Psychometric evaluation of the Health Care Provider HIV/AIDS Stigma Scale (HPASS) using Rasch analysis

The role of pharmacists is crucial in the care of individuals with HIV/AIDS. However, stigma in health care settings can be a deterrent to providing appropriate care. This paper assessed psychometric properties and convergent validity of the Health Care Provider HIV/AIDS Stigma Scale (HPASS) among pharmacy students in the United States (US) using Rasch analysis.

Students enrolled in four US universities were administered the survey (N = 203). Rasch analysis was conducted for each HPASS subscale (Stereotyping, Discrimination, and Prejudice) to assess dimensionality, model data fit, item difficulty, individual stigma, distribution of items and persons across item-person map, and rating scale function. Convergent validity evidence was established by comparing Pearson's correlation coefficients between HPASS subscales and the AIDS Attitude Scale (AAS) Avoidance subscale.

Two items in the Prejudice subscale were misfit and therefore removed. The 6-point rating scale did not perform satisfactorily for HPASS subscales. Item difficulty ranges were wide [Stereotyping (-5 to 0.8 logits), Discrimination (-6 to 1 logits), Prejudice (-5 to 0.4 logits)]. Items were biased towards measuring higher levels of stigma. Person separation index was satisfactory (Stereotyping = 2.2; Discrimination = 2.06; Prejudice = 2.17) as was person separation reliability (Stereotyping = 0.83; Discrimination = 0.81; Prejudice = 0.83). Convergent validity was established by showing significant correlations between HPASS subscales and AAS Avoidance (P < .001).

Modifying or removing misfit items of HPASS and exploring alternate rating scales for HPASS subscales will help better assess HIV/AIDS related stigma among pharmacy students.