UTI incidence in patients undergoing posterior arthrodesis with either <7, 7–12, or >12 levels fused.
| Matched Data | No. of Levels Fused | Pairwise Significance by No. of Levels Fused | ||||
| <7 | 7–12 | >12 | <7 vs 7–12 | <7 vs >12 | 7–12 vs >12 | |
| Total No. of procedures | 1787 | 1787 | 1787 | - | - | - |
| UTI contracted within: | ||||||
| 1 wk | 22 (1.2) | 20 (1.1) | 12 (0.7) | 0.876 | 0.12 | 0.21 |
| 1 mo | 36 (2.0) | 31 (1.7) | 47 (2.6) | 0.62 | 0.3 | 0.09 |
| 2 mo | 48 (2.7) | 39 (2.2) | 60 (3.6) | 0.4 | 0.3 | 0.04 |
| 3 mo | 64 (3.6) | 48 (2.7) | 70 (3.9) | 0.15 | 0.7 | 0.04 |
Abbreviation: UTI, urinary tract infection.
Note: The 3 sets of levels were matched for age and gender.