Validation of the Questionnaire to Identify Knee Symptoms (QuIKS) using Rasch analysis

Table 1 Sample characteristics by study groups

Characteristics	Known groups
	Healthy knees, n = 55	Knee pain, n = 111	Knee osteoarthritis (pre-HTO), n = 34	Knee pain and pre-HTO, n = 145
Age, years
Mean (SD)	24.7 (4.4)	52.1 (6.8)	48.9 (6.5)	51.3 (6.8)
Sex
Female (%)	35 (63.6)	62 (55.4)^a	9 (36.0)	71 (49.0)
BMI, kg/m²
Mean (SD)	22.9 (3.1)	28.1 (9.1)	29.1 (4.7)	28.3 (8.3)
Affected knee
Unilateral (%)	1 (1.8)	61 (55.0)	18 (52.9)	79 (54.5)
Bilateral (%)	4 (7.3)	49 (44.1)	16 (47.1)	65 (44.8)
None (%)	50 (90.0)	1 (0.9)	0	1 (0.7)
Family history of arthritis
Yes (%)	23 (42.6)^a	52 (46.8)^a	11 (33.3)^a	63 (43.4)^b
History of knee injury
Yes (%)	3 (5.5)	77 (69.4)^c	23 (71.9)^b	100 (69.0)^d
History of knee pain
Yes (%)	2 (3.6)	51 (45.9)	32 (100)^b	83 (57.2)^e
Kellgren and Lawrence Grade, Number of knees with Grade 0/1/2/3/4	--	--	0/10/20/11/4	--
KOOS, range = 0–100 (worst to best state), median (IQR)
Other symptoms	100 (7.1)	53.6 (19.6)	37.5 (29.5)	53.6 (21.4)
Pain	100 (2.8)	80.6 (27.8)	48.6 (23.6)	72.2 (30.6)
ADL	100 (0)	89.7 (23.2)	58.8 (27.7)	80.9 (29.4)
Sport & Recreation	100 (0)	75.0 (40.0)	17.5 (39.1)	58.0 (50.0)
QOL	100 (0)	68.8 (31.3)	15.6 (31.3)	56.3 (43.8)

Kellgren and Lawrence grade severity: 0 (normal) is no OA; 1 (doubtful) is possible joint space narrowing and osteophytes, 2 (minimal) is definite joint space narrowing and osteophyte, 3 (moderate) is definite joint space narrowing, multiple osteophytes, some sclerosis and possible bone contour deformity, 4 (severe) is marked joint space narrowing, large osteophytes, severe sclerosis and definite bone contour deformity [20]
BMI body mass index, KOOS knee injury and osteoarthritis outcome score, ADL activities of daily living, QOL quality of life, IQR inter-quartile range
Missing data ^a n = 1, ^b n = 3, ^c n = 4, ^d n = 9, ^e n = 2

ISSN: 1477-7525