© 2007 The Royal College of Psychiatrists
Correspondence |
Cognitive–behavioural therapy for avoidant personality disorder
Centre for Psychosocial Medicine, von-Siebold-Strasse 5, D-37075 Göttingen, Germany.
Centre for Psychosocial Medicine, Göttingen, Germany.
Correspondence: Email: Fleichs{at}gwdg.de
EDITED BY KIRIAKOS XENITIDIS and COLIN CAMPBELL
Emmelkamp et al (2006) reported that cognitive–behavioural therapy (CBT) was more effective than brief dynamic therapy (BDT) for the treatment of avoidant personality disorder. However, the study has several methodological shortcomings.
In the BDT group it is not clear whether and to what extent a manualised treatment was realised. The article includes non-specific references to several psychodynamic manuals and it is not clear what therapeutic procedures were actually carried out. Furthermore, no disorder-specific treatment manual was used. In contrast, in the CBT group the manual of Beck & Freeman (1990) for avoidant personality disorder was applied. No data with regard to adherence and competence were reported and thus it is not clear whether both treatments were carried out with equal competence.
Besides the presence or absence of the diagnosis according to the Structural Clinical Interview for DSM–IV Axis II Disorders (SCID–II) several self-report measures were applied as ‘primary outcome measures’. However, the authors focus on a specific measure that they regarded as primary. In addition to other outcome measures, Emmelkamp et al used the Personality Disorder Belief Questionnaire (PDBQ; Arntz et al, 2004). Arntz et al (2004) explicitly included items from Beck & Freeman (1990) and hence the PDBQ is specifically tailored to the effects of CBT. Possibly the most convincing difference between CBT and BDT was found with regard to the number of patients still fulfilling the SCID–II criteria at follow-up (9 v. 36%). However, it is not clear whether the ‘independent assessor’ was masked to the treatment group.
In two outcome measures that refer more specifically to the features of
avoidant personality disorder, the Social Phobia Anxiety Inventory (SPAI) and
the Avoidance Scale, another measure developed by the authors
(Emmelkamp, 1982), both CBT and
BDT achieved large and nearly identical pre-/post-treatment effect sizes: 0.92
v. 0.82 (SPAI) and 1.88 v. 1.75 (Avoidance Scale). Emmelkamp
et al reported that ‘CBT was significantly superior on all
primary outcome measures.’ However, for the difference between the CBT
and BDT groups in SPAI score the P was 0.09, which is not significant
at the level of 
=0.01 set by the authors. Furthermore, at follow-up,
there were no differences between CBT and BDT groups in SPAI and Avoidance
Scale scores. Differences were only reported for the PDBQ and for two scales
that refer to other personality disorders. For BDT, ‘no significant
difference was found between BDT and control’ but no data are reported.
Compared with the waiting list control, CBT was only superior in two of six
measures but the sample size of the waiting list control was small
(n=15 v. 26 for CBT and 28 for BDT post-treatment). The fact
that almost no differences were found between the waiting-list control and
both BDT and CBT is (at least in part) a result of the insufficient sample
size. Furthermore, at least in some measures, the waiting-list group achieved
medium or even large effect sizes.
The results reported by Emmelkamp et al (2006) are at variance with those reported by Svartberg et al (2004), who found BDT and CBT to be equally effective for cluster C personality disorders.
Overall, the design, statistical analyses and reporting of the results raise serious concerns about an investigator allegiance effect (Luborsky et al, 1999).
REFERENCES
- Arntz, A., Dreessen, L., Schouten, E., et al (2004) Beliefs in personality disorders: a test with the personality disorder belief questionnaire. Behavior Research and Therapy, 42, 1215 –1225.[CrossRef][Medline]
- Beck, A. R. & Freeman, A. (1990) Cognitive Therapy for Personality Disorders. Guilford.
- Emmelkamp, P. (1982) Phobic and Obsessive–Compulsive Disorders: Theory, Research and Practice. Plenum.
- Emmelkamp, P. M. G., Benner, A., Kuipers, A., et al
(2006) Comparison of brief dynamic and
cognitive–behavioural therapies in avoidant personality disorder.
British Journal of Psychiatry,
189, 60
–64.
[Abstract/Free Full Text] - Luborsky, L., Diguer, L., Seligman, D. A., et al (1999) The researcher’s own allegiances: ‘wild’ card in comparison of treatment efficacy. Clinical Psychology: Science and Practice, 6, 95 –106.
- Svartberg, M., Stiles, T. & Seltzer, M. H.
(2004) Randomized, controlled trial of the effectiveness of
short-term dynamic psychotherapy and cognitive therapy for Cluster C
personality disorders. American Journal of Psychiatry,
161, 810
–817.
[Abstract/Free Full Text]
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