Factors associated with whole carcass condemnation rates in provincially-inspected abattoirs in Ontario 2001-2007: implications for food animal syndromic surveillance

Table 6 Multivariable negative binomial model using a GEE¹ approach

Covariate	IRR²	Robust Standard Error	P-value	95% CI
Animal class
Calves	---	---	---	---
Cows	6.73	2.40	< 0.001	3.35 - 13.52
Heifers	0.47	0.10	< 0.001	0.31 - 0.72
Steers	0.46	0.12	0.01	0.29 - 0.74
Year
2001	---	---	---	---
2002	1.37	0.21	0.04	1.02 - 1.84
2003	0.70	0.16	0.11	0.45 - 1.09
2004	0.56	0.13	0.02	0.36 - 0.90
2005	0.93	0.20	0.74	0.61 - 1.43
2006	1.05	0.23	0.80	0.69 - 1.63
2007	1.16	0.29	0.56	0.71 - 1.88
Season
Winter	---	---	---	---
Spring	0.88	0.07	0.07	0.76 - 1.01
Summer	0.82	0.06	0.01	0.71 - 0.95
Fall	0.77	0.05	< 0.001	0.69 - 0.87
Audit rating
C	---	---	---	---
AAA	0.32	0.30	0.22	0.05 - 2.01
AA	0.43	0.12	0.01	0.25 - 0.74
A	0.64	0.11	0.01	0.46 - 0.89
B	0.56	0.11	0.01	0.39 - 0.82
unrated	1.41	0.35	0.17	0.87 - 2.31
Price
Below median	---	---	---	---
Above median	1.12	0.05	0.02	1.02 - 1.23
Year x animal class
Calves and 2001	---	---	---	---
Cows and 2002	0.61	0.12	0.01	0.42 - 0.88
Cows and 2003	1.13	0.34	0.69	0.63 - 2.05
Cows and 2004	0.83	0.30	0.61	0.40 - 1.72
Cows and 2005	0.48	0.14	0.01	0.27 - 0.86
Cows and 2006	0.45	0.12	0.01	0.27 - 0.78
Cows and 2007	0.51	0.19	0.06	0.25 - 1.04
Heifers and 2002	0.61	0.14	0.03	0.39 - 0.95
Heifers and 2003	1.46	0.44	0.21	0.81 - 2.65
Heifers and 2004	1.05	0.30	0.85	0.61 - 1.83
Heifers and 2005	0.88	0.24	0.63	0.51 - 1.50
Heifers and 2006	0.93	0.22	0.77	0.59 - 1.48
Heifers and 2007	0.71	0.23	0.29	0.39 - 1.33
Steers and 2002	0.74	0.14	0.12	0.51 - 1.08
Steers and 2003	1.40	0.43	0.28	0.77 - 2.54
Steers and 2004	1.63	0.50	0.11	0.89 - 2.99
Steers and 2005	1.02	0.28	0.94	0.60 - 1.73
Steers and 2006	1.42	0.44	0.26	0.78 - 2.61
Steers and 2007	0.90	0.32	0.77	0.45 - 1.81
Correlation value = 0.067

¹ Generalized estimating equation using an exchangeable correlation structure to account for repeated measurements among provincial abattoirs
² Incidence rate ratio
Multivariable negative binomial models using a GEE¹ approach investigating the association between condemnation rates in Ontario provincial abattoirs and animal class, year, season, price, year-animal class interaction and audit rating based on the multivariable GEE model.

ISSN: 1746-6148