Relationship between biological factors and catastrophizing and clinical outcomes for female patients with knee osteoarthritis

Table 1 Characteristics of study subjects

Variables	n = 77
Age (yr)	72 (50-86)
BMI (kg/m2)	23.7 (14.5-41.7)
K-L grade (Rt + Lt)	5 (3-8)
PCS	20 (0-50)
Pain rating (VAS)	26 (0-99)
TUG (s)	6.0 (4.1-16.5)
JKOM	18 (1-81)

Data are shown as the median (range). BMI: Body mass index; K-L grade: Kellgren-Lawrence grading system; VAS: Visual analogue scale; TUG: Timed up and go test; JKOM: Japanese Knee Osteoarthritis Measure; PCS: Pain Catastrophizing Scale.

Table 2 Comparison of each outcome between unilateral and bilateral knee osteoarthritis

Variables	Unilateral (n = 17)	Bilateral (n = 60)	P-value
Pain rating (VAS)	24 (0-95)	26 (0-99)	0.51
TUG (s)	5.5 (4.4-7.2)	6.3 (4.1-16.5)	0.02
JKOM	13 (2-35)	18 (1-81)	0.23

Data are shown as the median (range). The Mann-Whitney U test was used to compare differences between two groups. VAS: Visual analogue scale; TUG: Timed up and go test; JKOM: Japanese Knee Osteoarthritis Measure.

Table 3 Spearman’s correlation coefficients between each variable

	Age	BMI	K-L grade	PCS	Pain rating	TUG	JKOM
Age	1.000	-0.144	0.100	-0.023	-0.079	0.170	-0.017
BMI		1.000	0.322b	0.084	0.212	0.257a	0.046
K-L grade			1.000	0.182d	0.281a	0.587d	0.467d
PCS				1.000	0.574d	0.404d	0.594d
Pain rating					1.000	0.487d	0.721d
TUG						1.000	0.588d
JKOM							1.000

Value (ρ): Correlation coefficient. Small letters show the statistical significance:

^aP < 0.05,

^bP < 0.01,

^dP < 0.001. BMI: Body mass index; K-L grade: Kellgren-Lawrence grading system; PCS: Pain Catastrophizing Scale; TUG: Timed up and go test; JKOM: Japanese Knee Osteoarthritis Measure.

Table 4 Multiple linear regression analysis of factors associated with each outcome

Outcome	Independent variables	R2	Unstandardized coefficients: B	95%CI for B	β	P-value
Pain rating		0.397
	BMI		0.162	0.039-0.284	0.239	0.010
	PCS		0.139	0.093-0.184	0.555	< 0.001
TUG		0.431
	K-L grade		0.638	0.419-0.856	0.52	< 0.001
	PCS		0.053	0.023-0.082	0.313	0.001
JKOM		0.492
	K-L grade		4.556	2.737-6.374	0.421	< 0.001
	PCS		0.719	0.470-0.968	0.485	< 0.001

TUG: Timed up and go test; JKOM: Japanese Knee Osteoarthritis Measure; BMI: Body mass index; K-L grade: Kellgren-Lawrence grading system; PCS: Pain Catastrophizing Scale.