Patient-Reported Outcomes Measurement Information System (PROMIS) instruments among individuals with symptomatic knee osteoarthritis: a cross-sectional study of floor/ceiling effects and construct validity

Table 2 Descriptive statistics of outcome measures in patients with knee osteoarthritis including floor and ceiling effects

Outcome Measure	Scores				Floor		Ceiling
Outcome Measure	Score Range	n	Mean ± SD	Median (range)	n	%	n	%
PROMIS Pain Interference	41-78.3	204	58.0 (7.0)	58.1 (41.0-74.4)	11	5.4	0	0
PROMIS Physical Function^a	14.1-61.7	204	40.7 (5.5)	40.2 (28.8-61.7)	0	0	1	0.5
PROMIS Anxiety	36.3-82.7	203	50.2 (8.9)	51.3 (36.3-72.9)	34	16.8	0	0
PROMIS Depression	37.1-81.1	202	48.9 (8.9)	48.2 (37.1-77.9)	49	24.3	0	0
SF-36 PCS^a	0-100	204	36.6 (9.1)	36.7 (14.0-59.8)	0	0	0	0
SF-36 MCS^a	0-100	204	52.5 (9.2)	54.5 (21.6-68.1)	0	0	0	0
SF-36 Bodily Pain^a	0-100	204	47.5 (18.6)	41.0 (0.0-100.0)	1	0.5	4	2.0
SF-36 Physical Function	0-100	204	52.0 (22.2)	50.0 (0.0-100.0)	2	1.0	3	1.5
WOMAC Pain	0-500	203	254 (98.6)	239.8 (50.7-500.0)	n/a	n/a	1	0.5
WOMAC Function	0-1700	204	899.0 (352.4)	906.7 (218.6, 1700.0)	0	0	1	0.5
6-min Walk Test^a^b (meters)	n/a	199	395.5 (90.1)	392.8 (89.1-645.3)	n/a	n/a	n/a	n/a
20-Meter Walk Test^a (seconds)	n/a	202	19.0 (5.3)	18.2 (9.6-66.8)	n/a	n/a	n/a	n/a
PSS	0-40	203	13.3 (7.0)	13.0 (0.0, 37.0)	5	2.5	0	0
BDI-II	0-63	199	7.6 (8.6)	5.0 (0.0-39.0)	27	13.6	0	0

PROMIS = Patient Reported Outcomes Measurement Information System (reported as T-scores); SF-36 = Medical Outcomes Short Form-36, MCS = Mental Component Summary, PCS = Physical Component Summary, BP = Bodily Pain; WOMAC = Western Ontario and McMaster Universities Arthritic Index; PSS = Perceived Stress Scale; BDI-II = Beck Depression Index II
^aHigher scores indicate better health-related outcomes (for other measures, higher scores indicates worse health-related outcomes)
^bDoes not include patients who refused, or attempted and failed