Shiga toxin-producing escherichia coli infections in Norway, 1992–2012: characterization of isolates and identification of risk factors for haemolytic uremic syndrome

Table 3 Risk factors for HUS among 333 STEC patients, Norway, 1992–2012

Determinant^a	No. of patients		Predictive values^b		Univariable analyses^c	Multivariable analyses^{c, d}
	All (333)	HUS (25)	PPV	NPV	OR (95 % CI)	Model 1 (risk factors)	Model 2 (preventive factors)	Model 3 (all factors)
	All (333)	HUS (25)	PPV	NPV	OR (95 % CI)	OR (95 % CI)	OR (95 % CI)	OR (95 % CI)
Age ≤ 5 yr	130	22	16.9 %	98.5 %	13.6 (4.0-46.4)	12.2 (3.2-46.7)		16.7 (4.24-65.7)
Bloody diarrhea	119	13	10.9 %	99.4 %	19.5 (2.5-151.3	ND^e
Diarrhea	148	1	0.7 %	78.1 %	0.1 (0.008-0.5)		ND
Hospitalized^f	141	24	17.0 %	100.0 %	ND
SF O157	9	5	55.6 %	93.8 %	19.0 (4.7-76.3)	NS^g
O145	24	5	20.8 %	93.5 %	3.8 (1.3-11.2)
O145:H?	6	4	66.7 %	93.6 %	29.1 (5.0-168.4)	NS
stx1	215	1^h	0.5 %	79.7 %	0.02 (0.002-0.1)		0.02 (0.002-0.1)	0.1 (0.01-0.8)
stx1a	189	1^h	0.5 %	83.3 %	0.03 (0.004-0.2)
stx2	207	25	12.1 %	100.0 %	ND
stx2a	85	24	28.2 %	99.6 %	97.2 (12.9-732.5)	92.7 (10.7-803.5)		30.1 (3.3-271.9)
stx2c	100	2	2.0 %	90.1 %	0.2 (0.04-0.8		0.2 (0.03-0.7)	0.6 (0.1-3.3)
eae	245	25	10.2 %	100.0 %	ND

^aAll determinants associated with HUS (p ≤ 0.05) were included
^bPPV; positive predictive value, NPV; negative predictive value
^cOR; odds ratio, CI; 95 % confidence interval
^dModel 1; factors related to increased risk of developing HUS, Model 2; factors related to reduced risk of HUS, and Model 3; comprising both factors related to increased and decreased risk of HUS
^eND; not determined since all HUS cases were hospitalized and all HUS isolates carried stx2 and eae
^fInformation on hospitalization was not available for 37 patients, including one HUS patient
^gNS; not statistically significant
^hOne HUS patients had two STEC isolates; one with stx1a + stx2a and another with stx1a only

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