Risk differences for adverse events from comparative studies
| Outcome | Exposure | No of studies | No of participants | Follow-up (weeks) | Risk with cannabis (/1000) | Risk with comparator (/1000) | Risk difference (95% CI) | Certainty | Reasons for downgrading |
| All adverse events | Nabilone versus gabapentin | 1 | 220 | 24 | 404 | 534 | −13.1% (−26.2 to 0) | Very low | Risk of bias (two levels), imprecision |
| Adverse events causing discontinuation | Herbal cannabis versus standard care | 1 | 431 | 52 | 47 | 0 | 4.7% (1.8 to 7.5) | Low | Risk of bias (two levels), |
| Nabilone versus gabapentin | 1 | 220 | 24 | 96 | 190 | −9.4% (−18.5 to -0.2) | Very low | Risk of bias (two levels), imprecision | |
| Serious | Herbal cannabis versus standard care | 1 | 431 | 52 | 130 | 194 | 1.5% (−8.3 to 20.2)* | Low | Risk of bias, imprecision |
| Nabilone versus gabapentin | 1 | 220 | 24 | 0 | 0 | 0% (0 to 0) | Very low | Risk of bias (two levels), imprecision | |
| Psychiatric disorder | Herbal cannabis versus standard care | 1 | 431 | 52 | 219 | 97 | 16.9% (5.8 to 40.5)† | Very low | Risk of bias (two levels), imprecision |
| Suicide | Herbal cannabis versus standard care | 1 | 431 | 52 | 0 | 5 | −0.5% (−1.4 to 0.4) | Low | Risk of bias (two levels) |
| Mania | Herbal cannabis versus standard care | 1 | 431 | 52 | 5 | 0 | 0.5% (−0.4 to 1.4) | Low | Risk of bias (two levels) |
| Hallucinations | Herbal cannabis versus standard care | 1 | 431 | 52 | 5 | 0 | 0.5% (−0.4 to 1.4) | Low | Risk of bias (two levels) |
| Delusions | Herbal cannabis versus standard care | 1 | 431 | 52 | 0 | 5 | −0.5% (−1.4 to 0.4) | Low | Risk of bias (two levels) |
| Depression | Herbal cannabis versus standard care | 1 | 431 | 52 | 47 | 46 | 0.1% (−4 to 4) | Low | Risk of bias (two levels) |
| Paranoia | Herbal cannabis versus standard care | 1 | 431 | 52 | 9 | 0 | 0.9% (−0.4 to 2.2) | Low | Risk of bias (two levels) |
| Anxiety | Herbal cannabis versus standard care | 1 | 431 | 52 | 47 | 9 | 3.8% (0.6 to 6.8) | Low | Risk of bias (two levels) |
| Euphoria | Herbal cannabis versus standard care | 1 | 431 | 52 | 42 | 0 | 4.2% (1.5 to 6.9) | Low | Risk of bias (two levels) |
| Memory impairment | Herbal cannabis versus standard care | 1 | 431 | 52 | 19 | 0 | 1.9% (0.1 to 3.7) | Low | Risk of bias (two levels) |
| Confusion | Herbal cannabis versus standard care | 1 | 431 | 52 | 14 | 19 | −0.5% (−2.8 to 1.9) | Low | Risk of bias (two levels) |
| Disturbance in attention | Herbal cannabis versus standard care | 1 | 431 | 52 | 23 | 9 | 1.4% (−1 to 3.8) | Low | Risk of bias (two levels) |
| Falls | Herbal cannabis versus standard care | 1 | 431 | 52 | 23 | 23 | 0% (−2.8 to 2.9) | Low | Risk of bias (two levels) |
| Motor vehicle accidents | Herbal cannabis versus standard care | 1 | 431 | 52 | 5 | 0 | 0.5% (−0.4 to 1.4) | Low | Risk of bias (two levels) |
| Withdrawal syndrome | Herbal cannabis versus standard care | 1 | 431 | 52 | 5 | 0 | 0.5% (−0.4 to 1.4) | Very low | Risk of bias (two levels), |
*Risk difference calculated from adjusted incident rate ratio reported in study.
†Risk difference calculated from unadjusted incident rate ratio reported in study.