Introduction: Data about the prevalence of borderline personality (BPD) and bipolar (BD) disorders comorbidity are scarce and the boundaries remain controversial. We conducted a systematic review and meta-analysis investigating the prevalence of BPD in BD and BD in people with BPD.
Methods: Two independent authors searched MEDLINE, Embase, PsycINFO and the Cochrane Library from inception till November 4, 2015. Articles reporting the prevalence of BPD and BD were included. A random effects meta-analysis and meta-regression were conducted.
Results: Overall, 42 papers were included: 28 considering BPD in BD and 14 considering BD in BPD. The trim and fill adjusted analysis demonstrated the prevalence of BPD among 5273 people with BD (39.94 ± 11.78 years, 44% males) was 21.6% (95% CI 17.0-27.1). Higher comorbid BPD in BD were noted in BD II participants (37.7%, 95% CI 21.9-56.6, studies=6) and North American studies (26.2%, 95% CI 18.7-35.3, studies=11). Meta regression established that a higher percentage of males and higher mean age significantly (p<0.05) predicted a lower prevalence of comorbid BPD in BD participants. The trim and fill adjusted prevalence of BD among 1814 people with BPD (32.22 ± 7.35 years, 21.5% male) was 18.5% (95% CI 12.7-26.1).
Limitations: Paucity of longitudinal/control group studies and accurate treatment records.
Conclusions: BPD-BD comorbidity is common, with approximately one in five people experiencing a comorbid diagnosis. Based on current diagnostic constructs, and a critical interpretation of results, both qualitative and quantitative syntheses of the evidence prompt out the relevance of differences rather similarities between BD and BPD.
Keywords: Bipolar disorder (BD); Borderline personality disorder (BPD); Comorbidity; Meta-analysis; Predictors; Prevalence; Systematic review.
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