An umbrella review of the evidence
Psychologists increasingly enquire about the use of animal-assisted therapies as part of psychological practice. Interventions involving animals including dogs, horses, cats and fish have increased in popularity over the past decade with a range of health professionals incorporating animals as part of their service. A recent review published in the Australian Journal of Psychology expands our understanding of the usefulness of animal-assisted therapy, specifically equine-assisted intervention, and its impact on the wellbeing of adults and children.
The umbrella review (a review of systematic reviews) by Stern and Chur-Hansen (2019) set out to investigate the impact of animal-assisted therapies on physical, psychological and social wellbeing. The investigation of equine-assisted interventions (also referred to as hippotherapy) is of particular interest to psychology as by definition this therapy must involve a mental health practitioner. This is in contrast to, for example, equine-assisted activities involving horses such as riding therapy and vaulting, which may be facilitated by non-mental health professionals.
Criteria for inclusion
The umbrella review included systematic reviews with and without meta-analyses as long as the review had a clear and comprehensive search strategy using a number of databases and demonstrated a critical appraisal of the risk of bias. Published and unpublished reviews were sourced from multiple databases and libraries. In reviewing relevant articles, both positive and negative health and wellbeing outcomes were of interest.
Reviews that met the inclusion criteria were evaluated by two independent reviewers for methodological quality based on the Joanna Briggs Institute critical appraisal instruments designed to assess the extent to which a review has taken account of bias in its design, conduct and analysis1. In addition, articles were only included if they were found to meet criteria on five questions ensuring the following features: having a clear review question, appropriate inclusion criteria, a rigorous search strategy, a process for appraisal of studies, and an acceptable practice for combining studies.
Appraisal of systematic reviews
Of the potential 644 citations that were identified, the majority were excluded due to duplication, lack of relevance or being incomplete. This led to a total of 149 articles being reviewed. Of these only 19 articles met inclusion criteria. These were assessed by two independent reviewers who found that many of the papers had methodological flaws with six reviews being excluded as they did not meet the requirements of the five features identified earlier. Subsequently, 13 reviews were included in this umbrella review, covering 128 studies which across them included 79 unique studies.
Findings
The 79 unique studies focused on both child and adult populations. The studies investigated equine-assisted interventions and hippotherapy with children with physical disabilities such as cerebral palsy as well as studies of children with autism spectrum disorder. Similarly, adult studies investigated the impact on physical presentations (e.g., spinal cord injuries, multiple sclerosis, recovery post cancer, stroke or surgery) as well as presentations of mental illness. The outcomes for studies were mixed with some studies reporting improvements on a range of outcome measures while others found no change. Nevertheless, what has been concluded by the authors is that current studies in this area are flawed with serious methodological problems making it impossible to draw conclusions that could support the use of equine-assisted interventions.
All of the review articles had limitations, particularly around risk of bias but also including small sample sizes, no control or comparison group, no randomisation and a lack of information about the actual intervention. Of concern was that despite disclosing serious limitations in their reviews, authors of at least two reviews went on to conclude positive outcomes and to argue for use of these interventions regardless of the lack of evidence to support their conclusions.
Stern and Chur-Hansen (2019) note that more rigorous research is needed to draw conclusions about the contribution of equine-assisted interventions to the wellbeing of adults and children. They also point to the limited number of studies overall given the popularity of this therapy and a lack of research into the psychological benefits in particular, with the majority of studies in this review focusing on physical health outcomes such as posture, balance and gait. A number of limitations of the umbrella review were identified including that only papers in English were included and some publication bias was noted with for example budget constraints limiting access to all potential full-text publications.
The final word
This umbrella review sought to determine the evidence for the use of equine-assisted interventions to improve physical, social and psychological wellbeing. The authors concluded that the current evidence base has significant methodological limitations to the extent that no support for the use of equine-assisted interventions can be espoused.
What remains is a need for quality research to be undertaken in this area. Only with well-designed, rigorous quantitative and qualitative studies can we determine the true impact of equine-assisted interventions on physical, social and psychological wellbeing.
doi.org/10.1111/ajpy.12246