Table 4.

Multivariate analysis of the effect of participation in harm reduction programmes on HIV and HCV seroconversion.

	HIV			HCV
	IRR	95% CI	P-value	IRR	95% CI	P-value
Level of harm reduction (definitions described in Table 1)
No harm reduction	1		< 0.001	1		< 0.001
Incomplete harm reduction	0.87	0.50–1.52		1.17	0.59–2.31
Full harm reduction	0.43	0.21–0.87		0.36	0.13–1.03
Limited dependence on harm reduction	0.046	0.006–0.35		0.044	0.006–0.35
No dependence on harm reduction	0.20	0.078–0.50		0.13	0.044–0.40
Time since start injection drug use (per year)	0.95	0.92–0.98	< 0.001	0.87	0.81–0.93	< 0.001
HIV status of steady partner
No steady partner	1		0.004	1		0.026
HIV-positive steady partner	4.53	2.23–9.21		3.49	0.84–14.5
HIV-negative steady partner	0.82	0.43–1.57		0.42	0.13–1.37
Steady partner with unknown HIV status	0.75	0.18–3.06

IRR = incidence rate ratio, 95% CI = 95% confidence interval.