Table 5.
Risk factors from multivariable GLMM model for the incidence of bTB reactor status (number of animal = 1491; number of herds = 128; 2 missing on animal data)
| Risk factor | Class | % Positive | Multivariable final model | VIF (±s.e.) | |
|---|---|---|---|---|---|
| Adjusted OR (95%CI) | P value | ||||
| Intercept | 0.0 | <0.001 | |||
| Exposure time (year)a | <1.5 | 5 (45/892) | – | – | 1.46 (±1.2) |
| ⩾1.5 | 4 (24/599) | 1.2 (0.4, 4.2) | 0.761 | ||
| Age group (year) | ⩽1 | 2.6 (11/430) | – | – | 1.46 (±1.2) |
| >1 to ⩽3 | 2.1 (9/433) | 1 (0.3, 3.2) | 0.988 | ||
| >3 to ⩽5 | 6.4 (16/251) | 2 (0.7, 6.4) | 0.209 | ||
| >5 to ⩽7 | 9.8 (17/173) | 3.4 (1.1, 10.9) | 0.032 | ||
| >7 to ⩽18 | 7.4 (15/202) | 3.8 (1.2, 12.3) | 0.024 | ||
| Herd size | <60 | 2.1 (24/1135) | – | – | 1.01 (±1) |
| ⩾60 | 12.6 (45/356) | 7 (0.8, 134) | 0.106 | ||
| Herd riskb | 0 | 1.4 (14/975) | – | – | 1.02 (±1) |
| >0 to ⩽2.5% | 1.7 (4/230) | 2.3 (0.2, 43) | 0.527 | ||
| >2.5% | 17.5 (50/284) | 14.3 (2.7, 113) | 0.003 | ||
OR, odds ratio; VIF, variance inflation factor; s.e., standard error.
a
Exposure time refers to the time period the animals/herds were followed.
b
Herd risk was categorised based on the within-herd apparent prevalence according to the SICCT test status from the 2016/17 survey (category 1: herds with 0 apparent prevalence, category 2: herds with apparent prevalence between 0% and 2.5%, category 3: herds with apparent prevalence of >2.5%).