Cognitive behavioural treatment for anger in adults with intellectual disabilities: a systematic review and meta-analysis

Authors:
NICOLL Matthew, BEAIL Nigel, SAXON David
Journal article citation:
Journal of Applied Research in Intellectual Disabilities, 26(1), 2013, pp.47-62.
Publisher:
Wiley

An evidence base for the use of cognitive behavioural treatment (CBT) for adults with intellectual disabilities is emerging. The aim of this paper is to systematically review the current literature on the effectiveness of CBT for anger in adults with intellectual disabilities and provide a meta-analysis of the findings. A literature search found 12 studies published since 1999 eligible for the quality appraisal (10 conducted in the UK and 2 conducted in Australia). Nine of these provided sufficient data to be included in the meta-analysis. The results from the review reveal an emerging evidence base for cognitive behavioural anger interventions in adults with intellectual disabilities. The quality appraisal revealed that studies are now utilising reliable and valid measurements of the anger construct. Furthermore, the quality appraisal revealed a good level of methodological rigour, especially in the studies that were entered into the meta-analysis. The meta-analysis revealed large uncontrolled effect sizes for the treatment of anger in adults with intellectual disabilities, but is viewed with caution due to low sample sizes. Overall, the literature is limited by concatenated data, a lack of comparative control groups and small study samples.

Extended abstract:
Author

NICOLL Matthew; BEAIL Nigel; SAXON David;

Title

Cognitive behavioural treatment for anger in adults with intellectual disabilities: a systematic review and meta-analysis.

Journal citation/publication details

Journal of Applied Research in Intellectual Disabilities, 26(1), January 2013, pp.47-62.

Summary

This systematic review examines the quality of the studies selected as well as the effects of cognitive behavioural therapy on anger. Only 12 studies, most of them from the UK, were included. Nine studies were used in the meta-analysis. The review indicates that study quality has improved since a previous review in 1999, especially in terms of the validity of the tools used to measure anger. Meta-analysis revealed a positive effect on anger in people with intellectual disabilities but the evidence is limited by the use of uncontrolled effect sizes, the small number of participants, and the use of concatenated data.

Context

Anger-control problems are common amongst people with intellectual disabilities and often lead to aggression. Cognitive behavioural therapy has been used successfully in the general population for the treatment of anger and interest within the field of intellectual disabilities is growing rapidly as the evidence base continues to expand. The aim was to examine the emerging literature as a previous systematic review reported that the evidence prior to 1999 was weak.

Methods

What sources were searched?
The electronic databases PsycArticles, Medline, and PsycINFO were searched from 1999 to 2011.

What search terms/strategies were used?
Four separate searches were conducted in which the keywords ‘developmental disability’, ‘learning disability’, ‘mental retardation’ and ‘intellectual disability’ were each combined with the term ‘anger’. Searches were limited to the title.

What criteria were used to decide on which studies to include?
Studies of the treatment of anger within a cognitive behavioural framework in adults with intellectual disabilities, and published in English in peer-reviewed journals, were eligible for inclusion. Studies could be either randomised or non-randomised controlled trials, or case series designs. The dependent variable, anger, had to be measured by qualified staff and outcomes for male and female participants had to be reported separately.  

Who decided on their relevance and quality?
The screening process is not reported in any detail. Methodological quality of the selected studies was assessed using the checklist developed by Cahill (2010) which is adapted to allow for a wide range of methodological designs. The overall quality score, maximum 32, is based on four separate subscales. Studies were rated by the first author. A random sample of four studies was independently rated by a graduate  psychologist; the Kappa rating indicated good agreement.

How many studies were included and where were they from?
The four searches yielded a total of 174 studies, 154 of which were excluded. As some of the remaining 20 studies were found to be linked duplicate studies were removed. Twelve studies were finally selected for review. There were ten studies conducted in the UK and two from Australia.

How were the study findings combined?
Data was extracted from the individual studies and effect sizes were calculated where possible. The data was subjected to quality appraisal which is reported as a narrative synthesis, and meta-analysis of effect sizes. Pre- and post-treatment data was compared and uncontrolled effect sizes were calculated; the decision to use uncontrolled effect sizes was based on a number of reasons including the aim of broadening the number of studies included in the meta-analysis. Meta-analysis was conducted using Stata software and a fixed-effects model.

Findings of the review

Quality assessment of the 12 studies revealed high levels of reporting and high levels of internal reliability, indicating an improvement in the integrity of the instruments being used to measure anger compared to the findings of previous reviews. The proportion of quality criteria addressed overall was 74.6%. The overall quality rating for the nine studies reporting sufficient data to be included in the meta-analysis was 84.5%. Lower overall scores were reported for internal reliability sampling, and external validity.

Six of the nine studies included in the meta-analysis were of group-based treatment while three focused on individualised treatment. Meta-analysis revealed an overall uncontrolled effect size of 0.88; the mean effect size was 0.84 for the group studies and 1.01 for the individual studies. However the wide 95% confidence intervals, due to the small sample sizes, indicate that the positive treatment effect is not significant.

Authors' conclusions

‘The results from the review reveal an emerging evidence base for cognitive behavioural anger interventions in adults with intellectual disabilities. The quality appraisal revealed that studies are now utilising reliable and valid measures of the anger construct...’ The meta-analysis revealed large effect sizes but the results should be viewed with caution.

Implications for policy or practice

None are discussed.

Subject terms:
learning disabilities, aggression, cognitive behavioural therapy;
Content type:
systematic review
Link:
Journal home page
ISSN online:
1468-3148
ISSN print:
1360-2322

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