Updated Meta-Analysis of Epidemiologic Studies of Pediatric Bipolar Disorder

Research on pediatric bipolar disorder (PBD) has grown substantially in the past 7 years; updating a 2011 meta-analysis of PBD prevalence could improve understanding of factors that influence prevalence.

A literature review of papers published in English was updated in 2018 using PubMed and PsycINFO. Search terms included pediatric, child, "bipolar disorder," bipolar, mania, prevalence, epidemiology, community, adolescent, and youth.

Inclusion criteria were (1) youth epidemiologic sample, (2) number of youth with bipolar spectrum disorders reported, and (3) prevalence rates for youth differentiated from prevalence for those over age 21 years (if both included). Of 2,400 articles retrieved, 44 were evaluated and 8 new were included.

Prevalence rates for each bipolar subtype were recorded as reported; hypothesized moderators (eg, study characteristics, environmental factors) were also coded.

Eight additional studies resulted in a total sample of 19 studies, tripling the sample size to N = 56,103 and n = 1,383 with bipolar disorder. Seven studies were from the United States, and 12 were from South America, Central America, or Europe. Weighted average prevalence of bipolar spectrum disorders was 3.9% (95% CI, 2.6%-5.8%). There was significant heterogeneity across studies (Q = 759.82, df = 32, P < .0005). The pooled rate of bipolar I was 0.6% (95% CI, 0.3%-1.2%); these rates were also heterogeneous (Q = 154.27, df = 13, P < .0001). Predictors of higher bipolar spectrum disorder prevalence were the use of broad bipolar criteria (P < .0001), older minimum age (P = .005), and lifetime prevalence (P = .002). Newer studies were associated with lower rates (P < .0001).

The updated meta-analysis confirms that rates of bipolar spectrum disorders are not higher in the United States than in other Western countries, nor are rates increasing over time. Nonstandard diagnostic criteria result in highly variable prevalence rates, as does focusing on narrow definitions of PBD to the exclusion of the full spectrum. Consistent application of validated criteria could help to settle questions regarding PBD prevalence. Studies from non-Western countries are needed to refine understanding of international prevalence and risk factors.