Association of cannabis use with hospital admission and antipsychotic treatment failure in first episode psychosis: an observational study
R. Patel, R. Wilson, R. Jackson, M. Ball, H. Shetty, M. Broadbent, R. Stewart, P. McGuire, Sagnik Bhattacharyya
BMJ Open 2016 DOI: 10.1136/bmjopen-2015-009888 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational study with exploratory mediation analysis Peer reviewed |
|---|---|
| Sample size | 2,026 |
| Population | People presenting to early intervention services with first episode psychosis in the South London and Maudsley NHS Foundation Trust |
| Duration | Up to 5 years following presentation |
| Topics | Cannabis |
| Key findings | Cannabis use at first presentation with psychosis was associated with increased hospital admission frequency, compulsory admission, and days spent in hospital. The number of unique antipsychotics prescribed partially mediated these associations, suggesting that cannabis use may be linked to worse clinical outcomes by contributing to antipsychotic treatment failure. |
Abstract
Objective: To 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).
Design: Observational study with exploratory mediation analysis.
Setting: Anonymised electronic mental health record data from the South London and Maudsley NHS Foundation Trust.
Participants: 2026 people presenting to early intervention services with FEP. Exposure Cannabis use at presentation, identified using natural language processing. Main outcome measures admission to psychiatric hospital and clozapine prescription up to 5 years following presentation. Mediator Number of unique antipsychotics prescribed.
Results: Cannabis 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).
Conclusions: Cannabis 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.
Comparable studies
Other observational and cohort studies on cannabis, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| High-potency cannabis and the risk of psychosis People with first episode of psychosis and healthy controls from the local population | 2009 | Case-control study | n = 454 |
| Ayahuasca-Assisted Therapy for Addiction: Results from a Preliminary Observational Study in Canada Rural aboriginal population | 2013 | Observational study | |
| Impaired cognitive performance in drug free users of recreational ecstasy (MDMA) Otherwise healthy young people | 2000 | Observational | |
| Continued cannabis use and risk of incidence and persistence of psychotic symptoms: 10 year follow-up cohort study Individuals from the general population in Germany aged 14-24 at baseline | 2011 | Observational cohort | n = 1,923 |
| Cannabis-induced psychosis and subsequent schizophrenia-spectrum disorders: follow-up study of 535 incident cases Patients treated for cannabis-induced psychotic symptoms in Denmark between 1994 and... | 2005 | Observational cohort | n = 535 |
Citations in the library
Cited by 29
- Poor medication adherence and risk of relapse associated with continued cannabis use in patients with first-episode psychosis: a prospective analysis The Lancet Psychiatry July 10, 2017
- Increased hippocampal engagement during learning as a marker of sensitivity to psychotomimetic effects ofδ-9-THC Psychological Medicine March 5, 2018
- Randomized Laboratory Study of Single-Dose Cannabis, Dronabinol, and Placebo in Patients With Schizophrenia and Cannabis Use Disorder Schizophrenia Bulletin June 20, 2024
- Exploration of cannabis use and polygenic risk scores on the psychotic symptom progression of a FEP cohort Psychiatry Research May 8, 2023
- Eye movements in patients in early psychosis with and without a history of cannabis use Schizophrenia May 12, 2021
and 24 more in the library
Cites 6
- Continued cannabis use and risk of incidence and persistence of psychotic symptoms: 10 year follow-up cohort study BMJ March 1, 2011
- Effects of cannabis use on outcomes of psychotic disorders: systematic review The British Journal of Psychiatry October 31, 2008
- Cannabis use and first-episode psychosis: relationship with manic and psychotic symptoms, and with age at presentation Psychological Medicine May 24, 2013
- Continued versus discontinued cannabis use in patients with psychosis: a systematic review and meta-analysis. The Lancet Psychiatry March 1, 2016
- Cannabis and First-Episode Psychosis: Different Long-term Outcomes Depending on Continued or Discontinued Use Schizophrenia Bulletin November 13, 2009
and 1 more in the library