A SYSTEMATIC REVIEW OF THE EFFECTS OF PSYCHOTHERAPY ...

published in peer-reviewed journals or disseminated through theses and dissertations databases and
published white papers. Some articles not in English could not be obtained or translated, such as
proceedings from international conferences held in countries outside the United States; e.g.
Congresses of the Federation of Riding for the Disabled. Consequently, most articles not in English
were excluded except those that could be translated using computer translation software. Articles
pertaining to physical disabilities were excluded from this review. From this preliminary search, forty
articles were retrieved for consideration for inclusion in this systematic review; Reports which could not
be read in full were excluded. Papers that were published in professional membership journals were
excluded because of the possibility of lack of objective peer review resulting in publication bias.
Anecdotal reports and case studies were excluded in an effort to isolate the quantitative research that
has been done to date in an attempt to begin to fill the gap in the literature. In a narrowing of focus,
and because several of the studies have been discussed elsewhere, it was determined to include only
studies published since 2000 that quantified the benefits of psychotherapy involving equines across
age groups. Qualitative studies were excluded. Five studies could not be retrieved in full for review
(Appendix A). See Figure 2.1 for a summary of the retrieval process.
2.1.3 Data Extraction
Fourteen studies that met inclusion criteria were extracted from the literature. All of the studies
that met inclusion criteria were observational in nature, quasi-experimental or descriptive pre-post
designs, with one experimental study of efficacy, and were evaluated using Grading of
Recommendations, Assessment, Development, Evaluation (GRADE) criteria developed by the
GRADE working group in association with the World Health Organization (WHO) (Table 2.1) (Oxman,
Schünemann, & Fretheim 2006), adapted for use in this review. Population, Intervention,
Comparison, and Outcome (PICO) criteria, as recommended by Gambrill (2006), were applied to all
studies. The answers to PICO questions define the population under study, the specified intervention,
the comparison or lack thereof, and desired outcomes, all with an element of time; e.g. how old are the
participants? How long is the treatment protocol? When is the outcome measured? Finally, evidencebased
and –informed practice levels of evidence were considered during the data synthesis phase of
this review, as recommended by Bandolier, Gambrill and the Centre for Evidence-based medicine.
19