OBJECTIVES: Approximately two-thirds of patients with the rare lysosomal storage disease mucopolysaccharidosis II (MPS II; Hunter syndrome) are affected by cognitive impairment (CI). We aimed to characterize clinical features and healthcare resource utilization in patients with MPS II with or without CI.

METHODS: Patients diagnosed with MPS II between 1997 and 2017 were assessed in a retrospective medical chart review at 19 US sites. CI status was determined based on whether cognitive delay was ever documented in the patient’s chart. Clinical characteristics and resource utilization were summarized for patients with or without CI.

RESULTS: Overall, 140 male patients (18 deceased) were included. CI was reported in 87 patients (62.1%) at any time during the study; 79.3% of patients with CI and 75.0% of those without CI had received enzyme replacement therapy. Among patients with CI, 55.2% had first documentation of CI before age 6 years and 37.9% had first documentation between ages 6 and 11. Somatic symptom burden was high for patients with and without CI; however, those with CI were generally younger at first documentation of symptoms. Developmental delays occurred more frequently in patients with CI than in those without: communication, 94.3% versus 30.2%; toileting, 71.3% versus 15.1%; motor, 58.6% versus 24.5%. Resource utilization (at least one instance between birth and last visit; n=75 patients with CI and n=48 without) was higher in patients with CI than in those without: hospitalization, 58.7% versus 39.6%; emergency room visits, 74.7% versus 33.3%, supportive services, 84.0% versus 58.3%.

CONCLUSIONS: Patients with MPS II and CI experience a high symptom burden, with earlier documentation of symptoms and more frequent developmental delays than patients without CI. Higher healthcare resource utilization was reported for patients with CI than those without CI. Shire (a Takeda company) funded this study and writing support.