A comprehensive meta-analysis to identify the proportions of comorbid personality disorders (PD) across the major subtypes of anxiety disorders (AD) has not previously been published.

A literature search identified 125 empirical papers from the period 1980–2010 on patients with panic disorders, social phobia, generalised anxiety, obsessive-compulsive (OCD) and post-traumatic stress disorder (PTSD). Several moderators were coded.

The rate of any comorbid PD was high across all ADs, ranging from .35 for PTSD to .52 for OCD. Cluster C PDs occurred more than twice as often as cluster A or B PDs. Within cluster C the avoidant PD occurred most frequently, followed by the obsessive-compulsive and the dependent PD. PTSD showed the most heterogeneous clinical picture and social phobia was highly comorbid with avoidant PD. A range of moderators were examined, but most were non-significant or of small effects, except an early age of onset, which in social phobia increased the risk of an avoidant PD considerably. Gender or duration of an AD was not related to variation in PD comorbidity.

Blind rating of diagnoses was recorded from the papers as an indication of diagnostic validity. However, as too few studies reported it the validity of the comorbid estimates of PD was less strong.

The findings provided support to several of the proposed changes in the forthcoming DSM-5. Further comorbidity studies are needed in view of the substantial changes in how PDs will be diagnosed in the DSM-5.