Table 1:
Characteristics of the Study Population by Surgical Site Infection
| SSI (n=1,756) | No SSI (n=52,477) | P Value | |
|---|---|---|---|
| Mean Age (SD) | 63.24 (10.76) | 62.98 (12.11) | 0.38 |
| Female Gender | 96 (5.47%) | 3,208 (6.11%) | 0.27 |
| Surgery Type | |||
| General | 888 (50.57%) | 14,576 (27.78%) | |
| Neurosurgery | 61 (3.47%) | 4,214 (8.03%) | |
| Orthopedic | 206 (11.73%) | 13,422 (25.58%) | |
| Peripheral Vascular | 355 (20.22%) | 7,462 (14.22%) | |
| Urology | 83 (4.73%) | 6,192 (11.80%) | |
| Oral Surgery | 2 (0.11%) | 108 (0.20%) | <0.01 |
| Otolaryngology | 43 (2.45%) | 1,708 (3.25%) | |
| Plastic Surgery | 37 (2.11%) | 811 (1.55%) | |
| Podiatry | 11 (0.63%) | 388 (0.74%) | |
| Thoracic Surgery | 44 (2.50%) | 2,707 (5.16%) | |
| Other | 26 (1.48%) | 889 (1.69%) | |
| Emergent Surgery | 219 (12.47%) | 5,209 (9.93%) | <0.01 |
| Pre-operative conditions | |||
| Alcohol use (>2 drinks per day) | 170 (9.68%) | 4,293 (8.18%) | 0.02 |
| History of diabetes | 301 (17.14%) | 6,228 (11.87%) | <0.01 |
| History of chronic obstructive pulmonary disease | 354 (20.16%) | 8,230 (15.68%) | <0.01 |
| History of rest pain/Gangrene | 201 (11.45%) | 2,773 (5.28%) | <0.01 |
| History of myocardial infarction | 15 (0.85%) | 393 (0.75%) | 0.62 |
| Sepsis in 48 hours prior to surgery | 58 (3.30%) | 1,451 (2.77%) | 0.18 |
| Current pneumonia | 12 (0.68%) | 489 (0.93%) | 0.28 |
| Weight Lossa | 103 (5.87%) | 2,057 (3.92%) | <0.01 |
| History of angina in 30 days prior to surgery | 36 (2.05%) | 711 (1.35%) | 0.01 |
| Bleeding Disorder | 141 (8.03%) | 3,561 (6.79%) | 0.04 |
| Congestive heart failure in 30 days prior to surgery | 33 (1.88%) | 603 (1.15%) | <0.01 |
| Steroid use in 30 days prior to surgery | 44 (2.51%) | 1,264 (2.41%) | 0.79 |
| Acute renal failure | 12 (0.68%) | 364 (0.69%) | 0.96 |
| Dialysis in 2 weeks prior to surgery | 32 (1.82%) | 1,061 (2.02%) | 0.56 |
| Ventilator dependent in 48 hours prior to surgery | 10 (0.57%) | 428 (0.82%) | 0.25 |
| Ascites | 16 (0.91%) | 445 (0.85%) | 0.78 |
| Preoperative Laboratory Tests | |||
| Mean hematocrit, % (SD) | 38.66 (6.02) | 39.36 (5.91) | <0.01 |
| Mean serum albumin, g/dl (SD) | 3.68 (0.75) | 3.77 (0.97) | <0.01 |
| Mean White Blood Count (WBC), X 1000/mm3 (SD) | 8.62 (3.75) | 8.31 (4.35) | <0.01 |
| Mean Blood Urea Nitrogen (BUN), mg/dl (SD) | 17.34 (10.60) | 17.79 (10.66) | 0.09 |
| Mean Partial thromboplastin time, seconds (SD) | 32.01 (11.14) | 31.19 (8.97) | <0.01 |
| Mean bilirubin, mg/dl (SD) | 0.73 (0.65) | 0.75 (0.93) | 0.34 |
| ASA Class | |||
| 1–2 | 247 (14.07%) | 10,590 (20.18%) | |
| 3 | 1,180 (67.24%) | 34,411 (65.58%) | <0.01 |
| 4–5 | 328 (18.69%) | 7,470 (14.24%) | |
| Wound Classification | |||
| Clean | 634 (36.10%) | 28,888 (55.05%) | |
| Clean/Contaminated | 794 (45.22%) | 17,161 (32.70%) | <0.01 |
| Contaminated | 183 (10.42%) | 2,874 (5.48%) | |
| Dirty/Infected | 145 (8.26%) | 3,554 (6.77%) |
a
Loss of >10% body weight in last six months
b
All of the variables in Table 1 were assessed for inclusion in the multivariable model