Evolution of mobility, pain/discomfort, self-care, and mental health in patients with alpha-mannosidosis: an international caregiver and patient survey

Abstract

BACKGROUND: Alpha-mannosidosis is a rare recessive lysosomal storage disorder with progressive multi-systemic impacts. In the absence of standardized monitoring protocols, there is insufficient understanding of disease progression over time. This study explored the evolution of the burden of illness and quality of life (QoL) experienced by patients with alpha-mannosidosis via an international patient and caregiver-based survey. The online survey was distributed to adult patients/caregivers of patients ? 10 years old. It included visual analogue scales (VAS; timepoints 5 years ago and now), multiple choice, and open text questions. We report a subset of functional and QoL data: walking ability, pain/discomfort, ability to self-care, and mental health. RESULTS: Analyses include 51 responses from 18 countries: 26 patients were on velmanase alfa enzyme replacement therapy (ERT), seven had been treated with hematopoietic stem cell transplantation (HSCT) and 18 were untreated patients (UP). Over 5 years, VAS scores showed the least decline in walking ability for HSCT patients (+ 0.1 ± 1.9) compared to patients receiving ERT (+ 0.7 ± 1.2) and UP (+ 1.8 ± 2.0). A trend towards improvement in pain was only observed for those on ERT (-0.2 ± 2.0), both for pediatric and adult patients. Ability to self-care improved for patients treated with HSCT (-1.0 ± 1.8) and slightly improved with ERT (-0.3 ± 1.5) but worsened for UP (+ 0.6 ± 0.9). Similarly, a trend towards improvement in mental health scores was observed for patients on ERT (-0.4 ± 2.2). CONCLUSIONS: Alpha-mannosidosis is associated with a substantial and progressive burden in UP, including deterioration in walking ability, pain, self-care and mental health. The survey results suggest that treatment with ERT or HSCT may slow this natural progression of alpha-mannosidosis, with these patients following a different disease trajectory to those solely receiving supportive care. This study could inform the natural pathway of alpha-mannosidosis to recognize patients' needs, courses of care, and the design of interventional studies.