Table 2. Results of model building in a study of the effects of culling on Leptospira interrogans carriage by rats, Vancouver, British Columbia, Canada, June 2016–January 2017.
| Covariate |
Unadjusted odds ratio* (95% CI) |
Adjusted odds ratio† (95% CI) |
p value |
| Season | |||
| Summer | Reference | –‡ | – |
| Fall | 0.44 (0.13–1.39) | – | – |
| Winter |
0.87 (0.22–3.24) |
– |
– |
| Sex | |||
| F | Reference | – | – |
| M |
1.28 (0.70–2.37) |
– |
– |
| Sexual maturity | |||
| Juvenile | Reference | – | – |
| Mature |
16.26 (6.28–51.95) |
– |
– |
| Continuous length, cm |
1.25 (1.18–1.35) |
– |
– |
| Wounds | |||
| No | Reference | Reference | |
| Yes |
1.81 (1.42–2.39) |
3.87 (1.73–9.12) |
0.0013 |
| Weight, g | |||
| <122 | Reference | Reference | |
|
>122 |
17.88 (7.22–53.28) |
9.98 (3.70–31.74) |
<10–4 |
| Intervention | |||
| Before intervention, all block types, n = 261 | Reference | Reference | |
| After intervention, control blocks, n = 97 | 0.69 (0.22–2.00) | 0.77 (0.22–2.58) | 0.68 |
| After intervention, nonkill flanking blocks, n = 33 | 1.50 (0.49–4.40) | 2.22 (0.65–7.47) | 0.19 |
| After intervention, intervention blocks, n = 39 | 8.67 (2.02–55.00) | 9.55 (1.75–78.31) | 0.016 |
*Bivariable relationships between the indicated covariate and L. interrogans status, while controlling for the random effect of the block. †Results of the final multivariable model in which the effect of each covariate is adjusted for other covariates in the model. ‡Dashes indicate variables not carried forward into the final multivariable model on the basis of statistical confounding criteria.