Table 5.

Impact of interviewer identity on associations between baseline covariates and HIV testing history in ZEST trial

	Month 1 follow-up, tested in past 30 days						Month 4 follow-up, tested in past 30 days
1. No covariates
Study arm A	1.00		1.00		1.00		1.00		1.00		1.00
Study arm B	1.07	[1.02–1.12]	1.07	[0.94–1.21]	1.07	[0.95–1.20]	1.11	[1.03–1.21]	1.13	[0.98–1.31]	1.14	[0.98–1.31]
Study arm C	0.95	[0.89–1.01]	0.95	[0.84–1.07]	0.94	[0.85–1.05]	1.06	[0.97–1.15]	1.07	[0.95–1.21]	1.08	[0.96–1.22]
Female vs. male interviewer					0.97	[0.91–1.04]					1.39	[0.70–2.73]
Interviewer random effects			Yes		Yes				Yes		Yes
2. Age
18–24	1.00		1.00		1.00		1.00		1.00		1.00
25–29	0.96	[0.92–1.02]	0.96	[0.91–1.03]	0.96	[0.91–1.03]	1.00	[0.93–1.08]	1.01	[0.93–1.10]	1.01	[0.93–1.10]
30–34	0.94	[0.88–1.01]	0.94	[0.87–1.02]	0.94	[0.87–1.02]	0.99	[0.91–1.08]	0.97	[0.91–1.04]	0.97	[0.91–1.04]
35+	0.94	[0.87–1.01]	0.94	[0.85–1.03]	0.94	[0.85–1.03]	0.92	[0.81–1.05]	0.91	[0.80–1.03]	0.91	[0.80–1.03]
Female vs. male interviewer					0.97	[0.91–1.04]					1.39	[0.70–2.74]
Interviewer random effects			Yes		Yes				Yes		Yes
3. Sexual abuse
Any sexual abuse as adult	1.01	[0.97–1.06]	1.01	[0.97–1.06]	1.01	[0.97–1.06]	0.92	[0.86–0.98]	0.98	[0.90–1.05]	0.97	[0.90–1.05]
Female vs. male interviewer					0.97	[0.91–1.04]					1.38	[0.70–2.72]
Interviewer random effects			Yes		Yes				Yes		Yes

This table summarizes results from 18 regressions (nine for each outcome). Full regression output is provided in Additional file 1: Table S2

All regressions are generalized linear models with a Poisson distribution and log link, and robust standard errors. All contain fixed effects for study arm (even when not shown here) and site. Month 1 N = 884; month 4 N = 892