OBJECTIVES : Obtaining utility values for disease modelling in rare conditions is challenging. Late-onset Pompe disease (LOPD), an inherited metabolic disorder, is characterised by progressive muscle weakness leading to increasing disability and patient dependence on wheelchair and ventilator use. There is scarce evidence on the utility associated with disability, however, SF-36 is frequently measured in clinical practice. This research aims to investigate the impact of need for wheelchair and ventilator use on utility in patients with LOPD using SF-36 data from the Pompe Registry (NTC00231400/Sanofi Genzyme).

METHODS : Six health states were defined based on the use (yes/no) of a wheelchair, non-invasive and invasive ventilation. Patient records including at least one complete SF-36 assessment were identified and SF-36 scores were mapped to EQ-5D index scores using a published algorithm derived from UK patient values (https://doi.org/10.1186/1477-7525-7-27). For each mapped utility value, the use of a wheelchair or ventilator was ascertained. Utility values were then summarised for each health state. No longitudinal analysis was undertaken.

RESULTS : The analysis included 708 patients: 94.2% have at some point received enzyme replacement therapy, 51.8% were female and the mean age at diagnosis was 40.2 years (standard deviation, SD, 16.6). A total of 4036 SF-36 measurements were mapped to EQ-5D index scores. Based on data for patients treated with enzyme replacement therapy, the mean utility was 0.69 (SD 0.19) for patients not using a wheelchair or ventilator. This was lower for other health states, with mean (SD) values ranging from 0.62 (0.18) in patients requiring non-invasive ventilation only, to 0.54 (0.25) in those using invasive ventilation, and to 0.50 (0.17) in wheelchair users.

CONCLUSIONS : The need for wheelchair and ventilator use in LOPD appears to negatively impact utility in these patients. The utility values derived from the Pompe Registry analysis will facilitate comprehensive modelling of disease progression.