Table 2:
Bivariate and multivariate analyses of risk factors for incident methamphetamine use
| Incident methamphetamine use (cases/person-years) |
Crude methamphetamine incidence (95% CI) |
Bivariate analysis hazard ratio (95% CI) |
Multivariate analysis hazard ratio (95% CI) |
|
|---|---|---|---|---|
| Total | 128/3371 | 3·8 (3·2–4·5) | ·· | ·· |
| Age (years) | ||||
| 18–21 | 31/492 | 6·3 (4·3–8·9) | 3·0 (1·7–5·1) | 2·0 (1·2–3·6) |
| 22–29 | 75/1811 | 4·1 (3·3–5·2) | 2·0 (1·2–3·2) | 1·6 (1·0–2·6) |
| ≥30 | 22/1069 | 2·1 (1·3–3·1) | 1 (ref) | 1 (ref) |
| Education | ||||
| Primary | 3/44 | 6·8 (1·4–19·9) | 2·8 (0·9–8·9) | ·· |
| Secondary or vocational | 80/1499 | 5·3 (4·2–6·6) | 2·2 (1·5–3·1) | ·· |
| University and above | 45/1828 | 2·8 (1·8–3·3) | 1 (ref) | ·· |
| Study or work status | ||||
| Work | 61/2031 | 3·0 (2·3–3·9) | 1 (ref) | ·· |
| Work and study | 56/1218 | 4·6 (3·5–6·0) | 1·5 (1·1–2·2) | ·· |
| Neither | 11/122 | 9·0 (4·5–16·1) | 3·1 (1·6–5·9) | ·· |
| Current living situation | ||||
| With family | 44/1416 | 3·1 (2·3–4·2) | 1 (ref) | ·· |
| With partner | 13/471 | 2·8 (1·5–4·7) | 0·9 (0·5–1·6) | ·· |
| Alone or with housemate | 71/1486 | 4·8 (3·7–6·0) | 1·5 (1·0–2·2) | ·· |
| Used erectile dysfunction drugs in past 4 months | ||||
| Yes | 61/194 | 31·5 (24·1–40·4) | 16·5 (11·6–23·4) | ·· |
| No | 67/3177 | 2·1 (1·6–2·7) | 1 (ref) | ·· |
| Anal sex in past 4 months | ||||
| Yes | 126/3099 | 4·1 (3·4–4·8) | 5·2 (1·3–20·9) | ·· |
| No | 2/272 | 0·8 (0·1–26·6) | 1 (ref) | ·· |
| Total number of male partners | ||||
| None | 2/242 | 0·8 (0·1–3·0) | 1 (ref) | ·· |
| 1–5 | 54/2307 | 2·3 (1·8–3·0) | 2·7 (0·6–11·0) | ·· |
| ≥6 | 72/823 | 8·7 (6·9–11·0) | 9·7 (2·4–39·7) | ·· |
| Condom use with male partner in past 4 months* | ||||
| Always | 60/1955 | 3·1 (2·3–4·0) | 1 (ref) | ·· |
| Not always | 66/1144 | 5·8 (4·5–7·3) | 1·8 (1·3–2·6) | ·· |
| Ever had group sex | ||||
| Yes | 56/465 | 12·0 (9·1–15·6) | 4·8 (3·4–6·9) | ·· |
| No | 72/2906 | 2·5 (1·9–3·1) | 1 (ref) | ·· |
| Ever coerced into sex | ||||
| Yes | 27/529 | 5·1 (3·4–7·4) | 1·47 (1·0–2·2) | ·· |
| No | 101/2839 | 3·6 (2·9–4·3) | 1 (ref) | ·· |
| Ever received money for sex | ||||
| Yes | 27/226 | 12·0 (7·9–17·4) | 3·4 (2·2–5·3) | 2·3 (1·4–3·6) |
| No | 101/3146 | 3·2 (2·6–3·9) | 1 (ref) | 1 (ref) |
| Finding casual sex partners on the internet in past 4 months | ||||
| Yes | 69/988 | 7·0 (5·4–8·8) | 2·8 (2·0–4·0) | 2·1 (1·4–3·0) |
| No | 59/2383 | 2·5 (1·9–3·2) | 1 (ref) | 1 (ref) |
| Attended chemsex party in past 4 months* | ||||
| Yes | 22/53 | 41·7 (26·1–63·2) | 14·9 (9·3–24·0) | 10·0 (6·2–16·4) |
| No | 85/3060 | 2·78 (2·2–3·4) | 1 (ref) | 1 (ref) |
Only significant variables are reported for the multivariate analysis.
*
Missing values for this factor were handled by an indicator variable.