Review: A Meta-Analysis of Psychotherapy in Cluster C Personality Disorders


The paper reviewed here is ‘Follow-up psychotherapy outcome of patients with dependent, avoidant and obsessive-compulsive personality disorders: A meta-analytic review’ by Witold Simon. The title summarises the broad aim of the study and in the abstract, the authors conclude that

The study indicates that therapy gains are usually maintained at follow-up for Cluster C clients treated with cognitive-behavio(u)ral and psychodynamic approaches as well as social skills training

Just to recap, the DSM-IV cluster C personalities refer to the anxious avoidant personality disorder (AVPD), the dependent personality disorder (DPD) and the Obsessive-Compulsive Personality Disorder (OCPD).  In the objectives section, the authors clearly outline the questions they aim to answer including the efficacy of therapy on specific and general outcome measures, efficacy of follow-up, relative therapy responsiveness of individual personality disorder subtypes and relative efficacy of therapy types. The methodology is clearly outlined incuding databases used, search terms within the databases and inclusion criteria for papers. The researchers have used detailed criteria for describing the papers and students were trained to use these criteria with the papers. The criteria scored highly on inter-rater reliability. The authors identified 15 studies between 1982 and 2006. The authors commented on the heterogeneity of treatment approaches as well as in a number of other variables. For each of the four questions they posed, the authors described the number of randomised controlled trials and non-randomised studies. In the results section they state that all of the treatments except brief dynamic therapy were effective in showing ‘improvements’ by the end of therapy compared to controls and referred to Table IV. However on inspection of Table IV, I noted that effect sizes were given but I wasn’t clear about which outcome measures the effect sizes related to. In the section on follow-up therapy the results are discussed for 3 and 6-month follow-ups and given the range of therapies examined the significant findings cover many therapies in individual trials. I couldn’t identify a statistical pooling of study results in the table or the section on follow-up studies. Indeed on closer examination, I could find no reference to effect sizes in the tables or to outcome measures nor any other indication of the effects of treatment. In the text, again I could find no reference to these measures and instead there are general remarks about individual studies or small groups of studies. In the section on differential effects according to diagnosis, the authors report that these results are ‘inconsistent’ and describe these qualitatively without any obvious reference to a pooled-analysis which might at least offer a statistical answer. A little later in the conclusions, the authors refer again to the effect sizes and here they pool the data for effect sizes using Cohen’s Classification. The effect size they explain refers to the percentage of people getting better with therapy. However it is not clear what ‘getting better’ means as improvement might be considered differently in each study and would make comparisons difficult. I didn’t see any other quantitative results given in the discussion.

In summary, perhaps the most convincing evidence was provided for the follow-up data, and here the authors have included the pooled effect sizes although there still remains the question of what exactly is meant here by ‘an improvement’. There is also the question of how diagnoses have been established in each study. For instance there has been a suggestion that anxious avoidant personality disorder has an overlap with social phobia e.g.  (Tillfors and Ekselius, 2009). If this is the case it would be interesting to see how social phobia has been excluded in these studies although the authors have referred to the heterogeneity of methodologies in the studies. The lacks of explicitly stated pooled effect-sizes in other sections of the paper make this difficult to interpret and one obvious comment is that a meta-analysis should be repeated as more study results become available although this can be said for all meta-analyses.


Tillfors M and Ekselius L. Social phobia and avoidant personality disorder: are they separate diagnostic entities or do they reflect a spectrum of social anxiety? Isr J Psychiatry Related Sci. 46(1). 25-33.

Witold Simon. Follow-up psychotherapy outcome of patients with dependent, avoidant and obsessive-compulsive personality disorders: A meta-analytic review. International Journal of Psychiatry in Clinical Practice. 2009. 13(2). 153-165.


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