Marijuana and lung diseases

Cannabis Science and Therapeutics: An Overview for Clinicians

Cannabis-based therapeutics have garnered increasing attention in recent years as patients seek alternative treatments for various medical conditions. This narrative review provides a comprehensive overview of the science behind the medical use of cannabis, focusing on the medical evidence for commonly treated conditions. In addition, the review addresses the practical considerations of using cannabis as a therapeutic agent, offering insights into dosing strategies, variations in cannabinoid formulation, and individual patient responses. Precautions, adverse consequences, and drug interactions are also discussed, with a focus on patient safety and the potential risks associated with cannabis use.

Cardiovascular and Respiratory Effects of Cannabis Use by Route of Administration: A Systematic Review

Aim: Knowledge of the cardiovascular and respiratory effects of cannabis use by route of administration is unclear. This evidence is necessary to increase clinical and public health awareness given the recent trend in cannabis legalization, normalization, and surge in the availability and usage of various forms of cannabis products. Methods: Search was conducted in Web of Science, ProQuest, Psych INFO, Scopus, Embase, and Medline databases, and subsequently in the references of retrieved articles. Peer-reviewed articles published between 2009 and 2023, that reported on cardiovascular and respiratory effects of cannabis use by route of administration were included. Studies with no report of the route of administration and combined use of other illicit substances were excluded. The review was guided by Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Results: Of the 1873 articles retrieved, 42 met inclusion criteria encompassing six case reports, 21 reviews, and 15 empirical studies. Four administration routes were identified: smoking, vaping, oral ingestion, and dabbing. Smoking was the most common route of administration and was associated with both respiratory effects, such as bronchitis, dyspnea, and chronic obstructive lung disease, and cardiovascular effects including tachycardia, ventricular arrhythmias, and myocardial infarction. Cannabis edibles were associated with minimal respiratory effects. Tachycardia was the most common cardiovascular effect and was associated with all routes of administration. Conclusion: Cannabis use does cause cardiovascular and respiratory effects, but the conclusion remains tentative of the cardiovascular and respiratory effects by route of administration due to methodological limitations of the studies.

Vanishing Lung Syndrome in a Young Male With Chronic Marijuana Use: A Case Report

Vanishing lung syndrome (VLS) also known as type I bullae disease or idiopathic bullous disease is characterized by giant emphysematous bullae that commonly develop in the upper lobes, occupying at least one-third of a hemithorax. It is a progressive and irreversible condition that involves pulmonary parenchymal destruction and alveolar dilation. It is commonly associated with middle-aged tobacco smokers, habitual marijuana users, and those with alpha-1-antitrypsin deficiency. This case involves an incarcerated male in his 30s with chronic marijuana smoking who presented with a three-month history of right-sided chest pain accompanied by cough, hemoptysis, fever, and weight loss. The patient reported month-long atypical chest discomfort associated with a cough productive of bloody sputum and was brought to the ED after developing acutely worsening right-sided chest pain. The patient underwent a chest X-ray that revealed a large pneumothorax on the left. Subsequently, CT chest imaging showed extensive bilateral bullous disease, left upper lobe consolidation, and enlarged mediastinal lymph nodes. This case illustrates a rare presentation of VLS in the setting of a young patient who other than reported regular marijuana use had no other risk factors and a negative workup for possible etiologies that could cause his severe bullous emphysema, including alpha-1 antitrypsin, HIV, Sjogren's syndrome, pulmonary Langerhans cell histiocytosis, two sputum Mycobacterium tuberculosis tests, and acid-fast bacteria sputum cultures, which were all negative. Identifying and assessing the degree of disease early in this progressive disease helps guide treatment while preventing further deterioration of lung parenchyma.

Differential inflammatory profile in the lungs of mice exposed to cannabis smoke with varying THC:CBD ratio

Cannabis contains cannabinoids including Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD). THC causes the psychoactive effects of cannabis, and both THC and CBD are thought to be anti-inflammatory. Cannabis is typically consumed by inhaling smoke that contains thousands of combustion products that may damage the lungs. However, the relationship between cannabis smoke exposure and alterations in respiratory health is poorly defined. To address this gap in knowledge, we first developed a mouse model of cannabis smoke exposure using a nose-only rodent inhalation exposure system. We then tested the acute effects of two dried cannabis products that differ substantially in their THC-CBD ratio: Indica-THC dominant (I-THC; 16-22% THC) and Sativa-CBD dominant (S-CBD; 13-19% CBD). We demonstrate that this smoke exposure regime not only delivers physiologically relevant levels of THC to the bloodstream, but that acute inhalation of cannabis smoke modulates the pulmonary immune response. Cannabis smoke decreased the percentage of lung alveolar macrophages but increased lung interstitial macrophages (IMs). There was also a decrease in lung dendritic cells as well as Ly6Cintermediate and Ly6Clow monocytes, but an increase in lung neutrophils and CD8+ T cells. These immune cell changes were paralleled with changes in several immune mediators. These immunological modifications were more pronounced when mice were exposed to S-CBD compared to the I-THC variety. Thus, we show that acute cannabis smoke differentially affects lung immunity based on the THC:CBD ratio, thereby providing a foundation to further explore the effect of chronic cannabis smoke exposures on pulmonary health.

Modulation of pulmonary immune function by inhaled cannabis products and consequences for lung disease

The lungs, in addition to participating in gas exchange, represent the first line of defense against inhaled pathogens and respiratory toxicants. Cells lining the airways and alveoli include epithelial cells and alveolar macrophages, the latter being resident innate immune cells important in surfactant recycling, protection against bacterial invasion and modulation of lung immune homeostasis. Environmental exposure to toxicants found in cigarette smoke, air pollution and cannabis can alter the number and function of immune cells in the lungs. Cannabis (marijuana) is a plant-derived product that is typically inhaled in the form of smoke from a joint. However, alternative delivery methods such as vaping, which heats the plant without combustion, are becoming more common. Cannabis use has increased in recent years, coinciding with more countries legalizing cannabis for both recreational and medicinal purposes. Cannabis may have numerous health benefits owing to the presence of cannabinoids that dampen immune function and therefore tame inflammation that is associated with chronic diseases such as arthritis. The health effects that could come with cannabis use remain poorly understood, particularly inhaled cannabis products that may directly impact the pulmonary immune system. Herein, we first describe the bioactive phytochemicals present in cannabis, with an emphasis on cannabinoids and their ability to interact with the endocannabinoid system. We also review the current state-of-knowledge as to how inhaled cannabis/cannabinoids can shape immune response in the lungs and discuss the potential consequences of altered pulmonary immunity. Overall, more research is needed to understand how cannabis inhalation shapes the pulmonary immune response to balance physiological and beneficial responses with potential deleterious consequences on the lungs.

Place of therapeutic cannabis in France and safety data: A literature review

OBJECTIVES

To date, very few cannabis-based specialities are authorised on the French market despite a growing demand from patients and health professionals. The objective of this study is to review the tolerance profile and the French legislative status of the two main cannabinoids used for therapeutic purposes: tetrahydrocannabiol (THC) associated with psychoactive effects and non-psychoactive cannabidiol (CBD).

METHODS

This review is based on relevant articles retrieved by a search in Google Scholar and PubMed databases and on an assessment of the legal texts and summaries of product characteristics available in France.

RESULTS

Evidence for the tolerability of CBD during chronic use is reassuring, but a significant risk of drug interactions exists. THC use appears to be associated with a higher proportion of serious adverse effects, including neuropsychological and cardiovascular effects. Inhaled cannabis appears to be associated with greater toxicity than the oral route. These data are presented together with the pharmacokinetic and pharmacodynamic data of THC and CBD.

CONCLUSION

The literature reports several frequent but rarely serious adverse effects of CBD during chronic use as well as a significant risk of drug interactions. THC use seems to be associated with a higher proportion of serious adverse effects compared to CBD, particularly at the neuropsychological and cardiovascular levels. Health professionals should be up to date on the particularities of therapeutic cannabis in terms of efficacy, safety and drug interactions.

Use of Electronic Cigarettes and Other Tobacco Products Among Active Component Services Members

INTRODUCTION

e-cigarettes have been touted as a safer alternative to classic cigarettes and other combustible tobacco products. However, a growing body of evidence finds that any risk reduction associated with e-cigarette use is eliminated when individuals use "both" e-cigarettes and other tobacco products. Recent analyses from the Health Related Behaviors Survey suggest that rates of e-cigarette use are higher among active component service members than in the general population. However, little is known about the frequency and health behaviors associated with the dual use of e-cigarettes and other tobacco products among service members.

DATA AND METHOD

Using data from the 2018 Health Related Behaviors Survey, this paper investigates whether active component service members who use both e-cigarettes and other tobacco products are more likely to engage in other types of substance use or negative health behaviors.

RESULTS

We find that the dual use of e-cigarettes and other tobacco products is associated with poorer physical and mental health, higher rates of alcohol misuse, and higher rates of insufficient sleep.

CONCLUSION

The association between the dual use of e-cigarettes and tobacco products suggests that these individuals represent an important target group for health-related resources and attention in DoD.

Efficacy of cannabis-based medications compared to placebo for the treatment of chronic neuropathic pain: a systematic review with meta-analysis

Background

Chronic neuropathic pain (NP) presents therapeutic challenges. Interest in the use of cannabis-based medications has outpaced the knowledge of its efficacy and safety in treating NP. The objective of this review was to evaluate the effectiveness of cannabis-based medications in individuals with chronic NP.

Methods

Randomized placebo-controlled trials using tetrahydrocannabinol (THC), cannabidiol (CBD), cannabidivarin (CBDV), or synthetic cannabinoids for NP treatment were included. The MEDLINE, Cochrane Library, EMBASE, and Web of Science databases were examined. The primary outcome was the NP intensity. The risk of bias analysis was based on the Cochrane handbook.

Results

The search of databases up to 2/1/2021 yielded 379 records with 17 RCTs included (861 patients with NP). Meta-analysis showed that there was a significant reduction in pain intensity for THC/CBD by -6.624 units (P < .001), THC by -8.681 units (P < .001), and dronabinol by -6.0 units (P = .008) compared to placebo on a 0-100 scale. CBD, CBDV, and CT-3 showed no significant differences. Patients taking THC/CBD were 1.756 times more likely to achieve a 30% reduction in pain (P = .008) and 1.422 times more likely to achieve a 50% reduction (P = .37) than placebo. Patients receiving THC had a 21% higher improvement in pain intensity (P = .005) and were 1.855 times more likely to achieve a 30% reduction in pain than placebo (P < .001).

Conclusion

Although THC and THC/CBD interventions provided a significant improvement in pain intensity and were more likely to provide a 30% reduction in pain, the evidence was of moderate-to-low quality. Further research is needed for CBD, dronabinol, CT-3, and CBDV.

Wonder or evil?: Multifaceted health hazards and health benefits of Cannabis sativa and its phytochemicals

Cannabis sativa, widely known as 'Marijuana' poses a dilemma for being a blend of both good and bad medicinal effects. The historical use of Cannabis for both medicinal and recreational purposes suggests it to be a friendly plant. However, whether the misuse of Cannabis and the cannabinoids derived from it can hamper normal body physiology is a focus of ongoing research. On the one hand, there is enough evidence to suggest that misuse of marijuana can cause deleterious effects on various organs like the lungs, immune system, cardiovascular system, etc. and also influence fertility and cause teratogenic effects. However, on the other hand, marijuana has been found to offer a magical cure for anorexia, chronic pain, muscle spasticity, nausea, and disturbed sleep. Indeed, most recently, the United Nations has given its verdict in favour of Cannabis declaring it as a non-dangerous narcotic. This review provides insights into the various health effects of Cannabis and its specialized metabolites and indicates how wise steps can be taken to promote good use and prevent misuse of the metabolites derived from this plant.

Pharmacological properties, therapeutic potential, and legal status of Cannabis sativa L.: An overview

Marijuana, or Cannabis sativa L., is a common psychoactive plant used for both recreational and medicinal purposes. In many countries, cannabis-based medicines have been legalized under certain conditions because of their immense prospects in medicinal applications. With a comprehensive insight into the prospects and challenges associated with the pharmacological use and global trade of C. sativa, this mini-review focuses on the medicinal importance of the plant and its legal status worldwide; the pharmacological compounds and its therapeutic potential along with the underlying public health concerns and future perspective are herein discussed. The existence of major compounds including Δ⁹ -tetrahydrocannabinol (Δ⁹ -THC), cannabidiol, cannabinol, and cannabichromene contributes to the medicinal effects of the cannabis plant. These compounds are also involved in the treatment of various types of cancer, epilepsy, and Parkinson's disease displaying several mechanisms of action. Cannabis sativa is a plant with significant pharmacological potential. However, several aspects of the plant need an in-depth understanding of the drug mechanism and its interaction with other drugs. Only after addressing these health concerns, legalization of cannabis could be utilized to its full potential as a future medicine.

Development and validation of an open-source, disposable, 3D-printed in vitro environmental exposure system for Transwell culture inserts

Accessible in vitro models recapitulating the human airway that are amenable to study whole cannabis smoke exposure are needed for immunological and toxicological studies that inform public health policy and recreational cannabis use. In the present study, we developed and validated a novel three-dimensional (3D)-printed in vitro exposure system (IVES) that can be directly applied to study the effect of cannabis smoke exposure on primary human bronchial epithelial cells.

Using commercially available design software and a 3D printer, we designed a four-chamber Transwell insert holder for exposures to whole smoke. COMSOL Multiphysics software was used to model gas distribution, concentration gradients, velocity profile and shear stress within IVES. Following simulations, primary human bronchial epithelial cells cultured at the air–liquid interface on Transwell inserts were exposed to whole cannabis smoke using a modified version of the Foltin puff procedure. Following 24 h, outcome measurements included cell morphology, epithelial barrier function, lactate dehydrogenase (LDH) levels, cytokine expression and gene expression.

Whole smoke delivered through IVES possesses velocity profiles consistent with uniform gas distribution across the four chambers and complete mixing. Airflow velocity ranged between 1.0 and 1.5 µm·s⁻¹ and generated low shear stresses (<<1 Pa). Human airway epithelial cells exposed to cannabis smoke using IVES showed changes in cell morphology and disruption of barrier function without significant cytotoxicity. Cannabis smoke elevated interleukin-1 family cytokines and elevated CYP1A1 and CYP1B1 expression relative to control, validating IVES smoke exposure impacts in human airway epithelial cells at a molecular level.

The growing legalisation of cannabis on a global scale must be paired with research related to potential health impacts of lung exposures. IVES represents an accessible, open-source, exposure system that can be used to model varying types of cannabis smoke exposures with human airway epithelial cells grown under air–liquid interface culture conditions.

Development of an open-source, disposable, 3D-printed in vitro environmental exposure system for Transwell culture inserts that can be used for environmental exposures important for lung health, and validation with cannabis smoke exposurehttps://bit.ly/2JjgDrm

Cannabinoids and Opioids in the Treatment of Inflammatory Bowel Diseases

In traditional medicine, Cannabis sativa has been prescribed for a variety of diseases. Today, the plant is largely known for its recreational purpose, but it may find a way back to what it was originally known for: a herbal remedy. Most of the plant's ingredients, such as Δ-tetrahydrocannabinol, cannabidiol, cannabigerol, and others, have demonstrated beneficial effects in preclinical models of intestinal inflammation. Endogenous cannabinoids (endocannabinoids) have shown a regulatory role in inflammation and mucosal permeability of the gastrointestinal tract where they likely interact with the gut microbiome. Anecdotal reports suggest that in humans, Cannabis exerts antinociceptive, anti-inflammatory, and antidiarrheal properties. Despite these reports, strong evidence on beneficial effects of Cannabis in human gastrointestinal diseases is lacking. Clinical trials with Cannabis in patients suffering from inflammatory bowel disease (IBD) have shown improvement in quality of life but failed to provide evidence for a reduction of inflammation markers. Within the endogenous opioid system, mu opioid receptors may be involved in anti-inflammation of the gut. Opioids are frequently used to treat abdominal pain in IBD; however, heavy opioid use in IBD is associated with opioid dependency and higher mortality. This review highlights latest advances in the potential treatment of IBD using Cannabis/cannabinoids or opioids.

Mandatory pharmacist-led education session for patients seeking medical cannabis

Objective:

The primary objectives of this pre-post session study, was to evaluate the impact of a pharmacist-led education session on the perceived benefits and safety of cannabis among patients with chronic pain, as well as determine the influence of pharmacist education on the selection of safer cannabis products and dosage forms for medical use among patients.

Methods:

A retrospective analysis of completed pre-post session questionnaires was conducted among chronic pain patients attending a mandatory education session led by a pharmacist, prior to being authorized cannabis in clinic. All questionnaire data was analyzed using SPSS v. 25. Demographic and sample characteristics were reviewed using univariate analyses. Chi-Square tests were employed to determine if the group-based education significantly affected knowledge, perception of efficacy and safety of cannabis.

Results:

Of the 260 session participants, 203 completed pre-post session questionnaires. After the session, a majority of current cannabis users (33.8%) and cannabis naïve/past users (56.9%) reported they would use a low THC product in the future, and a majority of current users (54.5%) would use a high CBD product in the future. After education, participants were more likely to report cannabis as having the potential for addiction (chi-square =42.6, p <0.0001) and harm (chi-square =34.0, p <0.0001).

Conclusions:

Pharmacist counselling and education has the potential to influence patient selection and use of cannabis, from more harmful to safer products, as well as moderate the potential perceived benefits of use.

An overview of cannabis based treatment in Crohn's disease

Introduction: Cannabis use among inflammatory bowel disease (IBD) patients is common. There are many studies of various laboratory models demonstrating the anti-inflammatory effect of cannabis, but their translation to human disease is still lacking.Areas covered: The cannabis plant contains many cannabinoids, that activate the endocannabinoid system. The two most abundant phytocannabinoids are the psychoactive Tetrahydrocannabinol (THC), and the (mostly) anti-inflammatory cannabidiol (CBD). Approximately 15% of IBD patients use cannabis to ameliorate disease symptoms. Unfortunately, so far there are only three small placebo controlled study regarding the use of cannabis in active Crohns disease, combining altogether 93 subjects. Two of the studies showed significant clinical improvement but no improvement in markers of inflammation.Expert opinion: Cannabis seems to have a therapeutic potential in IBD. This potential must not be neglected; however, cannabis research is still at a very early stage. The complexity of the plant and the diversity of different cannabis chemovars create an inherent difficulty in cannabis research. We need more studies investigating the effect of the various cannabis compounds. These effects can then be investigated in randomized placebo controlled clinical trials to fully explore the potential of cannabis treatment in IBD.

A health promotion intervention to improve lifestyle choices and health outcomes in people with psychosis: a research programme including the IMPaCT RCT

Background

People with psychotic disorders have reduced life expectancy largely because of physical health problems, especially cardiovascular disease, that are complicated by the use of tobacco and cannabis.

Objectives

We set out to (1) chart lifestyle and substance use choices and the emergence of cardiometabolic risk from the earliest presentation with psychosis, (2) develop a pragmatic health promotion intervention integrated within the clinical teams to improve the lifestyle choices and health outcomes of people with psychosis and (3) evaluate the clinical effectiveness and cost-effectiveness of that health promotion intervention.

Design

We performed a longitudinal cohort study of people presenting with their first episode of psychosis in three mental health trusts and followed up participants for 1 year [work package 1, physical health and substance use measures in first episode of psychosis (PUMP)]. We used an iterative Delphi methodology to develop and refine a modular health promotion intervention, improving physical health and reducing substance use in psychosis (IMPaCT) therapy, which was to be delivered by the patient’s usual care co-ordinator and used motivational interviewing techniques and cognitive–behavioural therapy to improve health choices of people with psychosis (work package 2). We then conducted a multicentre, two-arm, parallel-cluster, randomised controlled trial to determine the clinical effectiveness and cost-effectiveness of using the intervention with people with established psychosis (work package 3: IMPaCT randomised controlled trial) in five UK mental health trusts. The work took place between 2008 and 2014.

Participants

All people aged between 16 and 65 years within 6 months of their first presentation with a non-organic psychosis and who were proficient in English were eligible for inclusion in the PUMP study. Participants in the work package 2 training development were staff selected from a range of settings, working with psychosis. Participants in the phase 3 Delphi consensus and manual development comprised three expert groups of (1) therapists/researchers recruited from the local and national community, (2) clinicians and (3) service users, each of whom took part in two iterative review and feedback sessions. For work package 3, IMPaCT randomised controlled trial, care co-ordinators in participating community mental health teams who were permanently employed and had a minimum of four eligible patients (i.e. aged between 18 and 65 years with a diagnosis of a psychotic disorder) on their caseload were eligible to participate. In studies 1 and 3, patient participants were ineligible if they were pregnant or had a major illness that would have had an impact on their metabolic status or if they had a significant learning disability. All participants were included in the study only after giving written confirmed consent.

Main outcome measures

Cardiometabolic risk markers, including rates of obesity and central obesity, and levels of glycated haemoglobin (HbA1c) and lipids, were the main outcomes in work package 1 (PUMP), with descriptive data presented on substance use. Our primary outcome measure for the IMPaCT randomised controlled trial was the physical or mental health component Short Form questionnaire-36 items quality-of-life scores at 12 months.

Results

Obesity rates rose from 18% at first presentation with psychosis to 24% by 1 year, but cardiometabolic risk was not associated with baseline lifestyle and substance use choices. Patterns of increase in the levels of HbA1c over the year following first presentation showed variation by ethnic group. We recruited 104 care co-ordinators, of whom 52 (with 213 patients) were randomised to deliver IMPaCT therapy and 52 (with 193 patients) were randomised to deliver treatment as usual, in keeping with our power calculations. Of these 406 participants with established psychosis, 318 (78%) and 301 (74%) participants, respectively, attended the 12- and 15-month follow-ups. We found no significant effect of IMPaCT therapy compared with treatment as usual on the physical or mental health component Short Form questionnaire-36 items scores at either time point in an intention-to-treat analysis [physical health score (‘d’) –0.17 at 12 months and –0.09 at 15 months; mental health score (‘d’) 0.03 at 12 months and –0.05 at 15 months] or on costs. Nor did we find an effect on other cardiovascular risk indicators, including diabetes, except in the case of high-density lipoprotein cholesterol, which showed a trend for greater benefit with IMPaCT therapy than with treatment as usual (treatment effect 0.085, 95% confidence interval 0.007 to 0.16; p = 0.034).

Limitations

Follow-up in work package 1 was challenging, with 127 out of 293 participants attending; however, there was no difference in cardiometabolic measures or demographic factors at baseline between those who attended for follow-up and those who did not. In work package 3, the IMPaCT randomised controlled trial, care co-ordinators struggled to provide additional time to their patients that was devoted to the health promotion intervention on top of their usual clinical care contact with them.

Conclusions

Cardiometabolic risk is prominent even soon after first presentation with psychosis and increases over time. Lifestyle choices and substance use habits at first presentation do not predict those who will be most cardiometabolically compromised 1 year later. Training and supervising care co-ordinators to deliver a health promotion intervention to their own patients on top of routine care is not effective in the NHS for improving quality of life or reducing cardiometabolic risk.

Future work

Further work is needed to develop and evaluate effective, cost-effective and affordable ways of preventing the emergence of and reversing existing cardiometabolic risk indicators in people with psychosis.

Trial registration

Current Controlled Trials ISRCTN58667926.

Funding

This project was funded by the National Institute for Health Research (NIHR) Programme Grants for Applied Research programme and will be published in full in Programme Grants for Applied Research; Vol. 8, No. 1. See the NIHR Journals Library website for further project information.

Cannabis Use Disorder and Post-Deployment Suicide Attempts in Iraq/Afghanistan-Era Veterans

The objective of the present study was to use retrospective data to test the hypothesis that cannabis dependence would be associated with an increased rate of post-deployment suicide attempts. Participants included 319 veterans who had deployed to either Iraq or Afghanistan. Study procedures involved completion of a structured clinical interview and a battery of self-report questionnaires. As expected, lifetime cannabis dependence was significantly associated with post-deployment suicide attempts, AOR = 7.963, p = .014, even after controlling for the effects of pre-deployment suicide attempts, posttraumatic stress disorder, depression, pain, non-cannabis substance use disorder, and gender. Although preliminary, our findings provide the first evidence to date that heavy cannabis use may be a unique risk factor for post-deployment suicide attempts among veterans.

Cannabis use and the risk of tuberculosis: a systematic review

BACKGROUND

Cannabis has been identified as a possible risk factor in some tuberculosis (TB) outbreaks. As the most widely used (largely) illegal substance in Western countries this may be an important public health concern. We aim to systematically review the evidence on the association between cannabis use and TB (latent infection and active disease) to inform ongoing and future TB prevention and control strategies.

METHODS

We conducted a systematic review. We searched Ovid Medline, Embase and PsycInfo, together with the World Health Organization website and Google Scholar, for all years to January 2018. Reference lists and conference abstracts were hand-searched, a forward citation search was conducted on the Web of Science, and experts were contacted. Two authors independently screened studies for inclusion, extracted data and assessed risk of bias using an adapted version of ROBINS-I ("Risk of Bias in Non-randomised Studies - of Interventions"). Data were narratively synthesised.

RESULTS

Of 377 records identified, 11 studies were eligible. Study designs were heterogeneous. Six studies utilised a relevant comparator group. Four of these investigated the association between cannabis use and latent TB infection; all provided some evidence of an association, although only two of these had adjusted for confounders. The remaining two comparator studies investigated the association between cannabis use and active TB disease; neither found evidence of an association after adjusting for confounding. All six studies were at "Serious" risk of bias. The five studies which did not utilise a relevant comparator group were all indicative of TB outbreaks occurring among cannabis users, but the quality of the evidence was very weak.

CONCLUSIONS

Evidence for an association between cannabis use and TB acquisition is weak. The topic warrants further robust primary research including the collection of consistent and accurate exposure information, including cannabis use practices, dose and frequency, and adjustment for confounders.

Pot smokers puffing away lung health

BACKGROUND

Marijuana is the second most commonly used inhalational agent after tobacco. It has been used for therapeutic benefits in cancer, epilepsy, inflammation and pain. Inhalation of marijuana causes reversible and irreversible lung injury.

CASE

We present a 26-year-old female with cough, chest pain, epistaxis, hemoptysis, night sweats and breathlessness few hours after smoking marijuana. Physical exam was positive for tachycardia, tachypnea, and diminished coarse breath sounds. Further investigation revealed elevated white blood cell count, chest X-ray, computed tomography of the chest showed bilateral patchy infiltrates. The patient was managed with short term steroid, as antibiotics alone did not work. Radiological improvement of lung injury was noted within 36-48 h.

CONCLUSION

There is a paucity of treatment guidelines for acute lung injury secondary to marijuana inhalation. We advocate early use of short-term steroids and also more awareness on quitting marijuana smoking to prevent life-threatening complications like myocardial infarction, diffuse alveolar hemorrhage and acute respiratory distress syndrome.

The Relationship Between Tobacco and Cannabis Use: A Review

BACKGROUND

Based on the prevalence and health implications of tobacco and cannabis use, aiming to reduce their use, especially among youth, is a sound objective at both the individual and public health level. A proper understanding of the relationships between tobacco and cannabis use may help to achieve this goal.

OBJECTIVES

To review the relationships between tobacco and cannabis use.

METHODS

A selective review of the literature.

RESULTS

We present an overview of the motivations for tobacco and cannabis use, and their perceived harmfulness. The article then reviews the gateway theory, reverse gateway theory, route of administration theory, and common liability theory. We describe the link between co-use and dependence symptoms, and the substitution phenomenon between tobacco and cannabis use. Three forms of simultaneous use-mulling, blunt smoking, and chasing-and their impacts are explained. We summarize the impact of tobacco use on cannabis (and vice versa) treatment outcomes, and, finally, review new treatments that simultaneously target tobacco and cannabis dependence. Most of the literature reviewed here relates to substance use among adolescents and young adults.

CONCLUSIONS

The use of tobacco and cannabis-two of the most widely used substances around the world-are strongly intertwined in several respects. Both health professionals and researchers should have well-informed views on this issue to better evaluate, understand, inform, and provide care to their patients.

Patients' and clinicians' perspectives of co-use of cannabis and opioids for chronic non-cancer pain management in primary care

BACKGROUND

The prevalence of opioid-associated morbidity and mortality underscores the need for research on non-opioid treatments for chronic non-cancer pain (CNCP). Pain is the most common medical condition for which patients request medical cannabis. Limited research indicates that patients are interested in cannabis as a potential addition to or replacement for opioid medication. This analysis reports on CNCP patient and clinician perceptions about the co-use of cannabis and opioids for CNCP management.

METHODS

We interviewed 23 clinicians and 46 CNCP patients, using semi-structured interview guides, from six safety-net clinics across the San Francisco Bay Area, and 5 key stakeholders involved in CNCP management. We used a modified grounded theory approach to code and analyze transcripts.

RESULTS

CNCP patients described potential benefits of co-use of cannabis and opioids for pain management and concerns about dosing and addictive potential. Patients reported seeking cannabis when unable to obtain prescription opioids. Clinicians stated that their patients reported cannabis being helpful in managing pain symptoms. Clinicians expressed concerns about the potential exacerbation of mental health issues resulting from cannabis use.

CONCLUSION

Clinicians are hampered by a lack of clinically relevant information about cannabis use, efficacy and side-effects. Currently no guidelines exist for clinicians to address opioid and cannabis co-use, or to discuss the risk and benefits of cannabis for CNCP management, including side effects. Cannabis and opioid co-use was commonly reported by patients in our sample, yet rarely addressed during clinical CNCP care. Further research is needed on the risks and benefits of cannabis and opioid co-use.

Marijuana use among adolescent multiple tobacco product users and unique risks of dual tobacco and marijuana use

BACKGROUND

Adolescence is a peak time for uptake of both tobacco and marijuana (dual use). This study aimed to identify clusters of lifetime tobacco and marijuana use patterns and associated risk factors, and to determine whether dual tobacco and marijuana use is uniquely associated with greater risk than use of either tobacco or marijuana alone.

METHOD

High school students participated in a survey during Fall 2014 (N = 976; 68% Hispanic; 57% parental education < high school). Items from national youth surveys were used to measure lifetime and current use of tobacco products, marijuana, alcohol, drug use, and other risk behaviors, and literature-based surveys were used to measure psychological constructs.

RESULTS

Latent Class Analysis identified three clusters of lifetime tobacco use patterns (no tobacco, one or two products, and more than two products), each with a correspondingly distinct profile of risk behaviors; risk escalated with use of more tobacco products. Multinomial modeling characterized personal, environmental, and behavioral correlates of dual lifetime tobacco and marijuana use, including lower parental monitoring, lower grades, higher guilt, higher lifetime alcohol and drug use, and more substance use by friends, in reference to single lifetime use of either tobacco or marijuana.

CONCLUSION

Broader use of tobacco (i.e., more products) was associated with numerous risk factors. Dual lifetime use of tobacco and marijuana was associated with numerous risks compared to single use of either tobacco or marijuana. Longitudinal work is needed to understand temporal relationships between risk variables to determine optimal timing for interventions to reduce harmful behaviors.

The Impact of Cannabis Use Disorder on Suicidal and Nonsuicidal Self-Injury in Iraq/Afghanistan-Era Veterans with and without Mental Health Disorders

The objective of this study was to assess the association between cannabis use disorder (CUD) and self-injury among veterans. As expected, after adjusting for sex, age, sexual orientation, combat exposure, traumatic life events, traumatic brain injury, posttraumatic stress disorder, depression, alcohol use disorder, and noncannabis drug use disorder, CUD was significantly associated with both suicidal (OR = 3.10, p = .045) and nonsuicidal (OR = 5.12, p = .009) self-injury. CUD was the only variable significantly associated with self-injury in all three models examined. These findings are consistent with prior research among civilians and suggest that CUD may also increase veterans' risk for self-injurious behavior.

Legislative Norms to Control Cannabis Use in the Light of Its Prevalence in Czech Republic, Poland, Slovakia, and Hungary

OBJECTIVES

Cannabis control legislation ranks among key measures to prevent social-health impacts of its use. The article qualitatively analyses respective legislation in the Czech Republic, Poland, Slovakia, and Hungary (Visegrad Four, V4) considering level of decriminalisation of cannabis use in relation to current epidemiological situation.

METHODS

Qualitative analysis of the cannabis control legislation in V4 countries from 1995 to 2016 focusing on criminal liability, differentiation of cannabis from other illicit substances, definition of a small amount intended for personal use, sentences for possessing and dealership of the drug. Results: Slovakia, Hungary and Poland share similar restrictive legislative approach throughout the studied period. In the Czech Republic, the situation has been different and since 2010 cannabis has been further decriminalised: possession of defined small amount of drug not being under prosecution and milder sentences for cannabis than for other illicit psychoactive substances.

RESULTS

Slovakia, Hungary and Poland share similar restrictive legislative approach throughout the studied period. In the Czech Republic, the situation has been different and since 2010 cannabis has been further decriminalised: possession of defined small amount of drug not being under prosecution and milder sentences for cannabis than for other illicit psychoactive substances.

CONCLUSION

Although the prevalence of cannabis use among adolescents is the highest in the Czech Republic, partial decriminalisation did not show further increase. Slovakia, Hungary and Poland show different trends in epidemiological situation despite of similar legislative approach. Results indicate that beside legislation other social factors play a role and measures to change attitudes and decrease social tolerance are important.

[Lung cancer in HIV-infected patients]

Until 1996, AIDS was the leading cause of deaths from HIV infection. In 2010, because of introduction of powerful antiretroviral therapies, AIDS represented less than 25% of deaths. Cancer has become the leading cause of death in this population, and, because of smoking and immunosuppression, lung cancer risk is more important than in general population. Furthermore, treatment is more difficult, due to potential interactions between antiretroviral and anticancer therapies, to comorbidities and to tumor aggressiveness. Research will focus on molecular biology, immunotherapies and lung cancer screening in order to improve survival of HIV patients with lung cancer. For all these reasons, HIV patients must be included in clinical trials.

The consequences of chronic cannabis smoking in vulnerable adolescents

Cannabis, like the mythic shape-shifter, presents in various guises, morphing with the perspective and context of the observer. Arguments about cannabis are confused by a myriad of debates-medical, social, ethical and political-as if a single conceptual umbrella can capture the variety and granularity of marijuana-related issues. This paper responds to marijuana use as it is commonly practised by youth in Australia. It has little to say about synthetic cannabinoids, specific medicinal cannabinoids, or medicinal properties of marijuana. We address those adolescents genetically and environmentally vulnerable to mental illness, with specific emphasis on indigenous and neurodevelopmentally impaired young people who show patterns of usage and response very different to adults and more resilient members of the population. Specifically, the practice of mixing tobacco with marijuana by aboriginal youth, and the resultant coalition of dependencies, will likely presage a rise in pulmonary and central nervous system pathology over the coming decades. Aboriginal youth begin using earlier, persist longer, and take greater quantities of cannabis than non-indigenous youth. This paper recommends practical interventions to reduce the multiple health consequences of chronic cannabis use in young people, especially indigenous young people.

Marijuana smoke induces severe pulmonary hyperresponsiveness, inflammation, and emphysema in a predictive mouse model not via CB1 receptor activation

Sporadic clinical reports suggested that marijuana smoking induces spontaneous pneumothorax, but no animal models were available to validate these observations and to study the underlying mechanisms. Therefore, we performed a systematic study in CD1 mice as a predictive animal model and assessed the pathophysiological alterations in response to 4-mo-long whole body marijuana smoke with integrative methodologies in comparison with tobacco smoke. Bronchial responsiveness was measured with unrestrained whole body plethysmography, cell profile in the bronchoalveolar lavage fluid with flow cytometry, myeloperoxidase activity with spectrophotometry, inflammatory cytokines with ELISA, and histopathological alterations with light microscopy. Daily marijuana inhalation evoked severe bronchial hyperreactivity after a week. Characteristic perivascular/peribronchial edema, atelectasis, apical emphysema, and neutrophil and macrophage infiltration developed after 1 mo of marijuana smoking; lymphocyte accumulation after 2 mo; macrophage-like giant cells, irregular or destroyed bronchial mucosa, goblet cell hyperplasia after 3 mo; and severe atelectasis, emphysema, obstructed or damaged bronchioles, and endothelial proliferation at 4 mo. Myeloperoxidase activity, inflammatory cell, and cytokine profile correlated with these changes. Airway hyperresponsiveness and inflammation were not altered in mice lacking the CB1 cannabinoid receptor. In comparison, tobacco smoke induced hyperresponsiveness after 2 mo and significantly later caused inflammatory cell infiltration/activation with only mild emphysema. We provide the first systematic and comparative experimental evidence that marijuana causes severe airway hyperresponsiveness, inflammation, tissue destruction, and emphysema, which are not mediated by the CB1 receptor.

The Use of Medical Marijuana in Cancer

The use of medical marijuana in cancer care presents a dilemma for both patients and physicians. The scientific evidence is evolving, yet much of the known information is still insufficient to adequately inform patients as to risks and benefits. In addition, evidence-based dosing and administration information on medical marijuana is lacking. Medical marijuana is now legal, on some level, in 24 states plus the District of Columbia, yet is not legal on the federal level. This review addresses the current state of the research, including potential indications, risks and adverse effects, preliminary data on anticancer effects, as well as legal and quality issues. A summary of the clinical trials underway on medical marijuana in the oncology setting is discussed.

Patterns of marijuana and tobacco use associated with suboptimal self-rated health among US adult ever users of marijuana

The purpose of this study was to examine the patterns of marijuana and tobacco use and their associations with suboptimal self-rated health (SRH) among US adults who reported "ever, even once, using marijuana or hashish." Data came from the 2009-2012 National Health and Nutrition Examination Survey, restricting to respondents aged 20 years and older who reported using marijuana at least once in their lifetime (n = 3,210). We assessed the age-adjusted prevalence of mutually exclusive groups of regular (at least once a month for more than one year) and non-regular marijuana smoking by current (serum cotinine ≥ 3.08 ng/mL) and not current use of tobacco. Suboptimal SRH status was defined as "fair" or "poor" in response to the question "Would you say that in general your health is excellent, very good, good, fair, or poor?" We produced prevalence ratios with multivariable log-linear regression models. Among ever users of marijuana, the age-adjusted prevalence of regular marijuana smoking with current tobacco use, non-regular marijuana smoking with current tobacco use, and regular marijuana smoking without current tobacco use was 24.7%, 15.2%, and 21.1%, respectively. When compared to non-regular marijuana smokers without current tobacco use, the adjusted prevalence ratio for reporting suboptimal SRH was 1.98 (95% CI: 1.50-2.61), 1.82 (95% CI: 1.40-2.37), and 1.34 (95% CI: 1.05-1.69), respectively. In conclusion, among adult ever users of marijuana, current tobacco use is high and strongly associated with suboptimal SRH; regular marijuana smoking with or without current tobacco use is significantly associated with suboptimal SRH.

Cannabis use disorder and suicide attempts in Iraq/Afghanistan-era veterans

The objective of the present research was to examine the association between lifetime cannabis use disorder (CUD), current suicidal ideation, and lifetime history of suicide attempts in a large and diverse sample of Iraq/Afghanistan-era veterans (N = 3233) using a battery of well-validated instruments. As expected, CUD was associated with both current suicidal ideation (OR = 1.683, p = 0.008) and lifetime suicide attempts (OR = 2.306, p < 0.0001), even after accounting for the effects of sex, posttraumatic stress disorder, depression, alcohol use disorder, non-cannabis drug use disorder, history of childhood sexual abuse, and combat exposure. Thus, the findings from the present study suggest that CUD may be a unique predictor of suicide attempts among Iraq/Afghanistan-era veterans; however, a significant limitation of the present study was its cross-sectional design. Prospective research aimed at understanding the complex relationship between CUD, mental health problems, and suicidal behavior among veterans is clearly needed at the present time.

High-intensity cannabis use and HIV clinical outcomes among HIV-positive people who use illicit drugs in Vancouver, Canada

BACKGROUND

Reforms to the legal status of medical and non-medical cannabis are underway in many jurisdictions, including Canada, as are renewed efforts to scale-up HIV treatment-as-prevention (TasP) initiatives. It has been suggested that high-intensity cannabis use may be associated with sub-optimal HIV treatment outcomes. Thus, using data from a setting with a community-wide treatment-as-prevention (TasP) initiative coinciding with increasing access to medical cannabis, we sought to investigate the possible impact of high-intensity cannabis use on HIV clinical outcomes.

METHODS

Data was derived from the ACCESS study, a prospective cohort of HIV-positive people who use illicit drugs (PWUD) in Vancouver, Canada. Cohort data was confidentially linked to comprehensive clinical profiles, including records of all antiretroviral therapy (ART) dispensations and longitudinal plasma HIV-1 RNA viral load (VL) monitoring. We used generalized estimating equations (GEEs) to estimate the longitudinal bivariable and multivariable relationships between at least daily cannabis use and two key clinical outcomes: overall engagement in ART care, and achieving a non-detectable VL among ART-exposed participants.

RESULTS

Between December 2005 and June 2015, 874 HIV-positive PWUD (304 [35%] non-male) were included in this study. In total, 788 (90%) were engaged in HIV care at least once over the study period, of whom 670 (85%) achieved non-detectable VL at least once. In multivariable analyses, ≥ daily cannabis use did not predict lower odds of ART care (Adjusted Odds Ratio [AOR]: 1.02, 95% confidence interval [CI]: 0.77-1.36) or VL non-detectability among ART-exposed (AOR: 0.96, 95% CI: 0.75-1.21). Upon testing for potential interactions, ≥ daily cannabis use was found to be negatively associated with ART engagement during periods of binge alcohol use (p<0.05).

CONCLUSION

With the exception of frequent cannabis use during periods of binge alcohol use, our results showed no statistically significant impact of daily cannabis use on the likelihood of ART care or VL non-detectability among ART-exposed HIV-positive PWUD. These findings are reassuring in light of the impending legalization of cannabis in Canada and ongoing efforts to expand TasP initiatives.

Counseling Parents and Teens About Marijuana Use in the Era of Legalization of Marijuana

Many states have recently made significant changes to their legislation making recreational and/or medical marijuana use by adults legal. Although these laws, for the most part, have not targeted the adolescent population, they have created an environment in which marijuana increasingly is seen as acceptable, safe, and therapeutic. This clinical report offers guidance to the practicing pediatrician based on existing evidence and expert opinion/consensus of the American Academy of Pediatrics regarding anticipatory guidance and counseling to teenagers and their parents about marijuana and its use. The recently published technical report provides the detailed evidence and references regarding the research on which the information in this clinical report is based.

Medical Marijuana: Just the Beginning of a Long, Strange Trip?

Medical marijuana continues to gain acceptance and become legalized in many states. Various species of the marijuana plant have been cultivated, and this plant can contain up to 100 active compounds known as cannabinoids. Two cannabinoids seem the most clinically relevant: Δ9-tetrahydrocannabinol (THC), which tends to produce the psychotropic effects commonly associated with marijuana, and cannabidiol (CBD), which may produce therapeutic effects without appreciable psychoactive properties. Smoking marijuana, or ingesting extracts from the whole plant orally (in baked goods, teas, and so forth), introduces variable amounts of THC, CBD, and other minor cannabinoids into the systemic circulation, where they ultimately reach the central and peripheral nervous systems. Alternatively, products containing THC, CBD, or a combination of both compounds, can be ingested as oral tablets or via sprays applied to the oral mucosal membranes. These products may provide a more predictable method for delivering a known amount of specific cannabinoids into the body. Although there is still a need for randomized controlled trials, preliminary studies have suggested that medical marijuana and related cannabinoids may be beneficial in treating people with chronic pain, inflammation, spasticity, and other conditions seen commonly in physical therapist practice. Physical therapists, therefore, should be aware of the options that are available for patients considering medical marijuana and should be ready to provide information for these patients. Clinicians also should be aware that marijuana can produce untoward effects on cognition, coordination, balance, and cardiovascular and pulmonary function and should be vigilant for any problems that may arise if patients are using cannabinoids during physical rehabilitation.

Inflammatory mechanisms in patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is associated with chronic inflammation affecting predominantly the lung parenchyma and peripheral airways that results in largely irreversible and progressive airflow limitation. This inflammation is characterized by increased numbers of alveolar macrophages, neutrophils, T lymphocytes (predominantly TC1, TH1, and TH17 cells), and innate lymphoid cells recruited from the circulation. These cells and structural cells, including epithelial and endothelial cells and fibroblasts, secrete a variety of proinflammatory mediators, including cytokines, chemokines, growth factors, and lipid mediators. Although most patients with COPD have a predominantly neutrophilic inflammation, some have an increase in eosinophil counts, which might be orchestrated by TH2 cells and type 2 innate lymphoid cells though release of IL-33 from epithelial cells. These patients might be more responsive to corticosteroids and bronchodilators. Oxidative stress plays a key role in driving COPD-related inflammation, even in ex-smokers, and might result in activation of the proinflammatory transcription factor nuclear factor κB (NF-κB), impaired antiprotease defenses, DNA damage, cellular senescence, autoantibody generation, and corticosteroid resistance though inactivation of histone deacetylase 2. Systemic inflammation is also found in patients with COPD and can worsen comorbidities, such as cardiovascular diseases, diabetes, and osteoporosis. Accelerated aging in the lungs of patients with COPD can also generate inflammatory protein release from senescent cells in the lung. In the future, it will be important to recognize phenotypes of patients with optimal responses to more specific therapies, and development of biomarkers that identify the therapeutic phenotypes will be important.

Risks associated with the non-medicinal use of cannabis

BACKGROUND

Cannabis is the most commonly consumed illicit drug around the world; in Germany, about 4.5% of all adults use it each year. Intense cannabis use is associated with health risks. Evidence-based treatments are available for health problems caused by cannabis use.

METHODS

Selective literature review based on a search of the PubMed database, with special emphasis on systematic reviews, meta-analyses, cohort studies, randomized controlled trials (RCTs), case-control studies, and treatment guidelines.

RESULTS

The delta-9-tetrahydrocannabinol content of cannabis products is rising around the world as a result of plant breeding, while cannabidiol, in contrast, is often no longer detectable. Various medical conditions can arise acutely after cannabis use, depending on the user's age, dose, frequency, mode and situation of use, and individual disposition; these include panic attacks, psychotic symptoms, deficient attention, impaired concentration, motor incoordination, and nausea. In particular, intense use of high doses of cannabis over many years, and the initiation of cannabis use in adolescence, can be associated with substance dependence (DSM-5; ICD-10), specific withdrawal symptoms, cognitive impairment, affective disorders, psychosis, anxiety disorders, and physical disease outside the brain (mainly respiratory and cardiovascular conditions). At present, the most effective way to treat cannabis dependence involves a combination of motivational encouragement, cognitive behavioral therapy, and contingency management (level 1a evidence). For adolescents, family therapy is also recommended (level 1a evidence). No pharmacological treatments can be recommended to date, as evidence for their efficacy is lacking.

CONCLUSION

Further research is needed to elucidate the causal relationships between intense cannabis use and potential damage to physical and mental health. Health problems due to cannabis use can be effectively treated.

Marijuana use trajectories during college predict health outcomes nine years post-matriculation

BACKGROUND

Several studies have linked marijuana use with a variety of health outcomes among young adults. Information about marijuana's long-term health effects is critically needed.

METHODS

Data are from a ten-year study of 1253 young adults originally recruited as first-year college students and assessed annually thereafter. Six trajectories of marijuana use during college (Non-Use, Low-Stable, Early-Decline, College-Peak, Late-Increase, Chronic) were previously derived using latent variable growth mixture modeling. Nine health outcomes assessed in Year 10 (modal age 27) were regressed on a group membership variable for the six group trajectories, holding constant demographics, baseline health status, and alcohol and tobacco trajectory group membership.

RESULTS

Marijuana trajectory groups differed significantly on seven of the nine outcomes (functional impairment due to injury, illness, or emotional problems; psychological distress; subjective well-being; and mental and physical health service utilization; all ps<.001), but not on general health rating or body mass index. Non-users fared better than the Late-Increase and Chronic groups on most physical and mental health outcomes. The declining groups (Early-Decline, College-Peak) fared better than the Chronic group on mental health outcomes. The Late-Increase group fared significantly worse than the stable groups (Non-Use, Low-Stable, Chronic) on both physical and mental health outcomes.

CONCLUSIONS

Even occasional or time-limited marijuana use might have adverse effects on physical and mental health, perhaps enduring after several years of moderation or abstinence. Reducing marijuana use frequency might mitigate such effects. Individuals who escalate their marijuana use in their early twenties might be at especially high risk for adverse outcomes.

Inhaled Cannabis for Chronic Neuropathic Pain: A Meta-analysis of Individual Patient Data

Chronic neuropathic pain, the most frequent condition affecting the peripheral nervous system, remains underdiagnosed and difficult to treat. Inhaled cannabis may alleviate chronic neuropathic pain. Our objective was to synthesize the evidence on the use of inhaled cannabis for chronic neuropathic pain. We performed a systematic review and a meta-analysis of individual patient data. We registered our protocol with PROSPERO CRD42011001182. We searched in Cochrane Central, PubMed, EMBASE, and AMED. We considered all randomized controlled trials investigating chronic painful neuropathy and comparing inhaled cannabis with placebo. We pooled treatment effects following a hierarchical random-effects Bayesian responder model for the population-averaged subject-specific effect. Our evidence synthesis of individual patient data from 178 participants with 405 observed responses in 5 randomized controlled trials following patients for days to weeks provides evidence that inhaled cannabis results in short-term reductions in chronic neuropathic pain for 1 in every 5 to 6 patients treated (number needed to treat = 5.6 with a Bayesian 95% credible interval ranging between 3.4 and 14). Our inferences were insensitive to model assumptions, priors, and parameter choices. We caution that the small number of studies and participants, the short follow-up, shortcomings in allocation concealment, and considerable attrition limit the conclusions that can be drawn from the review. The Bayes factor is 332, corresponding to a posterior probability of effect of 99.7%.

PERSPECTIVE

This novel Bayesian meta-analysis of individual patient data from 5 randomized trials suggests that inhaled cannabis may provide short-term relief for 1 in 5 to 6 patients with neuropathic pain. Pragmatic trials are needed to evaluate the long-term benefits and risks of this treatment.