Table 3. Variables from the univariable analysis with p ≤ 0.2 (ranked by p-value).
| Variable | No. of infected farms n = 71* (%) | No. of non-infected farms n = 80 (%) | Odds Ratio (CI 95%) | p-value (Chi square) |
|---|---|---|---|---|
| Age of hens# | < 0.01 | |||
| till 40 weeks | 15/70 (21.4) | 32/77 (41.6) | Ref | Ref |
| 40–60 weeks | 28/70 (40.0) | 13/77 (16.9) | 4.6 (1.87–11.29) | < 0.01 |
| older than 60 weeks | 27/70 (38.6) | 32/77 (41.6) | 1.80 (0.81–4.00) | 0.15 |
| Use of bedding material | 64/69 (92.8) | 60/80 (75.0) | 4.27 (1.51–12.09) | <0.01 |
| Horses present | 26/71 (36.6) | 14/80 (17.5) | 2.72 (1.28–5.78) | <0.01 |
| Manure disposal# | 0.08 | |||
| once or less than once a week | 6/70 (8.6) | 18/77 (23.4) | Ref | Ref |
| once every two weeks | 21/70 (29.6) | 14/77 (18.3) | 4.50 (1.43–14.14) | 0.10 |
| once a month | 17/70 (23.9) | 18/77 (23.4) | 2.83 (0.91–8.83) | 0.07 |
| less than once a month | 26/70 (38.0) | 27/77 (35.1) | 8.89 (0.99–8.4) | 0.05 |
| Use of shower before entrance (visitors) | 6/71 (8.5) | 14/80 (17.5) | 0.44 (0.16–1.16) | 0.10 |
| Other birds presenti | 5/71 (7.0) | 1/80 (1.3) | 5.99 (0.68–52.5) | 0.10 |
| Vaccination against Pasteurella multocidai | 8/71 (11.3) | 3/80 (3.8) | 3.26 (0.83–12.80) | 0.12 |
| Vacancy periodii | / | 0.14 | ||
| Vaccination against Egg Drop Syndrome | 41/71 (57.7) | 37/80 (46.3) | 1.59 (0.83–3.02) | 0.16 |
| Free range sampled house | 39/69 (42.0) | 25/80 (31.3) | 1.60 (0.81–3.12) | 0.17 |
*Due to missing values, the number of farms per variable can differ
#p-value was calculated with logistic regression
iFisher exact p-value was used (cells with counts n<5)
iicontinuous variable