GMFM (GMFM-66 & GMFM-88) User's Manual, 2nd edition

What is the GMFM?

• The Gross Motor Function Measure (GMFM) is a clinical measure designed and validated

to evaluate changes in the gross motor function in children with cerebral palsy (CP).

• There are two versions of the GMFM: the original 88-item measure (GMFM-88) and

the 66-item measure (GMFM-66). These items are administered in the same way—the

difference between the two versions simply concerns which of the items (from the full

pool of 88 possible items) are included in GMFM-66.

• There are three methods of administering the GMFM to obtain a GMFM-66 score. All

three methods require the Gross Motor Ability Estimator (GMAE-2) scoring software to

convert the item data into a GMFM-66 score. Administration methods include the following:

(1) GMFM-66: administer all 66 items; (2) GMFM-66-Item Sets (GMFM-66-IS): use

a scoring algorithm to identify a subset of items to administer; and (3) GMFM-66 Basal &

Ceiling (GMFM-66-B&C): use a basal/ceiling approach to identify a subset of items.

Items on the GMFM-88 span aspects of what the World Health Organization’s International

Classification of Functioning, Disability and Health refers to as gross motor

‘activity’, ranging from activities such as lying and rolling to walking, running and

jumping skills. The GMFM-66 consists of a subset of the 88 items that has been shown to be unidimensional.