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Table 5 Multivariable multilevel negative binomial regression model examining seasonal and annual variability in monthly pneumonic lung condemnations for three sentinel selection approaches

From: Suitability of sentinel abattoirs for syndromic surveillance using provincially inspected bovine abattoir condemnation data

Model IRR 95% CI P-value
a) Full dataset 1
Winter --- ---- ---
Spring 0.97 0.85 – 1.11 0.61
Summer 0.90 0.78 – 1.03 0.12
Fall 0.89 0.78 – 1.03 0.11
2001 --- --- ---
2002 0.93 0.79 – 1.08 0.34
2003 0.99 0.85 – 1.16 0.93
2004 0.53 0.44 – 0.63 <0.01
2005 0.45 0.38 – 0.54 <0.01
2006 0.39 0.32 – 0.47 <0.01
2007 0.32 0.26 – 0.40 <0.01
Calves --- --- ---
Cows 1.05 0.87 – 1.27 0.60
Heifers 0.68 0.57 – 0.80 <0.01
Steers 0.75 0.66 – 0.85 <0.01
b) Abattoirs open all weeks 2
Winter --- --- ---
Spring 1.01 0.88 – 1.16 0.93
Summer 0.92 0.80 – 1.05 0.22
Fall 0.91 0.79 – 1.05 0.22
2001 --- --- ---
2002 0.94 0.80 – 1.11 0.50
2003 1.03 0.88 – 1.21 0.68
2004 0.57 0.48 – 0.68 <0.01
2005 0.46 0.38 – 0.55 <0.01
2006 0.40 0.38 – 0.49 <0.01
2007 0.34 0.28 – 0.42 <0.01
Calves --- --- ---
Cows 1.03 0.84 – 1.26 0.75
Heifers 0.73 0.62 – 0.87 <0.01
Steers 0.75 0.66 – 0.86 <0.01
c) Multi-criteria 3
Winter --- --- ---
Spring 1.08 0.92 – 1.28 0.33
Summer 0.95 0.80 – 1.12 0.51
Fall 0.92 0.78- 1.09 0.35
2001 --- --- ---
2002 1.03 0.84 – 1.27 0.76
2003 1.30 1.11 – 1.63 <0.01
2004 1.04 0.85 – 1.28 0.72
2005 0.67 0.54 – 0.84 <0.01
2006 0.67 0.49 – 0.79 <0.01
2007 0.62 0.62 – 0.96 <0.01
Calves --- --- ---
Cows 0.77 0.62 – 0.96 0.02
Heifers 0.62 0.51 – 0.75 <0.01
Steers 0.71 0.61 – 0.82 <0.01
d) Large abattoirs 4
Winter --- --- ---
Spring 0.97 0.82 – 1.15 0.74
Summer 0.92 0.77 – 1.09 0.32
Fall 0.99 0.84 – 1.18 0.94
2001 --- --- ---
2002 1.38 1.11 – 1.72 <0.01
2003 1.56 1.26 – 1.93 <0.01
2004 0.97 0.77 – 1.22 0.78
2005 0.75 0.59 – 0.94 0.01
2006 0.64 0.50 – 0.82 <0.01
2007 0.64 0.50 – 0.82 <0.01
Calves --- --- ---
Cows 1.22 0.92 – 1.62 0.16
Heifers 1.02 0.83 – 1.25 0.86
Steers 0.87 0.74 – 1.03 0.10
  1. 1Abattoirs processing at least 1 bovine carcass each year of study period (2001 – 2007).
  2. 2Abattoirs processing at least 1 bovine carcass 52 weeks per year.
  3. 3Selection of abattoirs meeting the following criteria: processed at least 499 cattle per year, processed at least 1 bovine carcass 44 weeks or more per year, processed cattle representing all animal classes (calves, cows, heifers and steers).
  4. 4Abattoirs processing ≥ 6500 cattle per year.