BACKGROUND: Cannabis is increasingly available for the treatment of chronic pain, yet its efficacy remains uncertain.
PURPOSE: To review the benefits of plant-based cannabis preparations for treating chronic pain in adults and the harms of cannabis use in chronic pain and general adult populations.
DATA SOURCES: MEDLINE, Cochrane Database of Systematic Reviews, and several other sources from database inception to March 2017.
STUDY SELECTION: Intervention trials and observational studies, published in English, involving adults using plant-based cannabis preparations that reported pain, quality of life, or adverse effect outcomes.
DATA EXTRACTION: Two investigators independently abstracted study characteristics and assessed study quality, and the investigator group graded the overall strength of evidence using standard criteria.
DATA SYNTHESIS: From 27 chronic pain trials, there is low-strength evidence that cannabis alleviates neuropathic pain but insufficient evidence in other pain populations. According to 11 systematic reviews and 32 primary studies, harms in general population studies include increased risk for motor vehicle accidents, psychotic symptoms, and short-term cognitive impairment. Although adverse pulmonary effects were not seen in younger populations, evidence on most other long-term physical harms, in heavy or long-term cannabis users, or in older populations is insufficient.
LIMITATION: Few methodologically rigorous trials; the cannabis formulations studied may not reflect commercially available products; and limited applicability to older, chronically ill populations and patients who use cannabis heavily.
CONCLUSION: Limited evidence suggests that cannabis may alleviate neuropathic pain in some patients, but insufficient evidence exists for other types of chronic pain. Among general populations, limited evidence suggests that cannabis is associated with an increased risk for adverse mental health effects.
PRIMARY FUNDING SOURCE: U.S. Department of Veterans Affairs. (PROSPERO: CRD42016033623).
BACKGROUND: Cannabinoids have multiple medical indications in palliative care, such as relief of pain or nausea or increase of appetite and weight stabilisation. The value of cannabinoids for these indications is not resolved sufficiently for palliative patients. A systematic review with meta-analysis of the efficacy, tolerability and safety on the basis of randomised controlled studies (RCT) or randomised open label or crossover studies has not yet been conducted.
MATERIALS AND METHODS: An extensive search for RCTs, randomised open label or crossover studies dealing with the underlying question was performed in the databases of Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, PsycINFO, PubMed, Scopus and Clinicaltrials.gov up to April 2015. Studies with a duration of ≥ 2 weeks and ≥ 10 participants per treatment group were included into analysis. Using a random effects model, pooled estimates of event rates for categorical data and standardized mean differences (SMD) for continuous variables and risk differences (RD) for dichotomous variables were calculated.
RESULTS: Out of initially 108 studies 9, with a total of 1561 participants suffering from advanced or end stage diseases, were included. The median study duration of the cancer research was 8 weeks (16 days-11 weeks), of the HIV research 6 weeks (3-12 weeks) and of the study concentrating on Alzheimer's 2 × 6 weeks. The outcome results for cannabis/cannabinoids vs. placebo in patients with cancer were not significant for the 30 % decrease in pain (RD: 0.07; 95 % confidence interval (CI): - 0.01 to 0.16; p = 0.07), caloric intake (SMD 0.2; 95 % CI: - 0.66 to 1.06; p = 0.65) or sleep problems (SMD - 0.09; 95 % CI: - 0.62 to 0.43; p = 0.72). In the treatment of HIV cannabinoids were superior to placebo for the outcome of weight change (SMD 0.57; 95 % CI: 0.22-0.92; p = 0.001). Change in appetite was significant for the treatment of HIV (SMD 0.57; 95 % CI: 0.11-1.03; p = 0.02), but not for treatment of cancer (SMD 0.81; 95 % CI: - 1.14 to 2.75; p = 0.42). Nausea/vomiting (SMD 0.20; 95 % CI: - 0.03 to 0.44; p = 0.09) and health-related quality of life (HRQoL; SMD 0.00; 95 % CI: - 0.19 to 0.18; p = 0.98) did not show significant differences in the therapy of the two diseases. For the outcomes of tolerability the results were not significant for occurrence of dizziness (RD: 0.03; 95 % CI: - 0.02 to 0.08; p = 0.23) or psychiatric diseases, such as hallucinations or psychosis (RD: - 0.01; 95 % CI: - 0.04 to 0.03; p = 0.69) in the therapy of cancer. The outcome of psychiatric diseases in the treatment of HIV was significant (RD: 0.05; 95 % CI: 0.00-0.11; p = 0.05). The number of withdrawals due to adverse events, as a marker for tolerability, and the reports of serious adverse events as a measure of safety was not significantly different (RD: 1.20; 95 % CI: 0.85-1.71; p = 0.30 and RD: 1.15; 95 % CI: 0.88-1.49; p = 0.30, respectively). Dronabinol vs. megestrol acetate showed a superiority of megestrol in the therapy of cancer-associated anorexia for the endpoints change of appetite (49 vs. 75 %; p = 0.0001), weight gain (3 vs. 11 %; p = 0.02), HRQoL (p = 0.003) and tolerability (p = 0.03). There was no difference in the safety of the therapies (p = 0.12). In the treatment of HIV-associated wasting syndrome megestrol acetate was better than dronabinol for the endpoint of weight gain (p = 0.0001), whereas tolerability and safety did not differ. In the therapy of Alzheimer's dronabinol was better than placebo in the endpoint of weight gain according to one study (n = 15). A difference between herbal cannabis and synthetic cannabinoids, analysed by one study (n = 62) could not be found.
CONCLUSION: Cannabinoids can lead to an increase in appetite in patients with HIV wasting syndrome but the therapy with megestrol acetate is superior to treatment with cannabinoids. The included studies were not of sufficient duration to answer questions concerning the long-term efficacy, tolerability and safety of therapy with cannabis or cannabinoids. Due to the sparse amount of data it is not possible to recommend a favoured use of cannabis or cannabinoids at this point.
Pain intensity is frequently measured on an 11-point pain intensity numerical rating scale (PI-NRS), where 0 ¼ no pain and 10 ¼ worst possible pain. However, it is difficult to interpret the clinical importance of changes from baseline on this scale (such as a 1- or 2-point change). To date, there are no data driven estimates for clinically important differences in pain intensity scales used for chronic pain studies. We have estimated a clinically important difference on this scale by relating it to global assessments of change in multiple studies of chronic pain. Data on 2724 subjects from 10 recently completed placebo-controlled clinical trials of pregabalin in diabetic neuropathy, postherpetic neuralgia, chronic low back pain, fibromyalgia, and osteoarthritis were used. The studies had similar designs and measurement instruments, including the PI-NRS, collected in a daily diary, and the standard seven-point patient global impression of change (PGIC), collected at the endpoint. The changes in the PI-NRS from baseline to the endpoint were compared to the PGIC for each subject. Categories of ‘much improved’ and ‘very much improved’ were used as determinants of a clinically important difference and the relationship to the PI-NRS was explored using graphs, box plots, and sensitivity/specificity analyses. A consistent relationship between the change in PI-NRS and the PGIC was demonstrated regardless of study, disease type, age, sex, study result, or treatment group. On average, a reduction of approximately two points or a reduction of approximately 30% in the PI-NRS represented a clinically important difference. The relationship between percent change and the PGIC was also consistent regardless of baseline pain, while higher baseline scores required larger raw changes to represent a clinically important difference. The application of these results to future studies may provide a standard definition of clinically important improvement in clinical trials of chronic pain therapies. Use of a standard outcome across chronic pain studies would greatly enhance the comparability, validity, and clinical applicability of these studies. (PsycInfo Database Record (c) 2022 APA, all rights reserved)
Cannabis is increasingly available for the treatment of chronic pain, yet its efficacy remains uncertain.
PURPOSE:
To review the benefits of plant-based cannabis preparations for treating chronic pain in adults and the harms of cannabis use in chronic pain and general adult populations.
DATA SOURCES:
MEDLINE, Cochrane Database of Systematic Reviews, and several other sources from database inception to March 2017.
STUDY SELECTION:
Intervention trials and observational studies, published in English, involving adults using plant-based cannabis preparations that reported pain, quality of life, or adverse effect outcomes.
DATA EXTRACTION:
Two investigators independently abstracted study characteristics and assessed study quality, and the investigator group graded the overall strength of evidence using standard criteria.
DATA SYNTHESIS:
From 27 chronic pain trials, there is low-strength evidence that cannabis alleviates neuropathic pain but insufficient evidence in other pain populations. According to 11 systematic reviews and 32 primary studies, harms in general population studies include increased risk for motor vehicle accidents, psychotic symptoms, and short-term cognitive impairment. Although adverse pulmonary effects were not seen in younger populations, evidence on most other long-term physical harms, in heavy or long-term cannabis users, or in older populations is insufficient.
LIMITATION:
Few methodologically rigorous trials; the cannabis formulations studied may not reflect commercially available products; and limited applicability to older, chronically ill populations and patients who use cannabis heavily.
CONCLUSION:
Limited evidence suggests that cannabis may alleviate neuropathic pain in some patients, but insufficient evidence exists for other types of chronic pain. Among general populations, limited evidence suggests that cannabis is associated with an increased risk for adverse mental health effects.
