Effect of comorbid Cannabis use on risk of readmission in first-episode psychosis: data from two cohorts employing complementary methodology.

Presentation First Author: 
Sagnik Bhattacharyya

Use of cannabis, the most commonly used illicit drug worldwide, has been linked to increased risk of relapse of illness in patients with psychosis who continue to use the drug. However, most studies investigating the effect of cannabis use on outcome are limited by, either a small sample size, short follow-up duration or outcome measures that rely on change of symptom severity. The purpose of this presentation is to present the results from two cohorts of patients with first episode psychosis (FEP) in South London, investigating the effects of cannabis use at presentation as well as ongoing use on subsequent admission to hospital, employing complementary approaches.Methods: Cohort 1 examined the electronic health records of over 2000 patients with FEP using natural language processing to investigate the effect of documented cannabis use around onset of illness on risk of subsequent hospital admission. Cohort 2 investigated the effect of ongoing cannabis use on hospital admission in a prospectively recruited FEP cohort (n=95) followed-up through face-to-face interviews. Logistic and Linear regression analyses were carried out.Results: Odds of readmission to hospital was significantly greater in FEP patients with history of cannabis use at onset of illness. Odds of readmission and number of readmissions were significantly greater and time to readmission significantly shorter in those FEP patients with ongoing cannabis use during follow-up period. Conclusions: Data from these prospective cohorts employing complementary approaches highlight the importance of ongoing cannabis use on risk of readmission in psychosis and suggest the need for prevention strategies.

Conference Name: 
Presentation Date: 
January, 2015
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