Table 2.

Multinomial logistic regressions of past-year use alcohol and/or cannabis use, adjusting for the interaction between sex and survey year (N= 37,799)

Covariate	Past-year simultaneous use (N=7,833) Vs. no use (N=11,586)	Past-year alcohol-use-only (N=13,509) Vs. no use	Past-year cannabis-use-only (N=608) Vs. no use	Past-year alcohol and cannabis use but not simultaneously (N=4,263) Vs. no use
	aRRR [95% CI]	aRRR [95% CI]	aRRR [95% CI]	aRRR [95% CI]
Survey year (ref=2000–2004)
2005–2009	0.78 [0.66, 0.93]	0.89 [0.76, 1.03]	0.96 [0.59, 1.57]	0.97 [0.80, 1.17]
2010–2014	0.79 [0.66, 0.94]	0.66 [0.58, 0.76]	1.53 [0.99, 2.36]	0.91 [0.76, 1.10]
2015–2020	0.50 [0.42, 0.60]	0.49 [0.43, 0.57]	2.30 [1.55, 3.40]	0.76 [0.62, 0.91]
Sex (ref=male)
Female	0.74 [0.64, 0.85]	1.05 [0.93, 1.19]	0.82 [0.51, 1.32]	1.07 [0.89, 1.28]
Sex × Survey year
Female × 2005–2009	1.10 [0.91, 1.34]	1.07 [0.91, 1.27]	1.13 [0.59, 2.15]	0.88 [0.69, 1.13]
Female × 2010–2014	0.97 [0.79, 1.19]	1.09 [0.92, 1.31]	0.83 [0.44, 1.55]	0.95 [0.74, 1.22]
Female × 2015–2020	1.31 [1.06, 1.61]	1.21 [1.01, 1.44]	1.26 [0.72, 2.21]	1.31 [1.03, 1.68]
Parental education (ref=finished college or more)
Some high school or lower	0.97 [0.83, 1.14]	0.94 [0.84, 1.05]	1.32 [0.93, 1.86]	1.08 [0.92, 1.26]
Finished high school or some college	1.16 [1.07, 1.25]	1.05 [0.98, 1.12]	1.37 [1.09, 1.70]	1.20 [1.10, 1.32]
Race/ethnicity (ref=white)
Black	0.41 [0.36, 0.47]	0.56 [0.50, 0.62]	2.41 [1.84, 3.17]	0.78 [0.68, 0.90]
Other	0.70 [0.64, 0.78]	0.85 [0.78, 0.92]	1.61 [1.27, 2.04]	0.95 [0.85, 1.05]
Survey mode (ref=paper)
Tablet	0.93 [0.73, 1.19]	0.86 [0.70, 1.06]	1.19 [0.81, 1.74]	0.92 [0.75, 1.13]

Note: aRRR=Adjusted relative risk ratio. Alcohol-use-only is defined as past-year alcohol use and no report of past-year cannabis or simultaneous use. Cannabis-use-only is defined as past-year cannabis use and no report of past-year alcohol or simultaneous use. Models also adjusted for parental education, race/ethnicity, and survey mode.