Using item response theory to enrich and expand the PROMIS® pediatric self report banks

Table 1 The number of items in each of seven PROMIS pediatric item pools, the number of new items considered for addition, and the disposition of the new items

	Number of items
Domain	Original item pool	New items considered	New items after dimensionality analysis	New items after DIF analysis and calibration	Enlarged item pool
Anger	6	5	5	4	9^†
Anxiety	15	5	3	2	15^††
Depressive symptoms	14	1	1	1	14^†††
Pain interference	13	7	7	7	20
Fatigue	23	2	2	2	25
Physical functioning: upper extremity	29	5	5*	5	34
Physical functioning: Mobility	26	3	3	1	27

^†One item was removed from the original Anger item pool due to conflicting copyright claims.
^††Two items were removed from the original Anxiety item pool due to conflicting copyright claims.
^†††One item was removed from the original Depressive Symptoms item pool due to conflicting copyright claims.
*Two new items exhibited LD, but were retained as “enemy items” to expand the range of the scale for those with higher physical functioning.

ISSN: 1477-7525