Table 2.
Effects of Pattern of Cannabis Use on the Hazard for Experiencing Onset of Psychotic Disorder at Any Given Time
| Mean (SD); Median (y) Age of Onset of Psychosis | Adjusted Hazard Ratioa | 95% CI | P Value | |
|---|---|---|---|---|
| Cannabis use | ||||
| Never | 31.4 (9.9); 30.0 | — | ||
| Yes | 28.2 (8.0); 27.1 | 1.39 | 1.11–1.68 | <.001 |
| Type used independent of frequency of use | ||||
| Hash-like (low potency) | 30.1 (9.6); 28.9 | — | ||
| Skunk-like (high potency) | 26.7 (6.3) 25.2 | 1.68 | 1.08–2.63 | .002 |
| Frequency of use independent of type used | ||||
| Less than daily | 29.8 (9.2); 28.5 | — | ||
| Daily | 27.1 (7.8); 25.9 | 1.60 | 1.11–2.31 | .011 |
| Age at first use of cannabis | ||||
| >15 y | 29.1 (8.5); 27.8 | — | ||
| ≤15 y | 27.0 (6.2); 26.9 | 1.36 | 1.04–1.80 | .050 |
| Age at first use of cannabis independent of type used and frequency of use | ||||
| >15 y | 29.1 (8.5); 27.8 | — | ||
| ≤15 y | 28.9 (8.2); 27.4 | 1.18 | 0.81–1.73 | .37 |
| Hazard ratio for the effect of degree of exposure to cannabis | ||||
| Never used cannabis | 31.4 (9.9); 30.0 | — | ||
| Hash less than weekly | 31.1 (9.5); 29.8 | 0.90 | 0.49–1.28 | .357 |
| Hash everyday | 29.5 (8.9); 27.4 | 1.15 | 0.64–2.09 | .624 |
| Skunk less than weekly | 26.5 (7.6); 25.3 | 1.48 | 1.17–2.04 | .015 |
| Skunk everyday | 25.2 (6.3); 24.6 | 1.99 | 1.50–2.65 | <.0001 |
Note: aAll the above HR adjusted for gender.