From the identified articles we

From the identified articles, we were unable to demonstrate the total comorbidity between bipolar disorder and all anxiety disorders confidently, as some of the individual studies examined only one or two subtypes of the anxiety disorders, e.g. GAD or OCD. However, in twenty-nine out of fifty-two articles which including 3064 individuals, we were able to extract the total lifetime comorbidity with anxiety disorders (Fig. 2). Meta-analysis pooled prevalence of lifetime comorbidity of any anxiety disorders in bipolar disorder was 42.7% (95% CI 37.5–48.0) with high heterogeneity (Table 1). It should be noted that a higher prevalence rate of comorbid anxiety disorders is mainly due to the fact that some individuals have had multiple identified anxiety disorder conditions.

Discussion
To the best of our knowledge, there has been no previous meta-analysis examining the lifetime prevalence of comorbidity between bipolar disorder and anxiety disorders. As expected, a large amount of variation in prevalence across studies was found by graphical representation of estimates and by indices of heterogeneity. Despite this wide variation, pooled estimates are often useful to indicate the clinical burden of the comorbidities. All original studies were carried out according to interview-based methods of defining bipolar disorder and anxiety disorders, using comprehensive and fully structured tools, such as CIDI and SCID-IV and were conducted by trained interviewers. In total, we were able to identify 52 studies consisting of 13,656 individuals with bipolar affective disorder, for whom the lifetime comorbid anxiety disorders had been examined (Table 2). Meta-analysis pooled prevalence of the lifetime comorbidity of any anxiety disorders in 29 out of 52 studies was 42.7% (95% CI 37.5–48.0). However, it Dig-11-utp Supplier is to be noted that the total number of individuals with comorbid anxiety disorders was less than the above number, as some individuals had more than one identified anxiety disorder comorbidity. To examine the impact of single versus multiple anxiety disorder comorbidities, Boylan et al. (2004) found no significant differences between the groups of patients with 1, 2, 3 or more anxiety disorders for any of the outcome measures (all P values>0.15).
Whenever possible, we only used the data for bipolar type I, as some studies such as the Bridge Study (Angst et al., 2013) found higher prevalence of lifetime comorbidity in type II (27.5% vs. 16.9%). Otherwise we only included the data when the authors clearly reported no significant differences in their findings between types I and II.
Some of primary studies (Boylan et al., 2004; Angst et al., 2013; Grabski et al., 2008) found GAD to be the most common comorbid anxiety disorder in bipolar disorder. However the majority of studies found panic disorder as the most common comorbid anxiety disorder in bipolar disorder (Okan Ibiloglu and Caykoylu, 2011; Shoaib and Dilsaver, 1995). Wittchen et al. (1994) reported strong lifetime comorbidity between GAD and affective disorder (mania 10.5%, major depression 62.4% and dysthymia 39.5%).
With regard to the effects of single vs. multiple comorbid anxiety disorders, in a medulla sample of 153 bipolar I inpatient cases, Ghoreishizadeh et al. (2009) identified 43% rate of anxiety disorders with no significant relationship between anxiety disorders and the severity of bipolar disorder and the duration of hospitalisation. Their findings were consistent with the results of a study by Henry et al. (2003), but contrary to the results of some other studies (El-Mallakh and Hollifield, 2008; Sharma et al., 1995; Masi et al., 2007; Dilsaver and Chen, 2003; Dineen Wagner, 2006). Using a random effect meta-analysis in our pooled data, we found panic disorder to be the most common comorbid anxiety disorder in bipolar disorder: 16.8% (95% CI 13.7–20.1), followed by GAD and social anxiety disorder with a prevalence of 14.4% (95% CI 10.8–18.3) and 13.3% (95% CI 10.1–16.9), respectively. We also estimated the rate of lifetime comorbidity between bipolar disorder and PTSD, specific phobia, OCD and agoraphobia to be 10.8% (95% CI 7.3–14.9), 10.8% (95% CI 8.2–13.7), 10.7% (95% CI 8.7–13.) and 7.8% (95% CI 5.2–11.0), respectively.