Table 2.

PROMIS-PF items and parameters

PROMIS Physical Functioning Item	Item Wording	IRT Parametersa,b
		Slope	Threshold 1	Threshold 2	Threshold 3	Threshold 4
Lower Extremity
PFA23	Are you able to go for a walk of at least 15 min?	4.28753	− 1.9146	− 1.5792	− 1.1944	− 0.6814
PFA21	Are you able to go up and down stairs at a normal pace?	4.23685	−1.885	−1.4805	− 1.0464	− 0.3953
PFA10	Are you able to stand for one hour?	3.37529	−1.7469	−1.3522	− 0.9182	− 0.3361
PFA3	Does your health now limit you in bending, kneeling, or stooping?	2.94958	−2.25	−1.2635	− 0.563	0.029
PFA42	Are you able to carry a laundry basket up a flight of stairs?	4.39902	−1.8357	−1.4509	− 1.0267	− 0.4249
PFB1	Does your health now limit you in doing moderate work around the house like vacuuming, sweeping floors or carrying in groceries?	4.38889	−2.4474	−1.6384	−1.076	−0.632
PFA5	Does your health now limit you in lifting or carrying groceries?	4.13549	−2.3684	−1.6186	−1.0365	−0.5334
PFA12	Are you able to push open a heavy door?	3.45638	−2.7039	−2.0429	−1.52	−0.7504
PFA14r1	Are you able to carry a heavy object (over 10 pounds/5 kg)?	3.43	−2.21	−1.74	−1.25	−0.66
PFB54	Does your health now limit you in going OUTSIDE the home, for example to shop or visit a doctor’s office?	3.39556	−3.286	−2.2698	−1.6877	−1.1944
PFA16r1	Are you able to dress yourself, including tying shoelaces and buttoning up your clothes?	3.37	−3.14	−2.56	−1.91	−1.24
PF4	Does your health now limit you in doing heavy work around the house like scrubbing floors, or lifting or moving heavy furniture?	4.39902	−1.5594	−0.9773	−0.4150	0.0586
PFA13	Are you able to exercise for an hour?	2.95971	−1.4114	−0.9872	−0.415	0.3052

^aSlope aka “discrimination” refers to the ability of the item to differentiate between different levels of the latent trait. Generally, the higher the discrimination the better the item as it indicates that people with a higher latent trait are much more likely to respond in the higher category

^bThreshold in the Graded Response Model describes the level of the latent trait at which the person with that latent trait is more likely to respond in the higher category than in the lower category. i.e. Threshold 1 – the level of the latent trait at which the person is likely to respond 1 (or higher) vs. 0; Threshold 2 – the level of the latent trait at which the person is likely to respond 2 (or higher) vs. 1; Threshold 3 – the level of the latent trait at which the person is likely to respond 3 (or higher) vs. 2 and Threshold 4 – the level of the latent trait at which the person is likely to respond 4 vs. 3. There are no responses higher than 4 possible for 5-category items with item scores ranging from 0 to 4. Generally, while a wider spread of thresholds for individual item is desirable, a mixture of threshold levels across the whole instrument is best