Evidence map›Paper›PMID 26940105›Full record

Observational studyBMJ open2016

Association of cannabis use with hospital admission and antipsychotic treatment failure in first episode psychosis: an observational study.

Rashmi Patel, Robin Wilson, Richard Jackson, Michael Ball, Hitesh Shetty, Matthew Broadbent, Robert Stewart, Philip McGuire, Sagnik Bhattacharyya

Registry-linked trialAbstract readObservational Study
PubMed Full text at PMC Publisher
In one paragraph

Observational study in BMJ open, 2016. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT07245212 (Testing the Efficacy of the Cannabis Clinic for Patients With Psychosis), which is not on this map. Cited by 79 papers, 6 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
79citing papers in PubMed, 6 pooled it
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

NCT07245212 nanot yet recruitingnot on this mapstarted 2025, after this paper: background citation

Testing the Efficacy of the Cannabis Clinic for Patients With Psychosis (CCP) Intervention for Cannabis Use Reduction/Cessation in Patients With First Episode Psychosis

TypeinterventionalSponsorKing's College LondonRan2025 to 2028Enrolled80ConditionsPsychosis, Cannabis Use Disorder, First Episode Psychosis (FEP)ArmsCCP Intervention
3 · Its place in the literature

Who cites it

79 citing papers in PubMed, 6 syntheses or guidelines pooled it.

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  15. Real-world effectiveness of antipsychotic medication in relapse prevention after cannabis-induced psychosis.The British journal of psychiatry : the journal of mental science · 2026
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19 more citing papers are in PubMed but not listed here.

4 · The record

Corrections and comments

5 · Who and what money

Authors and funding

9 authors.

Rashmi PatelDepartment of Psychosis Studies, King's College London, Institute of Psychiatry, Psychology & Neuroscience, London, UK.ORCID http://orcid.org/0000-0002-9259-8788
Robin WilsonDepartment of Psychosis Studies, King's College London, Institute of Psychiatry, Psychology & Neuroscience, London, UK.
Richard JacksonDepartment of Psychological Medicine, King's College London, Institute of Psychiatry, Psychology & Neuroscience, London, UK.
Michael BallDepartment of Psychological Medicine, King's College London, Institute of Psychiatry, Psychology & Neuroscience, London, UK.
Hitesh ShettySouth London and Maudsley NHS Foundation Trust, Biomedical Research Centre Nucleus, London, UK.
Matthew BroadbentSouth London and Maudsley NHS Foundation Trust, Biomedical Research Centre Nucleus, London, UK.
Robert StewartDepartment of Psychological Medicine, King's College London, Institute of Psychiatry, Psychology & Neuroscience, London, UK.
Philip McGuireDepartment of Psychosis Studies, King's College London, Institute of Psychiatry, Psychology & Neuroscience, London, UK.
Sagnik BhattacharyyaDepartment of Psychosis Studies, King's College London, Institute of Psychiatry, Psychology & Neuroscience, London, UK.

Funding

Department of Health NIHR-CS-011-001Medical Research Council MR/J012149/1Medical Research Council MR/K002813/1
6 · The paper itself

Abstract

objectiveTo investigate whether cannabis use is associated with increased risk of relapse, as indexed by number of hospital admissions, and whether antipsychotic treatment failure, as indexed by number of unique antipsychotics prescribed, may mediate this effect in a large data set of patients with first episode psychosis (FEP).

designObservational study with exploratory mediation analysis.

settingAnonymised electronic mental health record data from the South London and Maudsley NHS Foundation Trust.

participants2026 people presenting to early intervention services with FEP. EXPOSURE: Cannabis use at presentation, identified using natural language processing.

main outcome measuresadmission to psychiatric hospital and clozapine prescription up to 5 years following presentation. MEDIATOR: Number of unique antipsychotics prescribed.

resultsCannabis use was present in 46.3% of the sample at first presentation and was particularly common in patients who were 16-25, male and single. It was associated with increased frequency of hospital admission (incidence rate ratio 1.50, 95% CI 1.25 to 1.80), increased likelihood of compulsory admission (OR 1.55, 1.16 to 2.08) and greater number of days spent in hospital (β coefficient 35.1 days, 12.1 to 58.1). The number of unique antipsychotics prescribed, mediated increased frequency of hospital admission (natural indirect effect 1.09, 95% CI 1.01 to 1.18; total effect 1.50, 1.21 to 1.87), increased likelihood of compulsory admission (natural indirect effect (NIE) 1.27, 1.03 to 1.58; total effect (TE) 1.76, 0.81 to 3.84) and greater number of days spent in hospital (NIE 17.9, 2.4 to 33.4; TE 34.8, 11.6 to 58.1).

conclusionsCannabis use in patients with FEP was associated with an increased likelihood of hospital admission. This was linked to the prescription of several different antipsychotic drugs, indicating clinical judgement of antipsychotic treatment failure. Together, this suggests that cannabis use might be associated with worse clinical outcomes in psychosis by contributing towards failure of antipsychotic treatment.

Indexed as

AdolescentAdultAntipsychotic AgentsFemaleHumansLogistic ModelsLondonMaleMarijuana SmokingMultivariate AnalysisPatient AdmissionPsychotic DisordersRegistriesTreatment FailureYoung AdultAntipsychotic AgentsCannabisCRISFEPMediation analysisNatural Language ProcessingNLP

Identifiers

PMID26940105
PMCPMC4785290

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Registered trials

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.