Table 3. Multivariable model results from multinomial logistic model of markers of recent infection^a and logistic regression model of combined outcome, among people who inject drugs, England, Wales and Northern Ireland, 2011–13 (n = 2,816).

Variable	Category	Logistic model		Multinomial logistic model
		Combined OR (95% CI)	p value	RNA RRR (95% CI)	p value	Avidity RRR (95% CI)	p value	p value diffb
Gender	Male	1 (ref)	0.022	1 (ref)	0.152	1 (ref)	0.072	0.962
	Female	1.59 (1.07–2.37)		1.55 (0.85–2.84)		1.61 (0.97–2.68)
Regional prevalence	Low (<40%)	1.08 (0.69–1.71)	0.237	1.73 (0.83–3.57)	0.339	0.77 (0.42–1.38)	0.086	0.104
	Medium (40–55%)	1 (ref)		1 (ref)		1 (ref)
	High (>55%)	1.41 (0.91–2.18)		1.45 (0.68–3.06)		1.40 (0.83–2.37)
Injecting durationc	<1 year	1.00 (0.46–2.16)	0.790	1.01 (0.28–3.68)	0.309	0.99 (0.38–2.53)	0.129	0.032
	1–5 years	0.85 (0.52–1.38)		1.53 (0.75–3.12)		0.49 (0.25–0.96)
	6–10 years	1 (ref)		1 (ref)		1 (ref)
	11–14 years	0.74 (0.42–1.29)		0.68 (0.26–1.75)		0.77 (0.39–1.51)
	15–19 years	0.77 (0.43–1.38)		0.78 (0.30–2.02)		0.77 (0.38–1.57)
	≥20 years	1.09 (0.61–1.93)		0.61 (0.19–1.92)		1.34 (0.69–2.61)
Homelessness	Never	1 (ref)	0.237	1 (ref)	0.631	1 (ref)	0.103	0.234
	Yes, not past year	1.49 (0.89–2.48)		1.38 (0.66–2.91)		1.61 (0.81–3.20)
	Yes, past year	1.52 (0.92–2.51)		1.11 (0.52–2.36)		1.90 (0.97–3.71)
Imprisonment	Never	1 (ref)	0.003	1 (ref)	0.122	1 (ref)	0.019	0.974
	1–4 times	0.76 (0.48–1.20)		0.80 (0.40–1.61)		0.74 (0.41–1.35)
	≥5 times	1.62 (1.06–2.48)		1.63 (0.83–3.17)		1.65 (0.96–2.81)
Crack injecting	No	1 (ref)	< 0.001	1 (ref)	0.009	1 (ref)	< 0.001	0.949
	Yes	2.32 (1.58–3.41)		2.28 (1.22–4.24)		2.32 (1.45–3.72)
Injecting and sharing past month	Did not inject past month	1 (ref)	< 0.001	1 (ref)	0.036	1 (ref)	< 0.001	0.438
	Injected and did not share	1.20 (0.68–2.10)		0.86 (0.39–1.89)		1.61 (0.73–3.59)
	Injected and shared	2.69 (1.52–4.73)		1.83 (0.83–4.06)		3.79 (1.69–8.50)

CI: 95% confidence interval; OR: odds ratio; ref: reference value; RRR: relative risk ratio.

^a RNA-positive antibody-negative (RNA marker) and antibody-positive with weak avidity (avidity marker).

^b p value diff is the p value for the effect estimates for RNA and avidity being the same.

^c Using three duration categories 0–5, 6–14 and ≥15 years, with 6–14 years as baseline, the pattern is similar. For the 0–5 years category for RNA, RRR = 1.64 (95% CI: 0.91–2.98) and for avidity, RRR = 0.80 (95% CI: 0.38–1.70). For the ≥15 years category for the RNA, RRR = 0.62 (95% CI: 0.36–1.07) and for avidity, RRR = 1.07 (95% CI: 0.66–1.73).