Page 8 - Cannabis for the Management of Pain: Assessment of Safety Study

1240 The Journal of Pain Cannabis for the Management of Pain
Table 4. Unadjusted and Adjusted Rate Ratios of AEs for Medical Cannabis
CANNABIS CONTROL UNADJUSTED IRR (95% CI) ADJUSTED IRR* (95% CI)
All patients
Number of patients 215 216 – –
Cumulative person-years 176.9 204.1 – –
Number of SAEs 40 56 .82 (.46–1.46) 1.08 (.57–2.04)
Number of AEs 818 574 1.64 (1.35–1.99) 1.74 (1.42–2.14)
Patients excluding ‘‘current cannabis users’’y at baseline
Number of patients 74 216 – –
Cumulative person-years 52.2 204.1 – –
Number of SAEs 20 56 1.40 (.66–2.93) 1.77 (.72–4.32)
Number of AEs 316 574 2.15 (1.69–2.74) 2.07 (1.59–2.70)
*Adjusted for age at enrollment, gender, baseline pain intensity, baseline concomitant pain medication (yes/no), disability status (yes/no), tobacco use (current vs former
or never smokers), alcohol use (current vs former or never users), past cannabis use (ever/never), and study sites.
y‘‘Current cannabis users’’ were those who reported using cannabis and were still using at the baseline interview.

Pain and Other Symptoms with an increased risk of non-serious AEs, particularly
with respect to nervous system and psychiatric disorders.
The sensory component of pain was reduced over 1 year
in cannabis users compared with controls (Supplementary This adverse event profile is similar to pharmaceutical
16
cannabinoids.
Tables 19 and 20). The total symptom distress score of the
We found 78 respiratory events in the cannabis group
Edmonton Symptom Assessment Scale was also improved
and 56 in the control group, and most were considered
in cannabis users over 1 year (Supplementary Tables 21
mild or moderate. No increase in risk of serious respira-
and 22). The total mood disturbance scale of the Profile
tory AEs associated with medical cannabis use was
of Mood States showed significant improvement for
detected (1 SAE in the cannabis group, and 7 in the con-
cannabis users compared with controls, with
trol group). Medical cannabis users had a higher rate of
improvements found in the tension-anxiety, depression-
developing non-serious respiratory AEs during 1 year of
dejection, anger-hostility, and fatigue-inertia subscales
(Supplementary Tables 23 and 24). follow-up compared with controls. This is consistent
with reports that long-term cannabis smoking is associ-
ated with an increased risk of chronic bronchitis. 12 In
Discussion our study, cannabis users had a mean 50-mL decrease in
To our knowledge, this is the first cohort study of the FEV 1 and a mean 1% decrease in the FEV 1 /FVC ratio
long-term safety of medical cannabis use ever conduct- over 1 year.
ed. Over 1 year, we identified 40 SAEs among 28 patients, Neurocognitive function improved in both groups.
and 818 non-serious AEs among 190 patients using med- This finding differs from that found in recreational
ical cannabis. Headache, nasopharyngitis, nausea, som- users of cannabis; a meta-analysis of 15 studies investi-
nolence, and dizziness were the most common AEs gating the effects of recreational cannabis use on neu-
reported. Medical cannabis use did not increase the risk rocognitive performance 6 suggested that long-term
of SAEs compared with controls but was associated cannabis users performed significantly poorer on tests

Table 5. Neurocognitive Measures in Cannabis-Exposed and Control Individuals Over 1 Year*
GROUP NUMBER OF PATIENTS BASELINE 6MONTHS 12 MONTHS
WMS-III y
Verbal paired associates I
Recall (max 32 points) Cannabis 77 16.92 (7.69) 20.97 (8.01) 22.97 (7.56)
Control 53 17.42 (7.85) 19.25 (8.70) 22.72 (8.53)
Verbal paired associates II
Recall (max 8 points) Cannabis 76 5.67 (2.35) 6.29 (2.05) 6.54 (1.81)
Control 53 5.45 (2.55) 6.02 (2.45) 6.64 (1.95)
Recognition (max 24 points) Cannabis 76 23.80 (.80) 23.92 (.32) 23.78 (1.41)
Control 53 23.94 (.23) 23.98 (.14) 23.98 (.14)
WAIS-III z
Digit symbol-coding (max 133 points) Cannabis 72 52.21 (21.60) 53.31 (23.64) 55.90 (23.11)
Control 53 49.94 (18.82) 54.64 (20.26) 55.00 (17.65)
Picture arrangement (max 22 points) Cannabis 76 11.64 (3.91) 13.67 (5.03) 14.18 (4.36)
Control 53 11.42 (4.65) 13.32 (5.14) 14.24 (5.53)

*Data are presented as mean (SD).
yWMS-III, Wechsler Memory Scale, Third Edition.
zWAIS-III: Wechsler Adult Intelligence Scale, Third Edition.