A post hoc analysis of Projected Retained Ability Scores (PRAS) for the longitudinal assessment of cognitive functioning in patients with neuronopathic mucopolysaccharidosis II receiving intrathecal idursulfase-IT

Table 1 Cognitive categories defined by baseline DAS-II GCA score, endpoint GCA score, and PRAS

Cognitive category	Description	Definition^a
Above-average cognitive growth rate	Absolute and relative improvement, at a faster rate than same-age developmental norms	Endpoint GCA score − baseline GCA score > 10
Average cognitive growth rate	Absolute improvement, with relative improvement at the same rate as same-age developmental norms (stable GCA relative to norms)	Endpoint GCA score − baseline GCA score between −10 and 10
Below-average cognitive growth rate	Absolute improvement at a slower rate than same-age developmental norms, reflecting a relative decline (compared with normative development)	Endpoint GCA score − baseline GCA < −10 AND endpoint GCA score—PRAS > 10
Plateauing cognitive functioning	No absolute change, reflecting a relative decline (compared with normative development)	Endpoint GCA score − baseline GCA score < −10 AND endpoint GCA score—PRAS between −10 and 10
Deteriorating cognitive functioning	Absolute and relative decline	Endpoint GCA score − baseline GCA score) < −10 AND endpoint GCA score—PRAS < −10

^aSeven patients younger than 3.5 years old at baseline transitioned from the DAS-II Early Years battery levels from the Early Years Lower Level (2.5–< 3.5 years; four subtests) to the Early Years Upper Level (3.5–< 7 years; six subtests) during the study; for these patients, developmental changes were evaluated based on a prorated GCA score at follow-up visits based on the four subtests in the Early Years Lower Level
DAS-II Differential Ability Scales, Second Edition; GCA General Conceptual Ability; PRAS Projected Retained Ability Score

ISSN: 1750-1172