Table 2.

Developmental change in the association between substance use before sex and UAI with male partners

Main and moderating effects	Model 1			Model 2
	Event-rate ratio (ERR)	Confidence interval (95 %)	p value	Event-rate ratio (ERR)	Confidence interval (95 %)	p value
Alcohol use before sex	0.94	0.84–1.06	0.302	0.93	0.83–1.03	0.148
X age at each wave	–	–	–	1.06	1.00–1.13	<0.05
Drug use before sex	1.34	1.20–1.50	<0.001	1.44	1.32–1.58	<0.001
X age at each wave	–	–	–	0.93	0.88–0.99	<0.05

Main and moderating effects	Model 3			Model 4
	Event-rate ratio (ERR)	Confidence interval (95 %)	p value	Event-rate ratio (ERR)	Confidence interval (95 %)	p value
Alc. before sex X relationship type	1.00	0.82–1.22	0.990	0.91	0.71–1.16	0.445
X age at each wave	–	–	–	1.21	1.11–1.31	<0.001
Drug before sex X relationship type	0.82	0.69–0.98	<0.05	1.05	0.80–1.38	0.739
X age at each wave	–	–	–	0.93	0.85–1.03	0.158

Model 1 includes only the main effects of alcohol and drug use before sex on UAI. Model 2 includes the moderating effect of participant age on the relationship between substance use before sex and UAI. Model 3 includes the interaction between substance use before sex and relationship type in describing UAI. Model 4 includes the three-way interaction between participant age at each wave, relationship type, and substance use before sex in describing UAI. All models adjusted for key demographic covariates (age at wave, race, and self-reported sexual orientation). Models 2, 3, and 4 further adjusted for the main effects of all variables included in interaction terms. UAI unprotected anal intercourse