Table 8.

Odds ratio, 95% CI,^a and P‐value for a priori risk factors of respiratory morbidity and mortality

Risk Factor	Outcome
	Mortality at Any Time During the Feeding Period	P Value	Diagnosis of Feverb on Arrival	P Value	Diagnosis of Feverb After Arrival, at Any Time in Feeding Period	P Value	Diagnosis of Feverb After Arrival, Within 10 days After Sample Collection	P Value
M. haemolytica status of arrival sample
Negative	Reference		Reference		Reference		Reference
Positive	1.1 (0.3–2.9)	.93	1.4 (0.7–1.7)	.38	1.2 (1.0–1.6)	.24	1.7 (1.1–2.4)	.07
Risk status of cattle
Low risk	Reference	.03	Reference	.008	Reference	<.001	Reference	<.001
Medium risk	3.5 (0.4–90.2)		2.9 (2.1–7.0)		1.7 (1.7–3.2)		2.1 (1.5–4.0)
High risk	13.7 (2.2–285.7)		2.7 (1.4–4.3)		5.6 (4.1–7.8)		2.5 (1.5–4.1)
Very high risk	3.8 (0.4–111.7)		0.5 (0.2–0.9)		2.7 (1.8–3.8)		0.3 (0.1–0.6)
Arrival season of cattle
Winter (Jan–Mar)	Reference	.21	Reference	.09	Reference	.002	Reference	.002
Spring (Apr–Jun)	0.3 (0.01–2.7)		5.2 (2.2–11.4)		1.3 (0.6–1.7)		1.2 (0.5–2.5)
Summer (Jul–Sept)	0.3 (0.03–2.0)		2.3 (0.9–4.7)		2.5 (1.4–3.0)		1.2 (0.5–1.0)
Fall (Oct–Dec)	1.3 (0.3–5.2)		2.7 (1.1–5.2)		3.9 (2.5–5.1)		3.1 (1.6–5.1)
Pen size
<101	Reference	.23	Reference	.38	Reference	.24	Reference	.97
101–200	3.1 (0.54–56.6)		1.2 (0.6–2.7)		1.7 (1.2–2.8)		1.0 (0.5–2.0)
201–300	1.6 (0.1–37.0)		0.4 (0.1–1.5)		1.6 (1.0–2.8)		1.0 (0.5–2.4)
301–400	0.4 (0.02–15.4)		1.8 (0.9–6.1)		1.6 (1.0–2.9)		0.8 (0.4–2.2)
>400	1.6 (0.2–92.6)		0.6 (0.3–2.5)		2.8 (1.6–5.2)		0.9 (0.3–2.7)

^a95% CI represent likelihood ratio‐based CI.

^bSystemic illness with fever (bovine respiratory disease).