title: Bipolar disorder prevalence: a systematic review and meta-analysis of the literature.
abstract: OBJECTIVE
  Bipolar disorder (BD) is common in clinical psychiatric practice, and several studies have estimated its prevalence to range from 0.5 to 5% in community-based samples. However, no systematic review and meta-analysis of the prevalence of BD type 1 and type 2 has been published in the literature. We carried out a systematic review and meta-analysis of the lifetime and 1-year prevalence of BD type 1 and type 2 and assessed whether the prevalence of BD changed according to the diagnostic criteria adopted (DSM-III, DSM-III-R vs. DSM-IV).
  
  
  METHODS
  We searched MEDLINE, Scopus, Web of Science, PsycINFO, and the reference lists of identified studies. The analyses included 25 population- or community-based studies and 276,221 participants.
  
  
  RESULTS
  The pooled lifetime prevalence of BD type 1 was 1.06% (95% confidence interval [95%CI] 0.81-1.31) and that of BD type 2 was 1.57% (95%CI 1.15-1.99). The pooled 1-year prevalence was 0.71% (95%CI 0.56-0.86) for BD type 1 and 0.50% (95%CI 0.35-0.64) for BD type 2. Subgroup analysis showed a significantly higher lifetime prevalence of BD type 1 according to the DSM-IV criteria compared to the DSM-III and DSM-IIIR criteria (p < 0.001).
  
  
  CONCLUSIONS
  This meta-analysis confirms that estimates of BD type 1 and type 2 prevalence are low in the general population. The increase in prevalence from DSM-III and DSM-III-R to DSM-IV may reflect different factors, such as minor changes in diagnostic operationalization, use of different assessment instruments, or even a genuine increase in the prevalence of BD.
authors.affiliation: Fundação Oswaldo Cruz, Belo Horizonte, MG, Brazil.
authors.forename: Adauto S
authors.initials: AS
authors.lastname: Clemente
authors.affiliation: Department of Mental Health, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
authors.forename: Breno S
authors.initials: BS
authors.lastname: Diniz
authors.affiliation: Department of Mental Health, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Nicolato
authors.affiliation: Molecular Psychiatry Laboratory, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: Flavio P
authors.initials: FP
authors.lastname: Kapczinski
authors.affiliation: Center of Excellence on Mood Disorders, Department of Psychiatry and Behavioral Sciences, Texas Health and Science University, Houston, TX, USA.
authors.forename: Jair C
authors.initials: JC
authors.lastname: Soares
authors.affiliation: Fundação Oswaldo Cruz, Belo Horizonte, MG, Brazil.
authors.forename: Josélia O
authors.initials: JO
authors.lastname: Firmo
authors.affiliation: Fundação Oswaldo Cruz, Belo Horizonte, MG, Brazil.
authors.forename: Érico
authors.initials: É
authors.lastname: Castro-Costa
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001714:Bipolar Disorder / Q000175:diagnosis* / Q000453:epidemiology*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D006801:Humans; D008875:Middle Aged; D015995:Prevalence