| 
 | Level of hospitalization | TOTAL | P-value | ||
| Category 1 | Category 2 | Category 3 | |||
| Presence of SSI | 
 | 
 | 
 | 
 | p = 0.02 | 
| YES | 0.0% (0) | 17.6% (6) | 39.5% (45) | 33.6% (51) | |
| NO | 100% (4) | 82.4% (28) | 60.5% (69) | 66.4% (101) | |
| TOTAL | 100% (4) | 100% (34) | 100% (114) | 100% (152) | |