Table 1 Characteristics of the study population at baseline and 90-day 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 = 1126)

OA (n = 63,215)

p-value

SMD

RA (n = 1066)

OA (n = 3198)

p-value

SMD

PS

0.05 ± 0.06

0.02 ± 0.02

 < 0.001

0.671

0.03 ± 0.03

0.03 ± 0.03

0.954

 < 0.001

Age

64.76 ± 10.24

70.87 ± 8.2

 < 0.001

0.689

65.71 ± 9.36

65.99 ± 9.3

0.389

0.03

Sex

Male

186 (16.52)

16,431 (26.02)

 < 0.001

0.234

183 (17.17)

554 (17.32)

0.91

0.004

Female

940 (83.48)

46,721 (73.98)

883 (82.83)

2644 (82.68)

Operation year

2012

204 (18.12)

10,371 (16.41)

0.368

0.045

190 (17.82)

555 (17.53)

0.65

0.008

2013

346 (30.73)

19,379 (30.66)

0.001

329 (30.86)

1000 (31.27)

0.009

2014

337 (29.93)

19,068 (30.16)

0.005

323 (30.30)

921 (28.8)

0.033

2015

239 (21.23)

14,397 (22.77)

0.037

224 (21.01)

722 (22.58)

0.038

Comorbidity

Hypertension

464 (41.21)

37,550 (59.40)

 < 0.001

0.37

462 (43.34)

1403 (43.87)

0.762

0.011

Diabetes mellitus

150 (13.32)

16,035 (25.37)

 < 0.001

0.309

149 (13.98)

461 (14.42)

0.724

0.013

Hyperlipidemia

148 (13.14)

16,093 (25.46)

 < 0.001

0.316

148 (13.88)

454 (14.20)

0.8

0.009

COPD

101 (8.97)

4604 (7.28)

0.031

0.062

97 (9.1)

270 (8.44)

0.508

0.023

UTI

24 (2.13)

2088 (3.30)

0.029

0.072

23 (2.16)

74 (2.31)

0.767

0.01

CHF

24 (2.13)

1761 (2.79)

0.185

0.043

23 (2.16)

66 (2.06)

0.853

0.007

Cancer

92 (8.17)

4724 (7.47)

0.378

0.026

87 (8.16)

267 (8.35)

0.848

0.007

CRD

29 (2.58)

2181 (3.45)

0.11

0.051

28 (2.63)

79 (2.47)

0.778

0.01

Peripheral vascular disease

6 (0.53)

518 (0.82)

0.289

0.035

6 (0.56)

22 (0.69)

0.662

0.017

Anemia

67 (5.95)

909 (1.44)

 < 0.001

0.241

27 (2.53)

141 (4.41)

0.006

0.103

Valvular heart disease

22 (1.95)

1676 (2.65)

0.148

0.047

22 (2.06)

55 (1.72)

0.465

0.025

Ischemic heart disease

79 (7.02)

8957 (14.17)

 < 0.001

0.234

78 (7.32)

227 (7.1)

0.81

0.009

Hospital level

Medical center

486 (45.89)

18,256 (33.09)

 < 0.001

 

450 (44.91)

956 (33.17)

 < 0.001

 

Regional hospital

350 (33.05)

20,496 (37.14)

 

338 (33.73)

1053 (36.54)

 

Local hospital

223 (21.06)

16,427 (29.77)

 

214 (21.36)

873 (30.29)

 

Length of stay (days)

6.66 ± 2.21

6.69 ± 2.38

0.611

 

6.67 ± 2.2

6.75 ± 2.6

0.335

 

Blood transfusion

559 (49.64)

26,177 (41.41)

 < 0.001

 

525 (49.25)

1220 (38.15)

 < 0.001

 

Medications

NSAIDs

1107 (98.31)

58,210 (92.08)

 < 0.001

 

1049 (98.41)

2923 (91.4)

 < 0.001

 

Steroids

901 (80.02)

12,809 (20.26)

 < 0.001

 

849 (79.64)

642 (20.08)

 < 0.001

 

DMARDs

1023 (90.85)

N/A

  

970 (90.99)

N/A

  

anti-TNF-α

178 (15.81)

N/A

  

167 (15.67)

N/A

  

90-day infection

29 (2.58)

1680 (2.66)

0.865

 

27 (2.53)

102 (3.19)

0.278

 
  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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