Objective: To estimate the lifetime prevalence of 12 DSM-IV disorders with psychotic symptoms in a general population survey.
Method: Addresses were contacted in a multistage clustered area probability sampling frame of administrative neighbourhoods and households, covering 9 districts and 302 neighbourhoods in the Izmir metropolitan area between November 2007 and October 2008. One household member aged between 15 and 64 years and available to complete the interview was randomly selected using a within-household sampling method. The primary screening instrument was the Composite International Diagnostic Interview 2.1. A systematic screening procedure was implemented to detect probable cases with any psychotic disorder. Those selected by the screens were re-interviewed with the Structured Clinical Interview for DSM-IV. Diagnoses of individuals who were not available for re-interview were made by combining screening information with case register diagnoses and/or the telephone interviews with relatives or spouse.
Results: A total of 4011 individuals were screened for disorders with psychotic symptoms. After screening, 499 respondents were selected as a probable case. 277 of screen positive respondents were available for clinical reappraisal. Initial screening interviews and additional material were used for best estimate diagnoses of the remaining 172 respondents. Total lifetime prevalence of 12 DSM-IV disorders with psychotic symptoms was 2.62%. Lifetime prevalence of each disorder separately were as follows: 0.74% for schizophrenia, 0.20% for schizoaffective disorder, 0.05% for schizophreniform disorder, 0.10% for delusional disorder, 0.12% for brief psychotic disorder, 0.55% for major depressive disorder with psychotic features, 0.37% for bipolar I disorder, 0.20% for substance induced psychotic disorder, and 0.07% for psychotic disorders due to a general medical condition.
Conclusion: Total lifetime prevalence of disorders with psychotic symptoms is higher than any previously reported estimates in Turkey; with a prevalence of approximately 2.5%, these disorders can be considered a major public health concern.