Table 3.
Multinomial multivariable logistic regression predicting substance use group membership
| Alcohol/tobacco vs. no substance use | Cannabis vs. no substance use | ATS vs. no substance use | ||||
|---|---|---|---|---|---|---|
| RRRAdj (95% CI) | p value | RRRAdj (95% CI) | p value | RRRAdj (95% CI) | p value | |
| Age in years | 1.36 (1.27–1.46) | < 0.001 | 1.33 (1.23–1.44) | < 0.001 | 1.58 (1.42–1.77) | < 0.001 |
| Sex at birth | ||||||
| Female | Ref | Ref | Ref | |||
| Male | 0.67 (0.46–0.98) | 0.037 | 1.00 (0.66–1.51) | 0.996 | 0.87 (0.48–1.57) | 0.651 |
| LGBTIQA+ | ||||||
| No | Ref | Ref | Ref | |||
| Yes | 1.05 (0.70–1.58) | 0.806 | 1.66 (1.06–2.59) | 0.027 | 0.92 (0.48–1.78) | 0.807 |
| Region | ||||||
| Metro | Ref | Ref | Ref | |||
| Regional | 1.96 (1.35–2.83) | < 0.001 | 1.95 (1.30–2.92) | 0.001 | 3.13 (1.79–5.48) | < 0.001 |
| Education and employment status | ||||||
| Studying only | Ref | Ref | Ref | |||
| Working only | 4.03 (1.99–8.15) | < 0.001 | 3.46 (1.64–7.33) | 0.001 | 8.41 (3.18–22.22) | < 0.001 |
| Studying and working | 3.02 (1.95–4.67) | < 0.001 | 2.01 (1.22–3.32) | 0.007 | 3.56 (1.57–8.04) | 0.002 |
| Not studying or working | 1.39 (0.77–2.50) | 0.272 | 1.98 (1.08–3.64) | 0.028 | 3.08 (1.25–7.59) | 0.015 |
| Primary diagnosis | ||||||
| Depression | Ref | Ref | Ref | |||
| Anxiety | 0.66 (0.39–1.13) | 0.129 | 0.80 (0.42–1.52) | 0.492 | 0.94 (0.38–2.32) | 0.901 |
| Depression and Anxiety | 0.88 (0.52–1.48) | 0.633 | 1.44 (0.78–2.63) | 0.241 | 0.97 (0.41–2.27) | 0.942 |
| Other | 0.71 (0.40–1.23) | 0.221 | 1.36 (0.71–2.60) | 0.348 | 2.09 (0.88–4.99) | 0.097 |
| PHQ-9 | 0.87 (0.65–1.17) | 0.358 | 0.88 (0.63–1.22) | 0.444 | 1.09 (0.69–1.73) | 0.708 |
| GAD-7 | 0.86 (0.66–1.11) | 0.235 | 0.86 (0.65–1.15) | 0.323 | 0.81 (0.53–1.23) | 0.314 |
| RRS-10 | 1.06 (0.84–1.34) | 0.607 | 1.06 (0.82–1.36) | 0.656 | 1.40 (0.97–2.01) | 0.071 |
| PSQI | 1.28 (1.02–1.59) | 0.032 | 1.05 (0.82–1.34) | 0.705 | 1.10 (0.77–1.57) | 0.594 |
| CAS | 1.08 (0.86–1.35) | 0.514 | 1.37 (1.08–1.74) | 0.009 | 1.09 (0.79–1.51) | 0.582 |
| PQ-16 | 1.23 (1.00–1.52) | 0.049 | 1.12 (0.89–1.41) | 0.334 | 1.25 (0.90–1.73) | 0.177 |
RRRAdj: relative risk ratio estimated using multivariate multinomial logistic regression with missing data imputed via MICE. Participants were grouped according to ATS use (may use other substances), cannabis use without ATS (may use other substances), primarily alcohol and/or tobacco (use substances other than cannabis or ATS) and no substance use, and PHQ-9 (The Patient Health Questionnaire), GAD-7 (Generalised Anxiety Disorder), RRS-10 (Rumination Response Scale), PSQI (Pittsburgh Sleep Quality Index), CAS (Clinical Anger Scale) and PQ-16 (Prodromal Questionnaire) total scores were standardised for ease of comparison