Table 5.
Adjusted odds ratios with 95% confidence intervals for developing schizophrenia any time after conscription for subjects taking cannabis only
| Drug use | No of subjects | No (%) of subjects developing schizophrenia | Odds ratio (95% CI)
|
|
|---|---|---|---|---|
| Crude
|
Adjusted*
|
|||
| Cannabis ever† | 1635 | 18 (1.1) | 1.9 (1.2 to 3.0) | 1.9 (1.1 to 3.1) |
| Frequency of use of cannabis (ever): | ||||
| None | 36 429 | 215 (0.6) | 1.0† | 1.0† |
| Once | 245 | 0 | — | — |
| 2-4 times | 499 | 5 (1.0) | 1.7 (0.7 to 4.2) | 1.9 (0.8 to 4.8) |
| 5-10 times | 255 | 3 (1.2) | 2.0 (0.6 to 6.3) | 1.7 (0.5 to 5.7) |
| 11-50 times | 176 | 1 (0.6) | 1.0 (0.1 to 6.9) | 0.8 (0.1 to 6.0) |
| >50 times | 70 | 4 (5.7) | 10.2 (3.7 to 28.3) | 6.7 (2.1 to 21.7) |
| Linear trend for frequency of use | — | — | 1.3 (1.1 to 1.6) | 1.3 (1.0 to 1.5) |
*
Adjusted for diagnosis at conscription, IQ score, poor social integration, disturbed behaviour, cigarette smoking, and place of upbringing.
†
No drug use as baseline comparison.