title: Meta-analysis of epidemiologic studies of pediatric bipolar disorder.
abstract: OBJECTIVE
  Meta-analyze all published epidemiologic studies reporting pediatric mania or bipolar disorder to investigate whether pediatric bipolar disorder is becoming more prevalent and whether rates vary significantly by country.
  
  
  METHODS
  Searches of PubMed and PsycInfo were conducted through the spring of 2010 using the following search terms: child, pediatric, young, adolescent, epidemiology, prevalence, bipolar, mania, suicide, and psychiatric. We also manually reviewed references in recent reviews of epidemiology of bipolar disorder.
  
  
  METHODS
  All studies reporting rates for mania or hypomania in community epidemiologic samples with participants up to 21 years of age.
  
  
  METHODS
  All articles were coded to extract relevant variables. Prevalence rates were calculated from reported number of cases with bipolar disorders, then logit transformed. Twelve studies were included, enrolling 16,222 youths between the ages of 7 and 21 years during a period from 1985 to 2007. Six samples were from the United States; 6 were from other countries (the Netherlands, the United Kingdom, Spain, Mexico, Ireland, and New Zealand).
  
  
  RESULTS
  The overall rate of bipolar disorder was 1.8% (95% CI, 1.1%-3.0%). There was no significant difference in the mean rates between US and non-US studies, but the US studies had a wider range of rates. The highest estimates came from studies that used broad definitions and included bipolar disorder not otherwise specified. Year of enrollment was negatively correlated with prevalence (r = -0.04) and remained nonsignificant when controlling for study methodological differences.
  
  
  CONCLUSIONS
  Mean rates of bipolar disorder were higher than commonly acknowledged and not significantly different in US compared to non-US samples, nor was there evidence of an increase in rates of bipolar disorder in the community over time. Differences in diagnostic criteria were a main driver of different rates across studies.
authors.affiliation: Department of Psychology and Psychiatry, University of North Carolina at Chapel Hill, NC 27599-3270, USA.
authors.forename: Anna R
authors.initials: AR
authors.lastname: Van Meter
authors.forename: Ana Lúcia R
authors.initials: AL
authors.lastname: Moreira
authors.forename: Eric A
authors.initials: EA
authors.lastname: Youngstrom
mesh_terms: D000293:Adolescent; D001714:Bipolar Disorder / Q000453:epidemiology*; D002648:Child; D006801:Humans; D007494:Ireland / Q000453:epidemiology; D008800:Mexico / Q000453:epidemiology; D009426:Netherlands / Q000453:epidemiology; D009520:New Zealand / Q000453:epidemiology; D015995:Prevalence; D013030:Spain / Q000453:epidemiology; D006113:United Kingdom / Q000453:epidemiology; D014481:United States / Q000453:epidemiology; D055815:Young Adult