Table 2 Patient characteristics and leptin responses in cartilage cultures in the whole study population and compared across body mass index subgroups

Gender (female/male)^a

0.072

Body mass index (kg/m²)^b

30.9

(6.1)

26.2

(2.4)

35.7

(4.6)

<0.001

Age (years)^b

69.8

(10.0)

72.8

(9.7)

66.8

(9.4)

0.003

Synovial fluid leptin (ng/ml)^{c, d}

12.8

(17.8)

7.6

(11.0)

21.5

(26.7)

<0.001

Synovial fluid IL-6 (pg/ml)^{c, d}

118.9

(196.0)

126.8

(204.3)

114.0

(280.2)

0.784

Synovial fluid MMP-1 (ng/ml)^{c, d}

14.4

(25.7)

10.4

(16.6)

18.1

(27.3)

0.325

Synovial fluid MMP-3 (ng/ml)^{c, d}

649.5

(929.6)

591.6

(571.0)

764.9

(1159.0)

0.106

Leptin response in cartilage

MMP-1 (change pg/mg cartilage)^c

145.8

(247.1)

123.2

(253.6)

150.0

(258.3)

0.773

MMP-3 (change ng/mg cartilage)^c

5.2

(8.8)

6.0

(8.6)

4.9

(10.2)

0.920

MMP-13 (change pg/mg cartilage)^c

5.8

(13.6)

6.3

(11.8)

5.4

(15.9)

0.983

IL-6 (change pg/mg cartilage)^c

123.2

(310.2)

114.6

(295.1)

130.9

(312.0)

0.740

NO (change pmol/mg cartilage)^c

44.5

(133.4)

31.0

(125.8)

52.2

(140.0)

0.359

iNOS (fold of increase)^{c, e}

11.7

(160.6)

5.4

(143.1)

15.2

(209.6)

0.501

COX-2 (fold of increase)^{c, e}

6.9

(18.4)

7.1

(15.0)

6.4

(22.6)

0.748