Table 2. Logistic regression of intensity of cannabis or cigarette use at age 16 and Depression at age 18 using imputed data (100 imputations), accounting for those with depression at age 16^* (N = 4561).

Model	Cannabis			Cigarettes
	OR	95% CI	P value	OR	95% CI	P value
1	1.50	1.26, 1.80	<0.001	1.37	1.16, 1.61	<0.001
2	1.52	1.26, 1.82	<0.001	1.29	1.09, 1.53	0.003
3	1.41	1.17, 1.71	<0.001	1.20	1.01, 1.43	0.033
4a	1.32	1.03, 1.68	0.027	1.11	0.90, 1.38	0.331
4b	1.35	1.09, 1.67	0.006	1.15	0.95, 1.40	0.155
4c	1.38	1.09, 1.75	0.007	1.15	0.95, 1.40	0.153
5	1.30	0.98, 1.72	0.065	1.09	0.87, 1.36	0.460

Model 1—Case depression at 18 by unit increase of 4-level categorical cumulative cannabis or frequency of cigarette use at 16.

Model 2—as model 1 with additional adjustment for pre birth confounders (family history of depression, gender, urban dwelling, maternal education).

Model 3—as model 2 with additional adjustment for childhood confounders (borderline personality, IQ at age 8, PEs at age 12, conduct disorder trajectory group membership, peer problems, bullied).

Model 4a —as model 3 with additional adjustment for cigarette use/cannabis use (as appropriate).

Model 4b —as model 3 with additional adjustment for alcohol use.

Model 4c —as model 3 with additional adjustment for illicit drug use (other than cannabis).

Model 5—as model 3 with additional adjustment for cigarette (or cannabis), alcohol, other illicit drug use.

* The imputed interaction model allowed us to account for 15% of participants who reported depression at age 16, without exclusions.