Development and psychometric evaluation of the Discrimination and Stigma Scale (DISC)
Introduction
Stigma is defined as a characteristic which individuals possess (or are believed to possess) that conveys an identity which is devalued in a particular social context (Crocker et al., 1998). Mental illness is associated with devaluation in a number of social contexts including: the workplace; healthcare settings; acting as a parent; and personal relationships (King et al., 2007, Link et al., 1997, Ritsher et al., 2003, Wahl, 1999). Three elements of stigma can be considered: (1) perceived stigma or the belief that the public hold negative attitudes towards people with a mental health problem, (2) experienced stigma or reported instances of unfair treatment or discrimination due to having a mental health problem and (3) self-stigma or adopting a stigmatised view of oneself (Yanos et al., 2008). Stigma research has largely focused on the measurement of perceived stigma. A recent review of studies using survey-based measures (n=52) reported that 79% used a measure of perceived stigma, 46% a measure of experienced stigma and 33% a measure of self-stigma (Brohan et al., 2010b). This review further suggests that, although several survey measures have addressed aspects of experienced stigma, there is currently no psychometrically validated measure that was developed with a specific focus on understanding the scope and content of these experiences.
The Discrimination and Stigma Scale (DISC) was developed to address this gap. It is based on the definition of Thornicroft et al. (2007), who present stigma as an overarching term including three elements: (1) problems of knowledge (ignorance or misinformation); (2) problems of attitudes (prejudice); and (3) problems of behaviour (discrimination) (Thornicroft et al., 2007). This definition moves the stigma focus from the characteristics of the individual to the problems that perpetuate stigma. The DISC focuses on the third aspect of stigma: problems of behaviour or discrimination. It is an interview-based measure which collects qualitative and quantitative data to provide a rating of the degree to which discrimination has been experienced in various areas of life including work, relationships, parenting, housing, leisure, and religious activities. The qualitative aspect of the scale asks respondents, for each domain, to give an example of how they have been treated differently (or not) from other people because of their diagnosis of mental illness. Participants are then asked to given a Likert scale rating for each item, which is the quantitative aspect of the scale.
A preliminary version of the DISC was developed as part of the International Study on Discrimination and Stigma Outcomes (INDIGO) (Thornicroft et al., 2009). In scale development, face and content validity were established through a literature review, Delphi consultation and pilot testing of the draft scale were carried out within research teams at 28 participant study sites in 27 countries. Twenty-five interviews were conducted at each site (total n=732) with five of the interviews at each site audio-taped, transcribed verbatim, translated into English and qualitatively analysed by members of the study team (Rose et al., 2011). The results of this study suggested that negative discrimination was frequently experienced. For example, 344 (47%) reported discrimination in making or keeping friends, 315 (43%) in relationships with family members, and 209 (29%) in finding a job. Discrimination was also frequently anticipated, with 469 (64%) inhibiting themselves from applying for work, training, or education and 402 (55%) stopping themselves from looking for a close relationship for this reason. This initial version of the scale also provided the opportunity for participants to record any experiences of positive discrimination (i.e. situations where they had been treated more positively because of their mental health problem). Reports of positive experienced discrimination were rare. The qualitative and quantitative analysis of the data collected suggested that the scale may benefit from further developmental work to improve the relevance and ease of use of items and response options. This article details this work and further work to establish the psychometric properties of the revised scale.
This study aims to
- (1)
complete the developmental work to maximise the acceptability and feasibility of the DISC, leading to a finalised version of the scale (Phase 1); and
- (2)
establish the psychometric properties of the revised DISC (Phase 2).
Section snippets
Methods for completing the development of the DISC
Firstly, the corrections indicated by the INDIGO data analyses were incorporated, as described elsewhere (the INDIGO Study Group, 2011, The INDIGO Study Group, 2009). As mentioned in Section 1, this focus improved the relevance and ease of use of items and response options. This included restructuring the response options from a 7-point Likert scale that allowed a rating of positive or negative discrimination on each items to a 4-point scale that allowed ratings of negative discrimination only.
Results of completing the development of the DISC
There were 13 participants in the service user focus groups and 12 in the interviewer focus groups. Males accounted for 39% of participants.The mean age of the participants was 46.8 (S.D.=13.42). Eighty percent reported some personal experience of stigma. Participants in the service user focus groups most commonly reported the following diagnoses: depression (n=3); schizophrenia (n=4); and bipolar disorder (n=6). In the interviewer focus groups participants had conducted there had been an
Discussion
This study conducted further developmental work and evaluated the psychometric properties of the DISC. The DISC was designed to address the need for a psychometrically validated measure which considers the scope and content of experienced discrimination. Experienced discrimination was conceptualised as reported instances of unfair treatment or discrimination due to having a mental health problem. This work led to a recommendation for the 22-item Unfair Treatment subscale to be used as a
Acknowledgements
Data collection assistance was given by Amy MacDonald, Gaby Illingsworth, Zoe Given-Wilson, Eleanor Parker, Manuela Jarrett, Tanya Graham, Georgia Black and Eleanor Lewis-Holmes. Dr Morven Leese provided statistical advice. This article presents independent research commissioned by the National Institute for Health Research (NIHR) under its Programme Grants for Applied Research scheme (RP-PG-0606–1053). The views expressed in this publication are those of the author(s) and not necessarily those
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MS and GT contributed equally to this manuscript.