Self-help treatment of anxiety disorders: a meta-analysis and meta-regression of effects and potential moderators

CRD summary

This review concluded that self-help treatment was effective for the treatment of anxiety disorders, and should be provided as part of stepped care treatment models in community services. In view of the uncertain quality of the evidence base and limitations of the review process, a degree of caution might be required to interpret these conclusions.

Authors' objectives

To assess the effectiveness of self-help treatment for anxiety disorders and identify potential moderating factors that influence the effect of self-help treatment.

Searching

PubMed, Web of Knowledge, PsycINFO and Cochrane Central Register of Controlled Trials (CENTRAL) were searched. Search dates were not reported. Search terms were reported in an appendix. Reference lists of relevant publications were handsearched.

Study selection

Randomised controlled trials (RCTs) that compared self-help treatment with a control in adults (≥18 years) with anxiety disorders were eligible for inclusion. Eligible studies had to report effect sizes or relevant data to calculate them. Self-help treatment could be delivered on paper format (book, pamphlet) or distributed as computer software or through the Internet. Only studies where therapist contact was secondary to self-help treatment were eligible for inclusion. The primary outcome of interest was change in specific anxiety symptoms. Secondary outcomes were changes in other symptoms (general anxiety, depression) and quality of life.

All the included studies investigated self-help treatment based on cognitive and/or behavioral therapy models. The included patients had primary anxiety disorders that included panic disorder/agoraphobia, social phobia, post-traumatic stress disorder/acute stress disorder, mixed anxiety/depression, specific phobia, generalised anxiety disorder, obsessive-compulsive disorder and mixed anxiety disorders. Controls in the included studies were placebo, waiting list and face-to-face treatment. The mean age of included patients was 36.6 years (range 22.2 to 47.1). Most of the included patients were female. Where reported, follow-up ranged from 1.5 to 36 months.

One reviewer assessed abstracts for inclusion, seven of which were checked by a second reviewer. The authors did not state how many reviewers assessed studies for inclusion of full papers.

Assessment of study quality

Study quality was assessed using criteria for attrition rate and intention-to-treatment analysis.

The authors did not state how many reviewers performed quality assessment.

Data extraction

Data were extracted to enable calculation of standardised mean differences (Hedges' g) and 95% confidence intervals (CI). It appeared that one reviewer performed data extraction.

Methods of synthesis

The included studies were combined in a meta-analysis. Pooled standardised mean differences (Hedges' g) with 95% CI were calculated using a random-effects model. Statistical heterogeneity was assessed using the Q and Ι² statistics. Subgroup analyses were based on different analysis methods (intention-to-treat analysis versus complete analysis), different settings (community samples versus clinical samples) and different treatment formats (paper versus computer software/internet). Meta-regression analyses were used to investigate the relationship between the effect size and potential factors. Publication bias was assessed using funnel plots, Egger's test, Begg and Mazumdar test and calculation of fail safe numbers.

Results of the review

Fifty-six studies were included in the review (4,713 participants). The average attrition rate was 16.5% (range zero to 54.8%). Thirty studies used an intention-to-treat analysis.

Compared with waiting list or placebo, self-help treatment was associated with a moderate to large effect size (g=0.78, 95% CI 0.67 to 0.90; 54 studies) for reduction of anxiety symptoms. Self-help treatment compared with face-to-face treatment showed a small effect that favoured face-to-face treatment (g=−0.20, 95% CI -0.37 to -0.02; 28 studies). Significant heterogeneity was found for both outcomes (Ι²=48.32% and Ι²=66.85%).

When self-help treatment was compared to waiting list or placebo, subgroup analyses showed that self-help treatment format, different primary anxiety diagnosis and recruitment settings were significantly associated with treatment outcome in bivariate analyses. There was no significant relationship between treatment outcome and use of intention-to-treat analysis. Only the variable of recruitment settings remained significant in a meta-regression analysis.

The meta-regression analysis also indicated that type of control groups, treatment format and patient gender were significantly associated with treatment outcome when self-help treatment was compared to face-to-face treatment.

There was potential for publication bias. Results of other outcomes were reported.

Authors' conclusions

Self-help treatment was effective for treatment of anxiety disorders and should be provided as part of stepped care treatment models in community services.

CRD commentary

This review addressed a clear research question and was supported by appropriate inclusion criteria. Several relevant databases were searched. Efforts were made to find published studies but not unpublished studies, which increased potential for publication bias. Publication bias was assessed and the results indicated that there was possible publication bias. It was unclear whether language restrictions were used in the search, which made it difficult to assess language bias. It appeared that most of study selection process was not performed in duplicate; it was unclear whether sufficient attempts were made to minimise reviewer errors and biases during data extraction and quality assessment. Although some aspects of study quality were discussed, only very limited criteria were used to assess study quality; some important criteria for randomised controlled trials such as randomisation and allocation concealment were not assessed. Statistical heterogeneity was assessed and appropriate methods were used to pool the results. Heterogeneity was further investigated based on a range of factors that included treatment format, primary anxiety diagnosis and recruitment settings.

Given the uncertain quality of the evidence base and limitations of the review process, a degree of caution might be required to interpret the authors' conclusions.

Implications of the review for practice and research

Practice: The authors stated that self-help treatment should be made available as a standard treatment provided to patients who seek help in public health care services.

Research: The authors stated that future research should address issues of the effectiveness of self-help treatment in clinical care. Future studies should identify factors to maximise treatment effects and overcome potential barriers for implementing self-help treatment in clinical care settings. There was a need for further studies targeting older patients to investigate the feasibility of self-help treatment in this age group.

Funding

Western Norway Regional Health Authority.

Bibliographic details

Haug T, Nordgreen T, Ost LG, Havik OE. Self-help treatment of anxiety disorders: a meta-analysis and meta-regression of effects and potential moderators. Clinical Psychology Review 2012; 32(5): 425-445. [PubMed: 22681915]

Original Paper URL

http://www.sciencedirect.com/science/article/pii/S0272735812000487

Indexing Status

Subject indexing assigned by NLM

MeSH

Anxiety Disorders /psychology /therapy; Bibliotherapy; Cognitive Therapy /methods; Humans; Self Care /methods; Therapy, Computer-Assisted; Treatment Outcome

AccessionNumber

12012029903

Database entry date

12/04/2013

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.