Table 1.
Effect of time, extra- versus intraluminal location, and axial location on number of colony forming units (CFU) in urinary catheters
| ndf | ddf | F | P | |
|---|---|---|---|---|
| Fixed effects | ||||
| Time |
1 |
6 |
3.69 |
0.1033 |
| Surface |
1 |
46 |
0.02 |
0.8952 |
| Axial location |
1 |
46 |
14.69 |
0.0004*** |
| Surface × time |
1 |
46 |
0.03 |
0.8682 |
| Surface × axial location |
1 |
46 |
3.95 |
0.0528† |
| |
|
df |
LR statistic |
P |
| Random effects | ||||
| Subject, intercept | 0, 1 | 20.6 | <0.0001*** | |
Axial location was modeled as a continuous variable (bladder = 1,deep urethral = 2, superficial urethral = 3, external = 4 for males and bladder = 1, urethral = 2.5, and external = 4 for females). The significance of random effect (subject) and the proper covariance structure for the repeated measures were tested using likelihood ratio tests. Ndf is numerator degrees of freedom, ddf is denominator degrees of freedom. Urinary catheters from 5 males and 3 females catheterized in a level 1 trauma center for 1 to 16 days.
*** is p <0.001 and †p <0.10.