Among 517 hospitalized patients with schizophrenia or schizoaffective disorder, cannabis users had shorter hospital stays than non-users, but this difference disappeared after controlling for covariates.
Psychiatrists, inpatient mental health providers, and psychosis researchers.
Cannabis use did not predict worse hospitalization outcomes after covariate adjustment
What the researchers found
Cannabis-only users (n=55) had shorter mean hospital stays than non-substance users (n=462): 6.15 vs. 8.66 days. However, this difference was no longer significant after controlling for covariates (p=0.15). The number of psychiatric admissions did not differ between groups.
Why it matters
Contrary to common assumptions, cannabis use did not predict worse hospitalization outcomes in this population, suggesting the relationship between cannabis and schizophrenia course may be more nuanced than assumed.
The numbers in context
Cannabis users: 55. Non-users: 462. Mean LOS cannabis group: 6.15 days (SD 5.32). Mean LOS non-users: 8.66 days (SD 11.14). Mean admissions: 1.84. Unadjusted p=0.035; adjusted p=0.15.
How the study worked
Retrospective comparison of 55 cannabis-only users and 462 non-substance users hospitalized with a primary diagnosis of schizophrenia or schizoaffective disorder. Used Wilcoxon-Mann-Whitney tests, ANOVA, and Poisson regression with covariate adjustment.
What this study cannot tell us
Small cannabis-only group (n=55). Retrospective design. Cannot account for cannabis potency, frequency, or timing relative to symptoms. Excluded polydrug users, limiting generalizability.
How to read the evidence
Retrospective study with small cannabis group and limited covariate data.
When this study was published
Published in 2021.
The bigger picture
The finding that cannabis use did not worsen hospitalization metrics in schizophrenia challenges the assumption that cannabis universally worsens psychotic disorder outcomes.
Questions still open
- What covariates drove the loss of significance in adjusted models? Does the type of cannabis (high-THC vs. balanced) matter for hospitalization outcomes in schizophrenia?
Common questions
Does cannabis use lead to longer psychiatric hospital stays?
Did cannabis users get hospitalized more often?
Read the original research
Psychiatric Hospitalization and Length of Stay Differences in Cannabis Users and Non-Users with a Primary Discharge Diagnosis of Schizophrenia or Schizoaffective Disorder.
Substance use & misuse, 56(11), 1736-1739
Citation
Williams, Steven R; Agapoff, James R; Jalan, Devesh; Hishinuma, Earl S; Kida, Lauren E. (2021). Psychiatric Hospitalization and Length of Stay Differences in Cannabis Users and Non-Users with a Primary Discharge Diagnosis of Schizophrenia or Schizoaffective Disorder.. Substance use & misuse, 56(11), 1736-1739. https://doi.org/10.1080/10826084.2021.1949615
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