OBJECTIVES : There has been a substantial increase in research on the effect of illness-related stigma on treatment outcomes and health-related quality of life (HRQoL). This study aims to provide an overview of conceptual and measurement considerations in assessing illness-related stigma in interventional contexts with a focus on mental illness and infectious diseases.

METHODS : This conceptual study will: 1) review published literature on the concept of stigma; 2) discuss the elements of stigma most suitable for use as an endpoint in interventional studies; and 3) present key stigma instruments in mental illness and infectious diseases with an evaluation of the suitability of instruments for use in an interventional context. The content validity, psychometric properties and interpretability of the instruments will also be considered.

RESULTS : The concept of stigma is multifaceted. Instruments in mental illness and infectious diseases focus mainly on assessing three elements of stigma including 1) perceived stigma, 2) experienced stigma and 3) self-stigma, consistent with the findings of a previously published review by Brohan and colleagues, 2010. Self-stigma is considered the element of stigma most suitable for use in patient-focused interventional studies; however, recommendations regarding perceived and experienced stigma are also presented. The conceptual and measurement differences in mental health and infectious diseases are further discussed with a focus on the need for disease-specific measures of illness-related stigma. The psychometric properties of the instruments vary, and there appears to be a lack of evidence on meaningful change for many of the instruments.

CONCLUSIONS : Incorporation of the assessment of illness-related stigma into interventional studies will assist in ensuring that the evaluation of new treatments incorporates key outcomes which impact treatment success and HRQoL for patients. Further research is needed to demonstrate the validity of many existing stigma instruments for use as endpoints in interventional studies.