Table 2 Characteristics of the study population at baseline and one-year follow-up after TKA.

From: Acute surgical site infection after total knee arthroplasty in patients with rheumatoid arthritis versus osteoarthritis

 

Original data

After 1:3 PS matching

RA (n = 887)

OA (n = 48,818)

p-value

SMD

RA (n = 842)

OA (n = 2526)

p-value

SMD

PS

0.05 ± 0.06

0.02 ± 0.02

 < 0.001

0.671

0.03 ± 0.03

0.03 ± 0.03

0.1

 < 0.001

Age

64.93 ± 10.11

70.82 ± 8.18

 < 0.001

0.641

65.75 ± 9.4

65.6 ± 9.25

0.673

0.016

Sex

Male

139 (15.67)

12,589 (25.81)

 < 0.001

0.252

137 (16.27)

426 (16.86)

0.689

0.016

Female

748 (84.33)

36,186 (74.19)

705 (83.73)

2100 (83.14)

Operation year

2012

204 (18.12)

10,371 (16.41)

0.445

0.045

190 (22.57)

559 (22.13)

0.939

0.011

2013

346 (30.73)

19,379 (30.66)

0.001

329 (39.07)

982 (38.88)

0.004

2014

337 (29.93)

19,068 (30.16)

0.005

323 (38.36)

985 (38.99)

0.013

Comorbidity

Hypertension

359 (40.47)

29,015 (59.44)

 < 0.001

0.386

358 (42.52)

1100 (43.55)

0.602

0.021

Diabetes mellitus

106 (11.95)

12,269 (25.13)

 < 0.001

0.344

105 (12.47)

359 (14.21)

0.204

0.051

Hyperlipidemia

113 (12.74)

12,260 (25.11)

 < 0.001

0.32

113 (13.42)

371 (14.69)

0.364

0.037

COPD

74 (8.34)

3581 (7.34)

0.255

0.037

70 (8.31)

202 (8)

0.77

0.011

UTI

20 (2.25)

1594 (3.27)

0.093

0.062

19 (2.26)

59 (2.34)

0.895

0.005

CHF

20 (2.25)

1373 (2.81)

0.319

0.036

19 (2.26)

35 (1.39)

0.081

0.065

Cancer

64 (7.22)

3582 (7.34)

0.89

0.005

62 (7.36)

163 (6.45)

0.36

0.036

CRD

17 (1.92)

1596 (3.27)

0.024

0.085

16 (1.9)

64 (2.53)

0.296

0.043

Peripheral vascular disease

6 (0.68)

392 (0.8)

0.675

0.014

6 (0.71)

11 (0.44)

0.397

0.036

Anemia

50 (5.64)

692 (1.42)

 < 0.001

0.23

18 (2.14)

84 (3.33)

0.082

0.073

Valvular heart disease

18 (2.03)

1313 (2.69)

0.227

0.044

18 (2.14)

40 (1.58)

0.284

0.042

Ischemic heart disease

61 (6.88)

6906 (14.15)

 < 0.001

0.239

59 (7.01)

167 (6.61)

0.691

0.016

Hospital level

Medical center

386 (46.01)

14,262 (33.15)

 < 0.001

 

358 (45.03)

711 (31.32)

 < 0.001

 

Regional hospital

270 (32.18)

16,036 (37.27)

 

262 (32.96)

852 (37.53)

 

Local hospital

183 (21.81)

12,727 (29.58)

 

175 (22.01)

707 (31.15)

 

Length of stay (days)

6.77 ± 2.27

6.76 ± 2.32

0.904

 

6.77 ± 2.26

6.77 ± 2.11

0.986

 

Blood transfusion

448 (50.51)

20,714 (42.43)

 < 0.001

 

422 (50.12)

991 (39.23)

 < 0.001

 

Medications

NSAIDs

872 (98.31)

44,957 (92.09)

 < 0.001

 

828 (98.34)

2334 (92.4)

 < 0.001

 

Steroids

707 (79.71)

9731 (19.93)

 < 0.001

 

667 (79.22)

502 (19.87)

 < 0.001

 

DMARDs

809 (91.21)

N/A

  

765 (90.86)

N/A

  

anti-TNF-α

138 (15.56)

N/A

  

132 (15.68)

N/A

  

One-year infection

27 (3.04)

1420 (2.91)

0.812

 

17 (2.02)

75 (2.97)

0.143

 
  1. CI, confidence interval; CHF, congestive heart failure; COPD, chronic obstructive pulmonary disease; CRD, chronic renal disease; N/A, not applicable; NSAIDs, nonsteroidal anti-inflammatory drugs; OA, osteoarthritis; OR, odds ratio; PS, propensity score; RA, rheumatoid arthritis; SMD, standardized mean difference; UTI, urinary tract infection.
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