Psychological Medicine



Review Article

Internet-based cognitive behaviour therapy for symptoms of depression and anxiety: a meta-analysis


VIOLA SPEK a1a2c1, PIM CUIJPERS a3, IVAN NYKLÍCEK a1, HELEEN RIPER a4, JULES KEYZER a2 and VICTOR POP a1a2
a1 Department of Psychology and Health, Tilburg University, The Netherlands
a2 Diagnostic Centre Eindhoven, The Netherlands
a3 Department of Clinical Psychology, Vrije Universiteit Amsterdam, The Netherlands
a4 Trimbos-instituut, Netherlands Institute of Mental Health and Addiction, The Netherlands

Article author query
spek v   [PubMed][Google Scholar] 
cuijpers p   [PubMed][Google Scholar] 
nyklicek i   [PubMed][Google Scholar] 
riper h   [PubMed][Google Scholar] 
keyzer j   [PubMed][Google Scholar] 
pop v   [PubMed][Google Scholar] 

Abstract

Background. We studied to what extent internet-based cognitive behaviour therapy (CBT) programs for symptoms of depression and anxiety are effective.

Method. A meta-analysis of 12 randomized controlled trials.

Results. The effects of internet-based CBT were compared to control conditions in 13 contrast groups with a total number of 2334 participants. A meta-analysis on treatment contrasts resulted in a moderate to large mean effect size [fixed effects analysis (FEA) d=0·40, mixed effects analysis (MEA) d=0·60] and significant heterogeneity. Therefore, two sets of post hoc subgroup analyses were carried out. Analyses on the type of symptoms revealed that interventions for symptoms of depression had a small mean effect size (FEA d=0·27, MEA d=0·32) and significant heterogeneity. Further analyses showed that one study could be regarded as an outlier. Analyses without this study showed a small mean effect size and moderate, non-significant heterogeneity. Interventions for anxiety had a large mean effect size (FEA and MEA d=0·96) and very low heterogeneity. When examining the second set of subgroups, based on therapist assistance, no significant heterogeneity was found. Interventions with therapist support (n=5) had a large mean effect size, while interventions without therapist support (n=6) had a small mean effect size (FEA d=0·24, MEA d=0·26).

Conclusions. In general, effect sizes of internet-based interventions for symptoms of anxiety were larger than effect sizes for depressive symptoms; however, this might be explained by differences in the amount of therapist support.

(Published Online November 20 2006)


Correspondence:
c1 Tilburg University, PO Box 90153, 5000 LE Tilburg, The Netherlands. (Email: v.r.m.spek@uvt.nl)


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