The prevalence and predictors of bipolar and borderline personality disorders comorbidity: Systematic review and meta-analysis

- Borderline Personality Disoder (BPD) is common in bipolar disorder (BD), especially in Type-BD (BD-II). The opposite trend is also true.
- Overall, up to 21.6% of BD samples have comorbid BPD. Also, BDP comorbidity rates were highest among BD-II participants (37.7%) recruited in North American studies (26.2%).
- A higher percentage of males and higher mean age significantly (p<0.05) predicted a lower prevalence of comorbid BPD in BD.
- The adjusted prevalence of BD among people with BPD was 18.5%.
- BPD-BD comorbidity is common, with approximately one in five people experiencing a comorbid diagnosis. Both the diagnostic and clinical implications of the matter have been discussed in the text..

IntroductionData 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.MethodsTwo 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.ResultsOverall, 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).LimitationsPaucity of longitudinal/control group studies and accurate treatment records.ConclusionsBPD-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.