Table 1.

Grading of severity of impairment across multiple domains

	Mild	Moderate	Severe
Cognition	Cognitive Z score <−1 for more than one test, or mean Z score <−1 for a construction task and non-verbal task, or mean Z score <−1 for verbal tasks	Cognitive Z score <−2 for more than one test, or mean Z score <−2 for a construction task and non-verbal task, or mean Z score <−2 for verbal tasks	Z score <−3 for more than one severe test, or mean Z score <−3, or mean Z score <−3 for verbal tasks
Motor	Difficulty in everyday motor activities appropriate for age but able to move around without help	Difficulty in holding implements, dressing, and sitting upright. Able to move around with help	Inability to walk and absence of functional use of hands
Hearing	Audiometric hearing threshold level of 26–30 dB HL in children aged <15 years and 26–40 dB HL in adults	Audiometric hearing threshold level of 31–60 dB HL in children aged <15 years and 41–60 dB HL in adults. Hearing aid not normally used. Or, audiometric hearing threshold level of 31–60 dB HL in children aged <15 years and 41–60 dB HL in adults. Hearing aid normally used	Audiometric hearing threshold level of 61 dB HL or greater. Hearing aid not normally used. Or, audiometric hearing threshold level of 61 dB HL or greater. Hearing aid normally used
Vision	Visual acuity in the best eye of <6/12 but ≥6/18, or corresponding visual field loss	Visual acuity in the best eye of <6/18 but ≥6/60; or, corresponding visual field loss	Visual acuity in the best eye of <6/60 but >3/60; or, visual field loss with blindness (visual acuity in the best eye of <3/60); or, corresponding visual field loss
Seizure disorder	More than one non-febrile seizure per year	More than one non-febrile seizure per month	More than one non-febrile seizure per week
Behavioural*	Any reported	..	..
Multidomain	One or two domains mildly affected	Three or more domains mildly affected, or one moderately affected and more than one mildly affected	If any domain is severely affected, or two or more are moderately affected

HL=hearing level.

^*Definitions of behavioural problems could not be standardised or assessed.