Validation of a modified Berger HIV stigma scale for use among patients with hepatitis C virus (HCV) infection

Stigma around hepatitis C virus (HCV) infection is an important and understudied barrier to HCV prevention, treatment, and elimination. To date, no validated instrument exists to measure patients' experiences of HCV stigma. This study aimed to revise the Berger (2001) HIV stigma scale and evaluate its psychometric properties among patients with HCV infection. The Berger HIV stigma scale was revised to ask about HCV and administered to patients with HCV (n = 270) in Philadelphia, Pennsylvania. Scale reliability was evaluated as internal consistency by calculating Cronbach's alpha. Exploratory factor analysis was performed to evaluate construct validity by comparing item clustering to the Berger HIV stigma scale subscales. Item response theory was employed to further evaluate individual items and to calibrate items for simulated computer adaptive testing sessions in order to identify potential shortened instruments. The revised HCV Stigma Scale was found to have good reliability (α = 0.957). After excluding items for low loadings, the exploratory factor analysis indicated good construct validity with 85% of items loading on pre-defined factors. Analyses strongly suggested the predominance of an underlying unidimensional factor solution, which yielded a 33-item scale after items were removed for low loading and differential item functioning. Adaptive simulations indicated that the scale could be substantially shortened without detectable information loss. The 33-item HCV Stigma Scale showed sufficient reliability and construct validity. We also conducted computer adaptive testing simulations and identified shortened six- and three-item scale alternatives that performed comparably to the original 40-item scale.