLUSIONS

These analyses show that avalglucosidase alfa improves multiple symptoms and aspects of daily functioning, including breathing and mobility. This supports the clinical relevance of the effects of avalglucosidase alfa on HRQoL for patients with LOPD.

Measurement Properties of 2 Novel PROs, the Pompe Disease Symptom Scale and Pompe Disease Impact Scale, in the COMET Study

BACKGROUND AND OBJECTIVES

The Pompe Disease Symptom Scale (PDSS) and Impact Scale (PDIS) were created to measure the severity of symptoms and functional limitations experienced by patients with late-onset Pompe disease (LOPD). The objectives of this analysis were to establish a scoring algorithm and to examine the reliability, validity, and responsiveness of the measures using data from the COMET clinical trial.

METHODS

The COMET trial was a randomized, double-blind study comparing the efficacy and safety of avalglucosidase alfa and alglucosidase alfa in patients with LOPD aged 16-78 years at baseline. Adult participants (18 years or older) completed the PDSS and PDIS daily for 14 days at baseline and for 2 weeks before quarterly clinic visits for 1 year after randomization using an electronic diary. Data were pooled across treatment groups for the current analyses. Factor analysis and inter-item correlations were used to derive a scoring algorithm. Test-retest and internal consistency analyses examined the reliability of the measures. Correlations with criterion measures were used to evaluate validity and sensitivity to change. Anchor and distribution-based analyses were conducted to estimate thresholds for meaningful change.

RESULTS

Five multi-item domain scores were derived from the PDSS (Shortness of Breath, Overall Fatigue, Fatigue/Pain, Upper Extremity Weakness, Pain) and 2 from the PDIS (Mood, Difficulty Performing Activities). Internal consistency (Cronbach α > 0.90) and test-retest reliability (intraclass correlation >0.60) of the scores were supported. Cross-sectional and longitudinal correlations with the criterion measures generally supported the validity of the scores (r > 0.40). Within-patient meaningful change estimates ranging from 1.0 to 1.5 points were generated for the PDSS and PDIS domain scores.

DISCUSSION

The PDSS and PDIS are reliable and valid measures of LOPD symptoms and functional impacts. The measures can be used to evaluate burden of LOPD and effects of treatments in clinical trials, observational research, and clinical practice.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov identifier: NCT02782741.

Glycogen storage diseases

Glycogen storage diseases (GSDs) are a group of rare, monogenic disorders that share a defect in the synthesis or breakdown of glycogen. This Primer describes the multi-organ clinical features of hepatic GSDs and muscle GSDs, in addition to their epidemiology, biochemistry and mechanisms of disease, diagnosis, management, quality of life and future research directions. Some GSDs have available guidelines for diagnosis and management. Diagnostic considerations include phenotypic characterization, biomarkers, imaging, genetic testing, enzyme activity analysis and histology. Management includes surveillance for development of characteristic disease sequelae, avoidance of fasting in several hepatic GSDs, medically prescribed diets, appropriate exercise regimens and emergency letters. Specific therapeutic interventions are available for some diseases, such as enzyme replacement therapy to correct enzyme deficiency in Pompe disease and SGLT2 inhibitors for neutropenia and neutrophil dysfunction in GSD Ib. Progress in diagnosis, management and definitive therapies affects the natural course and hence morbidity and mortality. The natural history of GSDs is still being described. The quality of life of patients with these conditions varies, and standard sets of patient-centred outcomes have not yet been developed. The landscape of novel therapeutics and GSD clinical trials is vast, and emerging research is discussed herein.

A disease concept model for STXBP1-related disorders

OBJECTIVE

STXBP1-related disorders are rare genetic epilepsies and neurodevelopmental disorders, but the impact of symptoms across clinical domains is poorly understood. Disease concept models are formal frameworks to assess the lived experience of individuals and their families and provide a basis for generating outcome measures.

METHODS

We conducted semistructured, qualitative interviews with 19 caregivers of 16 individuals with STXBP1-related disorders and 7 healthcare professionals. We systematically coded themes using NVivo software and grouped concepts into the domains of symptoms, symptom impact, and caregiver impact. We quantified the frequency of concepts throughout the lifespan and across clinical subgroups stratified by seizure history and developmental trajectories.

RESULTS

Over 25 hours of interviews, we coded a total of 3626 references to 38 distinct concepts. In addition to well-recognized clinical features such as developmental delay (n = 240 references), behavior (n = 201), and seizures (n = 147), we identified previously underrepresented symptoms including gastrointestinal (n = 68) and respiratory symptoms (n = 24) and pain (n = 30). The most frequently referenced symptom impacts were autonomy (n = 96), socialization (n = 64), and schooling (n = 61). Emotional impact (n = 354), support (n = 200), and daily life & activities (n = 108) were highly cited caregiver impacts. We found that seizures were more commonly referenced in infancy than in other age groups, while behavior and socialization were more likely to be referred to in childhood. We found that caregivers of individuals with ongoing seizures were less likely to reference developmental delay, possibly due to the relatively high impact of seizures.

SIGNIFICANCE

STXBP1-related disorders are complex conditions affecting a wide range of clinical and social domains. We comprehensively mapped symptoms and their impact on families to generate a comprehensive disease model as a foundation for clinical endpoints in future trials.