The psychometric assessment of internalized stigma instruments: a systematic review

Objective: To rate the psychometric properties of instruments to measure internalized (or self-) stigma in health conditions where stigma plays a major role. Method: We conducted a systematic literature review by searching relevant databases and by reviewing the bibliographies of relevant papers. Quantitative studies were included if the items used, or a sample of the instrument, was included in the paper and if the studies focussed on the initial development or validation of the instrument. Health conditions included were HIV/AIDS, mental health, leprosy, asthma, epilepsy, cancer, obesity, and tuberculosis. Psychometric properties of the included studies were assessed using the quality criteria proposed by Terwee et al. and the COSMIN consortium: content validity, internal consistency, construct validity, criterion validity, reproducibility, responsiveness, floor and ceiling effects, and interpretability. Results: Thirty-three papers were included of which 21 were identified as actual instrument development studies. Only two instruments received three positive quality ratings, 12 received at least three indeterminate ratings, especially for the internal consistency and construct validity. At least one negative rating was given to five instruments. Content and construct validity as well as internal consistency were most often assessed, whereas agreement and responsiveness received least attention. Conclusions: We rated the psychometric properties of available instruments to measure internalized stigma using standard quality criteria. Only the Child Attitude Towards Illness Scale and the Internalized Stigma of Mental Illness received three positive ratings indicating that the majority of the instruments need further testing. Implications: The need was identified for a simplified testing protocol to design an instrument development study, to assess certain psychometric properties, and to specify the preferred statistical methods for testing these. In addition, researchers should be aware that re-validation of instruments is necessary before they are used in cultures and study populations other than those for which they were developed.