Bifactor SEM and MIRT Structure of a 12-Item Human Immunodeficiency Virus Stigma Scale in Peruvian Adults

BACKGROUND: The stigma associated with human immunodeficiency virus (HIV) can lead to prejudice and discrimination against people who have been infected by this virus, consequently, it is important to have a validated tool to measure this phenomenon. However, there is only 1 national precedent that has validated the scores of this instrument in its 21-item version. Therefore, this study examined the bifactor structural equation method (SEM) and multidimensional item response theory (MIRT) structure of a 12-item human immunodeficiency virus stigma scale in Peruvian adults. METHODS: We evaluated 342 patients (57.6% female and 42.45% male) diagnosed with HIV receiving highly active antiretroviral therapy (HAART) from a hospital located in East Lima, aged 18 to 45 years (M = 31.4, SD = 9.79). A SEM was used to test 2 measurement models, a 4-factor correlated oblique model and a bifactor model due to high interfactor relationships. RESULTS: Acceptable fit indices were identified for the oblique model (χ(2)/df = 1.26, SRMR = 0.044, RMSEA [90% CI] = 0.028 [0.000-0.047], CFI = 0.996, TLI = 0.994). In the same way, similar results were evident for the bifactor model (χ(2)/df = 1.14, SRMR = 0.039, RMSEA [90% CI] = 0.020 [0.000-0.044], CFI = 0.998, TLI = 0.997), however, in the latter it showed a greater explanation for the unidimensional model (H = 0.87, PUC = 0.82, LCA = 0.70), which was also evidenced by the bifactor MIRT analysis. CONCLUSION: It is concluded that the 12-item HIV Stigma Scale meets the psychometric properties of internal structure and unifactorial reliability.