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

Table 4 Negative binomial regression models comparing monthly pneumonic lung condemnation rates for all abattoirs for each animal class with three methods of sentinel abattoir selection

Sentinel selection method	IRR	95% CI	P-value
a) Calves
Full dataset¹	---	---	---
Abattoirs open all weeks²	1.12	0.95 – 1.32	0.16
Multi-criteria³	0.90	0.76 – 1.06	0.21
Large abattoirs⁴	1.25	1.06 – 1.47	0.01
b) Cows
Full dataset¹	---	---	---
Abattoirs open all weeks²	2.08	1.49 – 2.91	<0.01
Multi-criteria³	2.06	1.47 – 2.89	<0.01
Large abattoirs⁴	3.83	2.73 – 5.38	<0.01
c) Heifers
Full dataset¹	---	---	---
Abattoirs open all weeks²	1.61	1.35 – 1.94	<0.01
Multi-criteria³	1.70	1.42 – 2.04	<0.01
Large abattoirs⁴	2.86	2.38 – 3.43	<0.01
d) Steers
Full dataset¹	---	---	---
Abattoirs open all weeks²	1.39	1.20 – 1.61	<0.01
Multi-criteria³	1.48	1.28 – 1.72	<0.01
Large abattoirs⁴	2.02	1.74 – 2.34	<0.01

¹Abattoirs processing at least 1 bovine carcass each year of study period (2001 – 2007).
²Abattoirs processing at least 1 bovine carcass 52 weeks per year.
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).
⁴Abattoirs processing ≥ 6500 cattle per year.

ISSN: 1746-6148