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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.