Table 2. Correlation between age, state, farm type or production system, and influenza A virus status in swine in coordinated production systems, United States, September 2012–September 2013*.
| Factor | aOR (95% CI) | p value |
|---|---|---|
| Age group |
|
|
| Piglet vs. gilt |
1.3 (1.1–1.6) |
0.004 |
| State |
|
|
| Illinois vs. Oklahoma |
1.9 (1.4–2.6) |
<0.001 |
| Farm type | ||
| MF piglets vs. BTW | 0.7 (0.5–0.9) | 0.011 |
| GDU vs. BTW |
1.6 (1.2–2.1) |
<0.001 |
| System number |
|
|
| 2 vs. 1 | 1.7 (1.3–2.3) | <0.001 |
*Only statistically significant factors are shown; full analysis is provided in the Technical Appendix. aOR, adjusted odds ratio; CI, confidence interval; MF, multiplier farm; GDU, gilt development unit; BTW, breed-to-wean.