Past Issues

Reproducibility and Minimal Detectable Change of Internalized Stigma of Mental Illness (ISMI) Scale in Patients with Mental Illness

Chung-Ying Lin, Chih-Cheng Chang

Objective: Self-stigma which is a critical issue, needs to be cared by the mental health professionals, and the Internalized Stigma of Mental Illness (ISMI) scale
is one of the most commonly used instrument measuring self-stigma. But the information of its reproducibility, especially the minimal detectable change (MDC),
remains largely unknown. Therefore, the applicability of the ISMI is somewhat
limited. In this study, we intended to study the reproducibility of the ISMI in patients with mental illnesses through different lengths of test-retests. Methods:
People with mental illness (n = 145) completed the ISMI twice within an interval
of 2 weeks to 3 months; 116 of them within 2 months; and 75 within 1 month. The
intraclass correlation coefficient (ICC) was used to examine the reproducibility,
and MDC was further calculated using ICC results. Furthermore, MDC% was
computed to understand whether the reproducibility is acceptable (< 30% indicates
acceptable). Results: The reproducibility of the ISMI was better in a shorter testretest interval (3-month interval: ICC = 0.53 to 0.80; 2-month: ICC = 0.55 to 0.82;
1-month: ICC = 0.69 to 0.89). The MDC for the total score of the ISMI was 19.57
(three-month interval), 19.26 (two-month interval), and 14.08 (one-month interval). We also found that the patients had significantly reduced self-stigma in one
month (p < 0.05). MDC% revealed that the reproducibility for the total score of the
ISMI was nearly acceptable in three-month interval (30.16%) and acceptable in
2- and 1-month intervals (29.44% and 21.74%, p < 0.05). Conclusion: The total
score of the ISMI is reliable in monitoring the self-stigma in patients with mental
illness within an interval of two months.
Key Word reliability, mental illness, minimal detectable change, self-stigma
Editorial Committe, Taiwanese Journal of Psychiatry
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