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Table 2 Distribution characteristics of covariates in TKA patients before and after propensity score matching in Anemia group and Non-Anemia group

From: Anemia and formation of deep vein thrombosis before operation in patients with knee osteoarthritis: a cross-sectional study

Covariates

Before matching

Ļ‡2

P Value

After matching

Ļ‡2

P Value

Anemia

Non-Anemia

Anemia

Non-Anemia

(Nā€‰=ā€‰342)

(Nā€‰=ā€‰663)

(Nā€‰=ā€‰310)

(Nā€‰=ā€‰310)

Gender

Male

74

21.64%

134

20.21%

0.28

0.00

68

21.94%

76

24.52%

0.579

0.253

Female

268

78.36%

529

79.79%

Ā Ā 

242

78.06%

234

75.48%

Ā Ā 

Age group(y)

ā€‰ā‰¤ā€‰60

40

11.70%

113

17.04%

13.53

0.01

32

10.32%

30

9.68%

0.133

0.717

60ā€“70

134

39.18%

301

45.40%

Ā Ā 

127

40.97%

125

40.32%

Ā Ā 

ā€‰>ā€‰70

168

49.12%

249

37.56%

Ā Ā 

151

48.71%

155

50.00%

Ā Ā 

BMI (kg/m2)

ā€‰<ā€‰18.5

11

3.22%

4

0.60%

15.49

0.00

3

0.97%

8

2.58%

2.459

0.483

18.5ā€“24.9

176

51.46%

309

46.61%

Ā Ā 

162

52.26%

156

50.32%

Ā Ā 

25ā€“29.9

125

36.55%

264

39.82%

Ā Ā 

117

37.74%

116

37.42%

Ā Ā 

ā€‰ā‰„ā€‰30

30

8.77%

86

12.97%

Ā Ā 

28

9.03%

30

9.68%

Ā Ā 

ABO blood type

type A

113

33.04%

228

34.39%

2.242

0.524

30

9.68%

32

10.32%

0.133

0.936

type B

78

22.81%

166

25.04%

Ā Ā 

125

40.32%

127

40.97%

Ā Ā 

type AB

31

9.06%

45

6.79%

Ā Ā 

155

50.00%

151

48.71%

Ā Ā 

type O

120

35.09%

224

33.79%

Ā Ā Ā Ā Ā Ā Ā Ā 

Hypertension

Yes

123

35.96%

268

40.42%

1.886

0.096

113

36.45%

119

38.39%

0.248

0.678

No

219

64.06%

395

59.58%

Ā Ā 

197

63.55%

191

61.61%

Ā Ā 

DM

Yes

37

10.82%

101

15.23%

3.71

0.032

38

12.26%

33

10.65%

Ā Ā 

No

305

89.18%

562

84.77%

Ā Ā 

272

87.74%

277

89.35%

Ā Ā 

CHD

Yes

26

7.60%

38

5.73%

1.324

0.155

22

7.10%

26

8.39%

0.364

0.653

No

316

92.40%

625

94.27%

Ā Ā 

288

92.90%

284

91.61%

Ā Ā 

History of major surgery in the last 12Ā months

Yes

12

3.51%

19

2.87%

0.312

0.351

9

2.90%

8

2.58%

0.06

0.5

No

330

96.49%

644

97.13%

Ā Ā 

301

97.10%

302

97.42%

Ā Ā 

ChronicĀ bronchitis

Yes

6

1.75%

7

1.06%

0.862

0.258

5

1.61%

5

1.61%

1

0.624

No

336

98.25%

656

98.94%

Ā Ā 

305

98.39%

305

98.39%

Ā Ā 

Cerebral infarction

Yes

11

3.22%

12

1.81%

1.996

0.118

9

2.90%

8

2.58%

0

1

No

331

96.78%

651

98.19%

Ā Ā 

301

97.10%

302

97.42%

Ā Ā 

Classification of OA

RA

37

10.82%

16

2.41%

31.909

0.001

16

5.16%

16

5.16%

0

1

OA

305

89.18%

647

97.59%

Ā Ā 

294

94.84%

294

94.84%

Ā Ā 

History of drinking

Yes

4

1.17%

24

3.62%

5.001

0.016

4

1.29%

6

1.94%

0.84

0.5

No

338

98.93%

639

96.38%

Ā Ā 

306

98.71%

304

98.06%

Ā Ā 

History of Smoking

Yes

13

3.80%

29

4.37%

0.185

0.402

11

3.55%

11

3.55%

0

1

No

329

96.20%

634

95.63%

Ā Ā 

299

96.45%

299

96.45%

Ā Ā 

Renal failure

Yes

6

1.75%

0

0.00%

11.701

0.002

0

0.00%

0

0.00%

*

*

No

336

98.25%

663

100%

Ā Ā 

310

0.00%

310

0.00%

Ā Ā 

Use of corticosteroids

Yes

15

4.59%

3

0.45%

19.85

0

2

0.65%

3

0.97%

0.2

0.5

No

327

95.61%

660

95.55%

Ā Ā 

308

99.35%

307

99.03%

Ā Ā 

History of cancer

Yes

3

0.88%

6

0.90%

0.002

0.633

3

0.97%

4

1.29%

0.144

1

No

339

99.12%

657

99.10%

Ā Ā 

307

99.03%

306

98.71%

Ā Ā 

COPD

Yes

4

1.17%

14

2.11%

1.138

0.21

22

7.10%

26

8.39%

0.36

0.65

No

338

98.83%

649

97.89%

Ā Ā 

288

92.90%

284

91.61%

Ā Ā 
  1. BMIā€”body mass index; DMā€”diabetes mellitus; CHDā€”coronary heart disease; OAā€”osteoarthritis; COPDā€”chronic obstructive pulmonary disease; DVTā€”deep vein thrombosis
  2. Pā€‰<ā€‰0.05 was considered statistically significant