Table 2.

Negative binomial models that include the effect of season, year, and the interaction between season and year on the rate of different condemnation codes from a federally inspected abattoir in southern Ontario from 2005–2007

	Total condemned			Arthritis			Pneumonia			Enteritis			Nephritis
	IRRa	95% CI b	P-value	IRR	95% CI	P-value	IRR	95% CI	P-value	IRRa	95% CI b	P-value	IRR	95% CI	P-value
Seasonc
Spring	0.93	0.83–1.04	0.22	1.39	1.06–1.82	0.02	0.84	0.58–1.22	0.35	1.01	0.53–1.93	0.97	2.23	1.50–3.33	< 0.001
Summer	1.01	0.90–1.13	0.83	1.33	1.02–1.73	0.03	1.03	0.72–1.46	0.85	1.10	0.60–2.04	0.74	1.73	1.16–2.60	0.007
Fall	1.05	0.94–1.17	0.37	1.13	0.86–1.49	0.34	0.68	0.47–0.98	0.04	0.71	0.36–1.41	0.33	2.88	1.97–4.21	< 0.001
Yeard
2006	1.01	0.90–1.12	0.88	1.30	1.00–1.69	0.05	1.04	0.73–0.47	0.81	1.02	0.55–1.91	0.93	2.65	1.81–3.88	< 0.001
2007	0.89	0.80–0.99	0.05	1.09	0.84–1.43	0.49	0.61	0.42–0.89	0.01	7.29	4.41–12.06	< 0.001	5.48	3.82–7.84	< 0.001
Interactions
Spring 2006	0.62	0.53–0.73	< 0.001	0.50	0.34–0.74	< 0.001	0.44	0.25–0.76	0.003	1.99	0.86–4.63	0.10	0.38	0.23–0.64	< 0.001
Spring 2007	0.86	0.73–1.01	0.06	0.70	0.48–1.01	0.06	1.27	0.75–2.16	0.36	0.51	0.25–1.07	0.07	0.45	0.29–0.72	0.001
Summer 2006	0.46	0.39–0.55	< 0.001	0.32	0.22–0.48	< 0.001	0.26	0.15–0.46	< 0.001	2.59	1.17–5.74	0.02	0.62	0.38–1.02	0.06
Summer 2007	0.39	0.39–0.46	< 0.001	0.36	0.24–0.54	< 0.001	0.29	0.16–0.53	< 0.001	0.28	0.14–0.58	0.001	0.26	0.16–0.43	< 0.001
Fall 2006	0.67	0.57–0.78	< 0.001	0.55	0.37–0.79	0.002	0.65	0.39–1.11	0.11	5.21	2.26–12.02	< 0.001	0.46	0.29–0.74	0.001
Fall 2007	0.46	0.39–0.53	< 0.001	0.21	0.13–0.32	< 0.001	0.29	0.15–0.55	< 0.001	0.14	0.67–0.34	< 0.001	0.13	0.87–0.20	< 0.001

^aIncidence rate ratio.

^bConfidence intervals.

^cReferent winter.

^dReferent 2005.