Psychotic disorders hospitalizations associated with cannabis abuse or dependence: A nationwide big data analysis

Int J Methods Psychiatr Res. 2020 Mar;29(1):e1813. doi: 10.1002/mpr.1813. Epub 2019 Dec 5.


Objectives: We aimed to describe and correlate the hospital panorama of psychotic disorders (PD) with cannabis use (CU) trends in all Portuguese public hospitals.

Methods: We conducted a retrospective observational study that analysed all hospitalizations that occurred in Portuguese public hospitals from 2000 to 2015. Hospitalizations with a primary diagnosis of PD or schizophrenia were selected based on Clinical Classification Software diagnostic single-level 659. Episodes associated with CU were identified by the International Classification of Diseases Version 9, Clinical Modification code 304.3/305.2 that correspond to cannabis dependence/cannabis abuse.

Results: The number of hospitalizations with a primary diagnosis of PD and schizophrenia associated with CU rose 29.4 times during the study period, from 20 to 588 hospitalizations yearly (2000 and 2015, respectively) with a total of 3,233 hospitalizations and an average episode cost of €3,500. Male patients represented 89.8% of all episodes, and the mean/median age at discharge were 30.66/29.00 years, respectively. From all hospitalizations with a primary diagnosis of PD or schizophrenia, the ones with a secondary diagnosis of CU rose from 0.87% in 2000 to 10.60% in 2015.

Conclusions: The increase on secondary diagnosis coding and the change on cannabis patterns of consumption in Portuguese population with an increasing frequency of moderate/high dosage cannabis consumers may explain the rise on PD hospitalizations.

Keywords: cannabis; epidemiology; health service; psychoses; public mental health.

Publication types

  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Diagnosis, Dual (Psychiatry)
  • Female
  • Hospitalization / statistics & numerical data*
  • Hospitals, Public / statistics & numerical data*
  • Humans
  • Male
  • Marijuana Abuse / complications
  • Marijuana Abuse / epidemiology*
  • Portugal / epidemiology
  • Psychotic Disorders / epidemiology*
  • Psychotic Disorders / etiology
  • Retrospective Studies
  • Schizophrenia / epidemiology*