Psychometric evaluation of the internalized stigma of mental illness scale for patients with mental illnesses: measurement invariance across time

Chih-Cheng Chang; Tsung-Hsien Wu; Chih-Yin Chen; Jung-Der Wang; Chung-Ying Lin

doi:10.1371/journal.pone.0098767

Psychometric evaluation of the internalized stigma of mental illness scale for patients with mental illnesses: measurement invariance across time

PLoS One. 2014 Jun 2;9(6):e98767. doi: 10.1371/journal.pone.0098767. eCollection 2014.

Authors

Chih-Cheng Chang¹, Tsung-Hsien Wu², Chih-Yin Chen³, Jung-Der Wang⁴, Chung-Ying Lin⁵

Affiliations

¹ Department of Psychiatry, Chi Mei Medical Center, Tainan, Taiwan; Health Service and Population Research Department, Institute of Psychiatry, King's College London, London, United Kingdom; Department of Senior Citizen Service Management, College of Recreation and Health Management, Chia Nan University of Pharmacy and Science, Tainan, Taiwan.
² Department of Psychiatry, Chi Mei Medical Center, Liouying, Tainan, Taiwan.
³ Department of Senior Citizen Service Management, College of Recreation and Health Management, Chia Nan University of Pharmacy and Science, Tainan, Taiwan; Department of Nursing, College of Health Sciences, Chang Jung Christian University, Tainan, Taiwan.
⁴ Deparment of Public Health, College of Medicine, National Chen Kung University, Tainan, Taiwan; Departments of Internal Medicine and Occupational and Environmental Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.
⁵ Deparment of Public Health, College of Medicine, National Chen Kung University, Tainan, Taiwan.

Abstract

Background: The current investigation examined the psychometric properties of the Internalized Stigma of Mental Illness (ISMI) scale in a sample of patients with mental illness. In addition to the internal consistency, test-retest reliability, and concurrent validity that previous studies have tested for the ISMI, we extended the evaluation to its construct validity and measurement invariance using confirmatory factor analysis (CFA).

Methods: Three hundred forty-seven participants completed two questionnaires (i.e., the ISMI and the Depression and Somatic Symptoms Scale [DSSS]), and 162 filled out the ISMI again after 50.23±31.18 days.

Results: The results of this study confirmed the frame structure of the ISMI; however, the Stigma Resistance subscale in the ISMI seemed weak. In addition, internal consistency, test-retest reliability, and concurrent validity were all satisfactory for all subscales and the total score of the ISMI, except for Stigma Resistance (α = 0.66; ICC = 0.52, and r = 0.02 to 0.06 with DSSS). Therefore, we hypothesize that Stigma Resistance is a new concept rather than a concept in internalized stigma. The acceptable fit indices supported the measurement invariance of the ISMI across time, and suggested that people with mental illness interpret the ISMI items the same at different times.

Conclusion: The clinical implication of our finding is that clinicians, when they design interventions, may want to use the valid and reliable ISMI without the Stigma Resistance subscale to evaluate the internalized stigma of people with mental illness.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adult
Factor Analysis, Statistical
Female
Humans
Male
Mental Disorders / psychology*
Middle Aged
Psychometrics*
Stereotyping*

Grants and funding

This study was supported by grant CLFHR10028 from the Chi Mei Medical Center, Liouying, Taiwan. This research was, in part, supported by the Ministry of Education, Taiwan, R.O.C.; and the Aim for the Top University Project to the National Cheng Kung University (NCKU). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.