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Table 3 Comparison of patients with post-operative Staphylococcus aureus infection and uninfected patients following orthopedic surgical procedures*

From: Staphylococcus aureus infections following knee and hip prosthesis insertion procedures

  Prosthetic Knee Insertion Prosthetic Hip Insertion
  S. aureus infection Uninfected S. aureus infection Uninfected
  (N=48) (N=8,340) (N=44) (N=5,168)
NHSN risk index     
0 5 (10) 2,395 (29) 1 ( 2) 1,170 (23)
1 19 (40) 4,268 (51) 23 (52) 2,916 (56)
≥2 22 (46) 1,311 (16) 18 (41) 947 (18)
Missing 2 ( 4) 366 ( 4) 2 ( 5) 135 ( 3)
p-value <0.0001 0.0001
ASA score     
1: Healthy 1 ( 2) 599 ( 7) 0 ( 0) 131 ( 2)
2: Mild systemic disease 12 (25) 3,595 (43) 8 (18) 2,133 (41)
3: Severe systemic disease 28 (58) 3,790 (45) 28 (64) 2,359 (46)
4: Incapacitating disease 7 (15) 311 ( 4) 7 (16) 506 (10)
5: Dying 0 ( 0) 0 ( 0) 0 ( 0) 1 (<1)
6: Emergency care 0 ( 0) 0 ( 0) 0 ( 0) 0 ( 0)
Missing 0 ( 0) 45 (<1) 1 ( 2) 38 ( 1)
p -value 0.0002 0.024
Wound class     
Clean 47 (98) 8,042 (96) 43 (98) 4,927 (95)
Clean - contaminated 1 ( 2) 298 ( 4) 1 ( 2) 241 ( 5)
p -value 0.58 0.45
Procedure duration
Mean (SD), minutes 158.2 (108.1) 124.7 (110.0) 169.3 (112.8) 125.5 (109.6)
p -value 0.036 0.0082
Age category (years)     
18-29 1 ( 2) 393 ( 5) 1 ( 2) 77 ( 1)
30-39 2 ( 4) 418 ( 5) 1 ( 2) 203 ( 4)
40-49 8 (17) 793 ( 9) 4 ( 9) 598 (12)
50-59 12 (25) 1,752 (21) 7 (16) 883 (17)
60-69 9 (19) 2,318 (28) 8 (18) 1,060 (20)
70-79 11 (23) 2,039 (24) 6 (14) 1,250 (24)
80+ 5 (10) 627 ( 7) 17 (39) 1,097 (21)
p -value 0.46 0.17
  1. *Data shown as n (%) of patients, unless otherwise indicated.