Cannabis use the week before admission to psychiatric in-patient service as a marker of severity

Abstract

Objective

To evaluate if cannabis dose recorded as standard joint unit (SJU) consumed before admission and other related factors have an influence on psychiatric inpatient's symptom severity and clinical outcomes.

Methods

Cross-sectional study in an acute psychiatric inpatient unit including 106 individuals. Quantity of cannabis was measured as SJU and symptoms severity through the Brief Psychiatric Rating Scale (BPRS). Secondary outcomes (e.g. length of stay) were also assessed. Bivariate analyses and multivariate analyses were performed to determine the effect of SJU consumed before admission on measures of clinical severity.

Results

Point prevalence of cannabis use before admission was 25.5%. Mean BPRS score was 55.8 (SD = 16.1); and 62.9 (SD = 11.1) among cannabis users. A low degree positive correlation between SJU consumed the week before admission and BPRS score (r_s = 0.28, p = 0.03) was found. In the multivariate analyses both main diagnostic group, Schizophrenia and other psychotic disorders vs. others (Bipolar and Unipolar Affective Disorders and Addictive disorders) (B = 8.327; 95% CI 4.976–11.677) and need of PRN (“pre re nata” or when necessary) administration of antipsychotics and benzodiazepines (B = 12.13; 95% CI 6.868–17.393) were significant predictors, both increasing BPRS score.

Conclusions

The study did not find a correlation between SJU consumed last week and psychiatric severity. On the other hand, individuals with psychotic disorders reported a higher prevalence of cannabis use the week before admission and displayed higher BPRS scores, which points to the need for the development of tailored interventions for high-risk groups. The SJU is a useful quantification tool suitable for further clinical research.

Introduction

The European Monitoring Center for Drugs and Drug Addiction 2019 statistical bulletin reported that the prevalence of cannabis use among people aged 15–34 in Spain is 18,3% (Ng et al., 2007); according to the EDADES report (2019) from the Spanish observatory for drugs and addictions (OEDA) cannabis use prevalence in Spain has increased from 14,5% in 1995 to 35,2% in 2017 (Delegación del Gobierno para el Plan Nacional sobre Drogas, 2019). More so global tendencies point out cannabis use will increase furthermore, making it a priority to determine its medical and societal implications.

A recent study that identified more than 2,8 million admissions with documented cannabis abuse/dependence found that approximately one out of five patients was admitted for a primary diagnosis of a mental health disorder (Charilaou et al., 2017). Cannabis seems to be strongly associated with mental health disorders as a whole and when the most common disorders are examined individually (Lai and Sitharthan, 2012). It seems that besides the shared vulnerabilities between disorders, the presence of a mental illness itself is a vulnerability factor for addiction, despite the heterogeneity across comorbidities (Lowe et al., 2019).

A study looking at over 17,000 individuals associated cannabis use not only with psychiatric hospitalization, but found a dose–response relationship in which heavy users had an odds ratio for hospitalization of 6.2 (vs. 1.6 for incidental users) (Schubart et al., 2011). Even more, it has been shown that co-occurrence of cannabis use disorder (CUD) and psychiatric disorders is associated with greater symptom severity, poorer treatment outcomes, and greater health service use relative to patients without a CUD co-morbidity (Stinson et al., 2006). The relationship between cannabis use and severity of psychotic and affective disorders has been previously studied for inpatient populations (Balan Moshe et al., 2018; Colizzi et al., 2018; Rylander et al., 2018). One study assessed the influence of cannabis use on psychotic and affective symptom severity, finding that users had more prominent psychotic symptoms (Katz et al., 2010). Additionally, there seems to be an association between CUD and an almost three fold increase in the odds of mania symptoms (Gibbs et al., 2015).

Although quantities seem to influence cannabis-related outcomes, until now its use has been mainly assessed by frequency. To our knowledge there are no studies using a standardized measure for quantification of cannabis to assess its impact on symptom severity in clinical populations. On 2017 the Standard Joint Unit (SJU) was set by our group based on quantity of 9-Tetrahydrocannabidol (9-Δ-THC) found in cannabis (Casajuana et al., 2018):1 SJU = 1 joint = 0.25 g of cannabis = 7 mg of 9-Δ-THC (Casajuana Kögel et al., 2017), allowing for a more systematic assessment of cannabis use. It is a useful tool to measure the dose of used drug in a similar way to the standard drink unit, and similarly a field work was done to define the median dose by unit consumed. The SJU was obtained by assessing amount of 9-Δ-THC and CBD in 315 joints (marihuana and hashish) donated voluntarily by 492 participants in universities, leisure spaces, mental health services and cannabis clubs in Barcelona. Making the SJU useful for clinical, epidemiological and research purposes in our sample. Furthermore, it can be used to measure both frequency and quantity of use (Casajuana Kögel et al., 2017).

First of all, this study intended to evaluate if the dose of cannabis (measured as SJU) consumed the week before admission and other co-factors had an impact on acute psychiatric inpatient's symptom severity. As a secondary objective, we also intended to evaluate its impact on other indirect indicators of clinical severity (need for physical restraint and PRN administration of medication, and length of stay). Lastly, we planned to explore the quantity of cannabis consumed before admission in an acute inpatient psychiatric unit. According to previous literature and clinical experience, our main hypothesis was that higher quantity of cannabis consumed the week before admission would be associated with higher clinical severity.