Internal Structure and Reliability of the Internalized Stigma of Mental Illness Scale (ISMI 29) and Brief Versions (ISMI 10, ISMI 9) Among Americans With Depression
The Internalized Stigma of Mental Illness (ISMI) Scale is designed to measure self stigma among persons with psychiatric disorders. Research provides varying degrees of evidence supporting the reliability and validity of the original English language version of the ISMI 29 as well as an array of translated and/or modified versions for particular disorders or populations used with samples from around the world. The present paper is the first to use confirmatory factor analysis to investigate the internal structure of the English ISMI 29, ISMI 24 (a version that excludes the Stigma Resistance subscale) and ISMI 10 short form (ISMI 10) using a sample of 758 community dwelling adults who identified as depressed. Across all three versions, results of bifactor analyses and model based reliability estimates provided evidence for the calculation and interpretation of the total score as a measure of the general internalized stigma of mental illness construct, but did not support the use of individual subscales. Results also supported the inclusion of the Stigma Resistance subscale items when calculating the ISMI total scores. Also, a new 9 item unidimensional short form of the ISMI (ISMI 9) was developed and evaluated. Results suggested that the ISMI 9 may offer certain psychometric advantages over the ISMI 10. Researchers are strongly encouraged to conduct further internal structure analyses of the ISMI and its various alternate versions to determine the idiosyncrasy versus generalizability of the present findings.