title: A retrospective analysis of cannabis use in a cohort of mentally ill patients in Sri Lanka and its implications on policy development.
abstract: BACKGROUND
  Several epidemiological studies have shown that cannabis; the most widely used illegal drug in the world, is associated with schizophrenia spectrum disorders (SSD).
  
  
  OBJECTIVE
  To assess the characteristics of cannabis use and its association with SSD in a cohort of psychiatrically ill patients and discuss the implications for policy development
  
  
  METHODS
  This is a retrospective analytical study of a cohort of psychiatric patients who received treatment in the psychiatry unit of the Provincial General Hospital, Ratnapura, Sri Lanka over five years (2000 - 2004). The schizophrenia spectrum disorders defined in this article include schizophrenia and the schizoaffective disorders.
  
  
  RESULTS
  A total of 3644 patient records were analyzed. The percentage of self reported life time cannabis (LTC) use was 2.83% (103, all males). Sixteen percent (576) of the total cohort was diagnosed with SSD by 2009. Male sex and LTC use were significantly associated with SSD (p < 0.01 and 0.001 respectively). In the majority (91.5%), cannabis use preceded the diagnosis. There were 17(16.5%) patients diagnosed as cannabis induced psychosis and 7 (41.2%) of them were subsequently diagnosed as SSD. This group was significantly more likely to have had a past psychiatric consultation, but other demographic and clinical correlates did not differ from the rest of the LTC users.
  
  
  CONCLUSIONS
  Self reported LTC use was strongly associated with being diagnosed with SSD. However we could not identify a particular subgroup of users that are at increased risk to recommend targeted primary prophylaxis. The policy implications of this observation are discussed.
authors.affiliation: Psychiatry Unit, Provincial General Hospital, Ratnapura, Sri Lanka. chaturaka.rodrigo@gmail.com
authors.forename: Chaturaka
authors.initials: C
authors.lastname: Rodrigo
authors.forename: Srina
authors.initials: S
authors.lastname: Welgama
authors.forename: Alwis
authors.initials: A
authors.lastname: Gunawardana
authors.forename: Chinthaka
authors.initials: C
authors.lastname: Maithripala
authors.forename: Gamini
authors.initials: G
authors.lastname: Jayananda
authors.forename: Senaka
authors.initials: S
authors.lastname: Rajapakse
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D015331:Cohort Studies; D006801:Humans; D008297:Male; D008385:Marijuana Smoking / Q000453:epidemiology*; D001523:Mental Disorders; D008875:Middle Aged; D011050:Policy Making; D011640:Public Policy; D012189:Retrospective Studies; D013188:Sri Lanka / Q000453:epidemiology; D055815:Young Adult