Table 8.
Mixed effects linear regression of haemagglutination inhibition GMT of immunogen H1N1pdm09 in positive pig herds (n = 3,678 observations) in 1,048 unique pig farms (random effects)
| GMT (herd level) | |||||
|---|---|---|---|---|---|
| Predictors | Coefficients | SE | P values | 95% CI | |
| Year | |||||
| 2009 | Reference | ||||
| 2010 | −57.21 | 182.48 | 0.754 | −414.87 | 300.45 |
| 2011 | 252.96 | 178.57 | 0.157 | −97.02 | 602.94 |
| 2012 | 309.57 | 178.25 | 0.082 | −39.80 | 658.95 |
| 2013 | 40.98 | 178.38 | 0.818 | −308.63 | 390.60 |
| 2014 | 14.08 | 179.18 | 0.937 | −337.11 | 365.28 |
| 2015 | 30.02 | 179.39 | 0.867 | −321.58 | 381.62 |
| 2016 | 47.68 | 179.58 | 0.791 | −304.28 | 399.65 |
| 2017 | 205.65 | 182.47 | 0.26 | −151.99 | 563.29 |
| Production | |||||
| Fattening herds | Reference | ||||
| Sow herds | 163.27 | 63.86 | 0.011 | 38.11 | 288.43 |
| Number of positive pigs | −67.90 | 9.3172 | <0.001 | −86.16 | −49.64 |
| Proportion tested pigs positive | 629.07 | 77.856 | <0.001 | 476.48 | 781.67 |
| Constant | −216.54 | 199.75 | 0.278 | −608.05 | 174.96 |
Pigs in the herd with HAIT titre ≥40 were positive.
Categorical predictors: Production. Ordinal predictors: Year. Continuous predictors: Number of positive pigs and Proportion pigs positive.