title: Relationships between obsessive-compulsive symptomatology and severity of psychosis in schizophrenia: a systematic review and meta-analysis.
abstract: OBJECTIVE
  The presence of obsessive-compulsive symptoms (OCS) or obsessive-compulsive disorder (OCD) is common in patients with schizophrenia. The impact of OCS and OCD on severity of psychotic symptoms has been assessed in several past studies yielding inconclusive results. In this report, we aim to integrate the findings of prior studies by means of a systematic review followed by a meta-analysis.
  
  
  METHODS
  A search of studies in PubMed (from 1950 to September 2006) and PsycINFO (from 1966 to September 2006) databases was performed to assess the influence of OCS and OCD on severity of psychotic symptoms in patients with schizophrenia using as syntax ("schizophrenia" OR "psychosis" OR "psychotic") AND ("obsessive-compulsive disorder" OR "OCD" OR "obsession*" OR "compulsion*" OR "obsessiv*" OR "compulsiv*"). Reference lists of all retrieved articles were also hand-searched.
  
  
  METHODS
  Twenty-three studies were included in the systematic review, and 18 articles provided usable data for the meta-analysis.
  
  
  METHODS
  All relevant data were extracted using a standardized report form by 2 investigators. Effect sizes and pooled estimates were calculated. Data were analyzed separately for studies using an OCS or OCD definition.
  
  
  RESULTS
  The presence of OCS was significantly associated with greater severity of global psychotic symptoms (standardized mean difference [95% CI], 0.39 [0.14 to 0.64]), positive psychotic symptoms (0.28 [0.00 to 0.56]), and negative psychotic symptoms (0.36 [0.11 to 0.62]). In contrast, no differences in the severity of global psychotic symptoms (0.19 [-0.14 to 0.51]), positive psychotic symptoms (-0.01 [-0.20 to 0.19]), or negative psychotic symptoms (-0.11 [-0.30 to 0.08]) were found for the OCD versus non-OCD subgroups.
  
  
  CONCLUSIONS
  This first meta-analysis revealed that the presence of obsessive-compulsive symptoms in schizophrenia is associated with higher global, positive, and negative psychotic symptoms. This association was not found when a categorical definition of obsessive-compulsive disorder was used.
authors.affiliation: Department of Psychiatry, Mount Sinai School of Medicine, New York, NY, USA. ruthcunill@gmail.com
authors.forename: Ruth
authors.initials: R
authors.lastname: Cunill
authors.forename: Xavier
authors.initials: X
authors.lastname: Castells
authors.forename: Daphne
authors.initials: D
authors.lastname: Simeon
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015897:Comorbidity; D006801:Humans; D008875:Middle Aged; D009771:Obsessive-Compulsive Disorder / Q000175:diagnosis* / Q000453:epidemiology; D011569:Psychiatric Status Rating Scales; D012559:Schizophrenia / Q000175:diagnosis* / Q000453:epidemiology; D012565:Schizophrenic Psychology; D055815:Young Adult