Table 3—

Friedman staging system

Stage	Tongue position^#	Tonsil size^#	BMI kg·m⁻²
I	1 or 2	3, 4	<40
II	1 or 2	0, 1, 2	<40
	3 or 4	3, 4	<40
III	3	0, 1, 2	<40
	4	0, 1, 2	<40
IV	1, 2, 3, 4	0, 1, 2, 3, 4	>40
	All patients with craniofacial or other anatomical deformities

Data modified from [32]. BMI: body mass index. ^#: increasing values indicate higher tongue positions and larger tonsil sizes, respectively.