Physical disabilities associated with MPS disorders have implications for children’s quality of life and psychosocial adjustment. However, few tools are available to quantify physical functioning and disability in this population. The caregiver-completed MPS Health Assessment Questionnaire (MPS-HAQ) (Skrinar and Cox, 2002) is a promising disease-specific instrument developed to measure disability in patients with MPS disorders (over age 8) and has been used to document enzyme treatment outcomes. However, the validity of the MPS-HAQ has not yet been established and normative data are not available. Our long-term goals are to 1) assess feasibility of using the MPS-HAQ with children under 8, 2) assess its sensitivity over time and 3) determine if modifications are necessary for younger children. In this abstract, we report on our preliminary efforts to examine how the MPS-HAQ distinguishes individuals with MPS from young, healthy, typically developing children and to describe associations between the MPS-HAQ and physical symptom severity.
Methods: As part of a larger normative study in typically-developing 4 to 7 year old children, we have administered the MPS-HAQ to 9 children to date. As part of a longitudinal study on MPS disorders, we have also administered it to individuals (aged 6 to 22 years) with MPS I to determine its association with the PSS (Physical Symptom Severity scale - measuring symptom severity in multiple organ systems).
Results: A significant (-0.87, p < .05) correlation was found between age and total score on the MPS-HAQ in typically-developing children. Among the MPS patients, a slight increase in disability with age was found. A longitudinal case report on two siblings with Hurler-Scheie over 10 years indicated increasing disability with age on the MPS-HAQ. A moderate association between the PSS score and the MPS-HAQ was found such that more medical problems were associated with a higher MPS-HAQ disability score.
Conclusions: We found that it was feasible to use the MPS-HAQ with typically developing 4 to 7 year-old children. Because of the strong associations with age, normative data will be necessary to correct for expected developmental level in MPS children. While the MPS-HAQ shows promise as a measure of disability, it requires validation to establish convergent and discriminant associations with relevant measures and new normative data collection with a larger sample to determine benchmarks for the age at which items are mastered independently and ages at which caregiver assistance is the norm. (Supported by the Lysosomal Disease Network, NIH U54NS065768, Genzyme-Sanofi)