Table 4.

Results of multivariable logistic regression of Salmonella risk categorisation on pig farms (n = 250)

Variable	Category	Higher risk	Lower risk	% Higher risk	Odds ratio	95% Confidence interval		P-value
						Lower	Upper
No. of sows	0	18	47	27.7	1.000
	<400	4	81	4.7	0.099	0.026	0.371	0.001
	401–1000	7	30	18.9	0.686	0.184	2.558	0.574
	1000+	4	19	17.4	1.407	0.278	7.124	0.680
	Not known	8	32	20.0	0.539	0.165	1.757	0.305
Are rodent baits used in the surroundings of the farm enclosures?	No	18	45	28.6	1.000
	Yes	22	147	13.0	0.265	0.105	0.668	0.005
	NA	1	17	5.6	0.151	0.013	1.778	0.133
Are stay-behinds always isolated from the healthy ones (in physically separated hospital area / or by euthanasia)?	No	19	55	25.7	1.000
	Yes	21	147	12.5	0.280	0.112	0.700	0.006
	N/A	1	6	14.3	0.338	0.030	3.815	0.381
Is the floor in each anteroom / hygiene lock even / without damages and thereby easy to clean and to disinfect?	Yes	37	164	18.4	1.000
	No	4	45	8.2	0.156	0.040	0.601	0.007
Are all farm buildings/ fields surrounded by a perimeter fence?	Single or double fenced	31	123	20.1	1.000
	No	9	64	12.3	0.191	0.062	0.589	0.004
	Partly interrupted	1	22	4.3	0.093	0.010	0.853	0.036
Which standard cleaning and disinfection procedures are used in the farrowing barns between batches? – Downtime (at least 3 days)	No	34	130	20.7	1.000
	Yes	7	79	8.1	0.252	0.079	0.803	0.020
What kind of flooring system is in the barn sections for fatteners?	Any other flooring	23	66	25.8	1.000
	Only solid floor	3	29	9.4	0.209	0.042	1.047	0.057
	Only full slats	9	69	11.5	0.293	0.103	0.833	0.021
	Not present/missing	6	45	11.8	0.352	0.102	1.214	0.098