Estimating past hepatitis C infection risk from reported risk factor histories: implications for imputing age of infection and modeling fibrosis progression

Table 3 Multivariate models of HCV infection risk.

	Women's Interagency HIV Study			San Francisco Urban Health Study
Variable	Odds Ratio	95% CI	p	Odds Ratio	95% CI	p
Injection drug use (versus not injecting)
1st year of use	310	163 to 588	< 0.0001	61	21 to 177	< 0.0001
2^nd & 3^rd year	163	65 to 404	< 0.0001	9.8	1.94 to 50	0.0058
4^th or later year	7.2	2.1 to 24.2	0.0015	5.2	3.2 to 8.4	< 0.0001
Daily IDU (versus less frequent IDU)	1.14	0.73 to 1.77	0.57	1.59	1.40 to 1.81	< 0.0001
Male sex		(All Women)		0.76	0.67 to 0.85	< 0.0001
Age	See Figure 1a		< 0.0001		See Figure 1a	0.0001
Calendar Year	See Figure 1b		< 0.0001		See Figure 1b	< 0.0001
Race/ethnicity (versus Caucasian)
African American	1.50	1.05 to2.1	0.027	0.86	0.76 to 0.97	0.014
Hispanic	1.64	1.09 to 2.5	0.018	1.44	1.15 to 1.81	0.0018
Other	1.38	0.66 to 2.9	0.40	0.94	0.76 to 1.16	0.57
Area (versus San Francisco)
Bronx	1.41	0.96 to 2.1	0.080		(All San Francisco area)
Brooklyn	0.90	0.58 To 1.39	0.63
Washington DC	1.10	0.70 To 1.73	0.68
Los Angeles	0.80	0.51 to 1.26	0.33
Chicago	1.70	1.11 to 2.6	0.015
HIV infected	1.56	1.16 to 2.1	0.0030	1.27	1.09 to 1.47	0.0017

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