Table 3.

Associations between age at first substance use and cannabis use frequency among subjects who reported using cannabis in the last month – linear regression (n = 394)

Age at first use	Cannabis use frequency
	β	S.E.	95% CI	P-value
All subjects
Alcohol (n = 386)
Model 1	−0.807	0.25	−1.295, −0.318	.001
Model 2	−0.781	0.25	−1.269, −0.294	.002
Model 3	−0.452	0.24	−0.928, 0.023	.062
Tobacco (n = 368)
Model 1	−0.653	0.15	−0.946, −0.360	<.001
Model 2	−0.674	0.15	−0.968, −0.379	<.001
Model 3	−0.547	0.15	−0.836, −0.258	<.001
Cannabis (n = 390)
Model 1	−0.675	0.12	−0.918, −0.432	<.001
Model 2	−0.793	0.13	−1.042, −0.543	<.001
Model 3	−0.634	0.12	−0.878, −0.390	<.001
Subjects aged 15–34 years
Alcohol (n = 298)
Model 1	−0.962	0.29	−1.531, −0.393	.001
Model 2	−0.982	0.29	−1.552, −0.412	.001
Model 3	−0.661	0.29	−1.228, −0.093	.023
Tobacco (n = 282)
Model 1	−1.430	0.20	−1.829, −1.032	<.001
Model 2	−1.458	0.21	−1.862, −1.054	<.001
Model 3	−1.138	0.21	−1.560, −0.717	<.001
Cannabis (n = 302)
Model 1	−1.413	0.20	−1.801, −1.026	<.001
Model 2	−1.521	0.20	−1.912, −1.130	<.001
Model 3	−1.343	0.21	−1.751, −0.935	<.001

Unstandardized β coefficients, standard errors (S.E.) and 95% confidence intervals (CI) are shown

Model 1: univariate

Model 2: adjusted for sex and age (continuous)

Model 3: adjusted for sex, age, marital status, region, education, employment, housing tenure, other lifetime drug use, current use of alcohol or tobacco and year of data collection