Prevalence of fibromyalgia and co-morbid bipolar disorder: A systematic review and meta-analysis

Fibromyalgia (FM) is a chronic disorder with high morbidity and significant health service utilization costs. Few studies have reported on the phenotypic overlap of FM and bipolar disorder (BD). The aim of this review is to qualitatively and quantitatively summarize the results and clinical implications of the extant literature on the co-occurrence of FM and BD.

A systematic search of PubMed/Medline, Cochrane, PsycINFO, CINAHL and Embase was conducted to search for relevant articles. Articles were included if incidence and/or prevalence of BD was determined in the FM sample. Results of prevalence were pooled from all studies. Pooled odds ratio (OR) was calculated based on case-control studies using standard meta-analytic methods.

A total of nine studies were included. The pooled rate of BD comorbidity in samples of FM patients was 21% (n=678); however, results varied greatly as a function of study methodology. Case-controlled studies revealed a pooled OR of 7.55 of BD co-morbidity in samples of FM patients [95% Confidence Interval (CI)=3.9-14.62, FM n=268, controls n=413] with low heterogeneity (I(2)=0%).

The current study was limited by the low number of available studies and heterogeneity of study methods and results.

These data strongly suggest an association between BD and FM. Future studies employing a validated diagnostic screen are needed in order to more accurately determine the prevalence of BD in FM. An adequate psychiatric assessment is recommended in FM patients with suspected symptoms consistent with BD prior to administration of antidepressants in the treatment of FM.