Table 2.

Results of multivariable analysis–STEC O157 PT21/28

Variable	Detail	All (n = 839)			Excluding foreign travel (n = 815)			Excluding all travel (n = 620)
		IRR	95% CI	P	IRR	95% CI	P	IRR	95% CI	P
Cattle density (animals/km2)	0–17	1	–	<0.001	1	–	<0.001	1	–	0.002
	18–44	1.42	1.17–1.73		1.43	1.17–1.74		1.34	1.07–1.69
	45–86	1.36	1.04–1.77		1.35	1.03–1.77		1.25	0.91–1.71
	87–199	1.98	1.46–2.68		2.01	1.48–2.73		1.93	1.36–2.76
Sheep density (animals/km2)	0–36	1	–	<0.001	1	–	<0.001	1	–	<0.001
	37–104	1.19	0.97–1.46		1.21	0.98–1.50		1.27	1.00–1.62
	105–216	1.83	1.42–2.38		1.85	1.43–2.41		2.04	1.50–2.77
	217–572	2.48	1.77–3.46		2.49	1.78–3.50		2.75	1.85–4.09
Pig density (animals/km2)	0–19	1	–	0.029	1	–	0.021	1	–	0.034
	20–63	1.10	0.90–1.34		1.12	0.92–1.37		1.02	0.80–1.30
	64–169	1.38	1.01–1.88		1.39	1.02–1.90		1.60	1.13–2.25
	170–499	2.02	1.11–3.69		2.09	1.15–3.83		1.71	0.79–3.73
Number of PWS	0	1	–	0.002	1	–	0.002	1	–	0.056
	1–20	1.35	1.07–1.70		1.34	1.06–1.69		1.10	0.83–1.46
	>20	1.94	1.33–2.82		1.94	1.32–2.84		1.70	1.09–2.64
Residence	Urban: major conurbation	1	–	0.212	1	–	0.193	1	–	0.018
	Urban: minor conurbation	1.23	0.83–1.83		1.23	0.82–1.84		1.34	0.87–2.05
	Urban: city and town	1.00	0.83–1.21		1.00	0.83–1.22		0.92	0.74–1.15
	Rural: town and fringe	1.09	0.83–1.44		1.11	0.84–1.47		1.09	0.79–1.51
	Rural: village	1.35	0.99–1.83		1.37	1.01–1.87		1.52	1.07–2.18
IMD	1 (most deprived)	1	–	0.256	1	–	0.167	1	–	0.002
	2	0.91	0.73–1.14		0.89	0.70–1.11		0.75	0.58–0.96
	3	0.79	0.62–0.99		0.76	0.60–0.97		0.65	0.50–0.84
	4	0.80	0.63–1.01		0.77	0.61–0.98		0.60	0.46–0.78
	5 (least deprived)	0.85	0.68–1.08		0.83	0.66–1.06		0.67	0.51–0.87

IRR, incidence rate ratio; IMD, index of multiple deprivation; CI, confidence interval