TABLE 9-1, Classifications of Intellectual Disability Severity - Mental Disorders and Disabilities Among Low-Income Children

Severity Category	Approximate Percent Distribution of Cases by Severity	DSM-IV Criteria (severity levels were based only on IQ categories)	DSM-5 Criteria (severity classified on the basis of daily skills)	AAIDD Criteria (severity classified on the basis of intensity of support needed)	SSI Listings Criteria (The SSI listings do not specify severity levels, but indicate different standards for meeting or equaling listing level severity.)
Mild	85%	Approximate IQ range 50–69	Can live independently with minimum levels of support.	Intermittent support needed during transitions or periods of uncertainty.	IQ of 60 through 70 and a physical or other mental impairment imposing an additional and significant limitation of function
Moderate	10%	Approximate IQ range 36–49	Independent living may be achieved with moderate levels of support, such as those available in group homes.	Limited support needed in daily situations.	A valid verbal, performance, or full-scale IQ of 59 or less
Severe	3.5%	Approximate IQ range 20–35	Requires daily assistance with self-care activities and safety supervision.	Extensive support needed for daily activities.	A valid verbal, performance, or full-scale IQ of 59 or less
Profound	1.5%	IQ <20	Requires 24-hour care.	Pervasive support needed for every aspect of daily routines.	A valid verbal, performance, or full-scale IQ of 59 or less

Severity Category

Approximate Percent Distribution of Cases by Severity

DSM-IV Criteria (severity levels were based only on IQ categories)

DSM-5 Criteria (severity classified on the basis of daily skills)

AAIDD Criteria (severity classified on the basis of intensity of support needed)

SSI Listings Criteria (The SSI listings do not specify severity levels, but indicate different standards for meeting or equaling listing level severity.)

Mild

85%

Approximate IQ range 50–69

Can live independently with minimum levels of support.

Intermittent support needed during transitions or periods of uncertainty.

IQ of 60 through 70 and a physical or other mental impairment imposing an additional and significant limitation of function

Moderate

10%

Approximate IQ range 36–49

Independent living may be achieved with moderate levels of support, such as those available in group homes.

Limited support needed in daily situations.

A valid verbal, performance, or full-scale IQ of 59 or less

Severe

3.5%

Approximate IQ range 20–35

Requires daily assistance with self-care activities and safety supervision.

Extensive support needed for daily activities.

A valid verbal, performance, or full-scale IQ of 59 or less

Profound

1.5%

IQ <20

Requires 24-hour care.

Pervasive support needed for every aspect of daily routines.

A valid verbal, performance, or full-scale IQ of 59 or less

From: 9, Clinical Characteristics of Intellectual Disabilities

Mental Disorders and Disabilities Among Low-Income Children.

Committee to Evaluate the Supplemental Security Income Disability Program for Children with Mental Disorders; Board on the Health of Select Populations; Board on Children, Youth, and Families; Institute of Medicine; Division of Behavioral and Social Sciences and Education; The National Academies of Sciences, Engineering, and Medicine; Boat TF, Wu JT, editors.

Washington (DC): National Academies Press (US); 2015 Oct 28.

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.

TABLE 9-1Classifications of Intellectual Disability Severity