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Table 3 Multivariable Weibull accelerated failure-time regression model assessing risk factors for seroconversion to C. burnetii before breeding.

From: A longitudinal study of serological responses to Coxiella burnetii and shedding at kidding among intensively-managed goats supports early use of vaccines

Variable

Levels

n

Serocon.

Coef.

SE (Coef.)

p value

Survival rate ratio (95% CI)

Hazard ratio (95% CI)

Cohort

Cohort 2

62

42

−0.60

0.11

0.001

0.55 (0.39, 0.78)

2.73 (1.45, 5.16)

Cohort 1

33

16

0.00 (ref)

  

1.00

1.00

Doe IgM

Positive

37

29

−0.42

0.16

0.008

0.65 (0.48, 0.89)

2.04 (1.19, 3.54)

Negative

56

28

0.00 (ref)

  

1.00

1.00

Intercept

3.89

0.35

< 0.001

  1. In intensively-reared goats in Victoria, Australia, 2014–2015. Interpretation: After adjusting for the effect of cohort, kids born by does that had positive IgM titres (Doe IgM = positive; indicating recent exposure) were 2.04 times more likely to seroconvert within the first 6 months of life compared to those born by IgM seronegative does. Log likelihood = −201.1. Coef. coefficient. Similarly, after adjusting for the effect of farm, kids born by does that had positive IgM titres were 2.23 times (95% CI 1.29, 3.86) more likely to seroconvert within the first 6 months of life compared to those born by IgM seronegative does; see Additional file 3