title: The Psychological Therapy Outcome Scale – Intellectual Disabilities (PTOS-ID): the development of a psychological therapy outcome measure for adults with intellectual disabilities
Creators: name: Vlissides, Nikolaos
Publisher: name: University of Liverpool Repository
Year: 2015

description: People with intellectual disabilities are more likely to experience living circumstances and life events associated with an increased risk of mental health problems, compared to the general population (Hulbert-Williams &amp; Hastings, 2008). These include: lack of meaningful relationships, stigmatization, unemployment, and discrimination (Martorell et al., 2009; Thornicroft, 2006). Prevalence of mental health problems are difficult to determine within this population, with estimates ranging from 10% to 39% (Emerson &amp; Hatton, 2007). Pharmacological and behavioural approaches have often been used in the treatment of mental health problems for people with intellectual disabilities (Vereenooghe &amp; Langdon, 2013). Bender (1993) argued that the lack of psychotherapeutic interventions available was due to a perceived “therapeutic disdain” towards this population. Difficulties identifying mental health problems in people with intellectual disabilities, perceived lack of training amongst practitioners, and lack of research evidence have also been cited as reasons for lack of provision of psychotherapy services (Emerson, Moss &amp; Kiernan, 1999; Royal College of Psychiatrists, 2004; Taylor &amp; Knapp, 2013). These views have been challenged by clinicians, and there is a growing evidence base of the effectiveness of psychological therapies with people with intellectual disabilities (Willner, 2005). The research has come from both single case studies (Kellett, Beail, Bush, Dyson &amp; Wilbram, 2009; Salvadori &amp; Jackson, 2009) and controlled clinical trials (Taylor, Novaco, Gillmer, Robertson &amp; Thorne, 2005). Recent systematic reviews and meta-analyses have also highlighted the effectiveness of Cognitive Behavioural Therapy (CBT) and psychodynamic therapy with this population (James &amp; Stacey, 2014; Nicoll, Beail &amp; Saxon, 2013; Vereenooghe &amp; Langdon, 2013). In one of the most comprehensive reviews to date, Prout and Nowak-Drabik (2003) reviewed the outcome and effectiveness of 92 studies and found that there was a moderate benefit of psychotherapy for people with intellectual disabilities. Recent legislation in the United Kingdom has responded by recommending improved access to psychological therapy for people with intellectual disabilities (Department of Health (DoH), 2007; 2009). The emergence of practice-based evidence has also meant that there is a growing expectation that services that provide psychological therapies show some evidence for the effectiveness of what they do (DoH, 2010). Coupled with this is the Payment by Results (PbR) initiative, where commissioners will pay healthcare providers dependent on the number of patients seen and outcomes achieved (DoH, 2013). One of the difficulties for providers of psychological therapies for people with intellectual disabilities is the availability of valid and reliable therapy outcome measures that can be easily used in service settings and accurately assess the effectiveness of interventions (Skelly, 2011; Weston, Elsworth &amp; Stacey, 2011). Thesis This thesis aims to address the difficulties in measuring outcomes of psychological therapy with people with intellectual disabilities. The first paper will systematically review the quality of outcome measures that have been used in psychological therapies with adults with intellectual disabilities. The second paper will assess the psychometric properties of the Psychological Therapy Outcome Scale – Intellectual Disabilities (PTOS-ID), a newly developed therapy outcome measure designed specifically for use with people with intellectual disabilities. Timeline of Work Elements of research reported in this thesis were completed before the commencement of the Doctorate in Clinical Psychology programme. These were the development of the PTOS-ID, which included selection of the dependent variables through the use of focus groups; the selection of the item pool; and the development of the response format (please see the Introduction of the research paper for further details). The assessment of the psychometric properties of the PTOS-ID (i.e. construct validity, concurrent validity and internal consistency) was completed for the research study reported in this thesis in partial fulfilment of the award of Doctor of Clinical Psychology. Data were collected through service audits both prior to, and during, the period of study for this doctorate.