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Open Access Highly Accessed Research article

Psychometric assessment of HIV/STI sexual risk scale among MSM: A Rasch model approach

Jian Li12*, Hongjie Liu2, Hui Liu1, Tiejian Feng3 and Yumao Cai3

Author Affiliations

1 National Center for AIDS/STD Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China

2 Department of Epidemiology and Community Health, School of Medicine, Virginia Commonwealth University, Richmond, Virginia, USA

3 Department of HIV/STD Control and Prevention, Shenzhen Center for Chronic Disease Control, Shenzhen, China

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BMC Public Health 2011, 11:763  doi:10.1186/1471-2458-11-763

Published: 5 October 2011

Abstract

Background

Little research has assessed the degree of severity and ordering of different types of sexual behaviors for HIV/STI infection in a measurement scale. The purpose of this study was to apply the Rasch model on psychometric assessment of an HIV/STI sexual risk scale among men who have sex with men (MSM).

Methods

A cross-sectional study using respondent driven sampling was conducted among 351 MSM in Shenzhen, China. The Rasch model was used to examine the psychometric properties of an HIV/STI sexual risk scale including nine types of sexual behaviors.

Results

The Rasch analysis of the nine items met the unidimensionality and local independence assumption. Although the person reliability was low at 0.35, the item reliability was high at 0.99. The fit statistics provided acceptable infit and outfit values. Item difficulty invariance analysis showed that the item estimates of the risk behavior items were invariant (within error).

Conclusions

The findings suggest that the Rasch model can be utilized for measuring the level of sexual risk for HIV/STI infection as a single latent construct and for establishing the relative degree of severity of each type of sexual behavior in HIV/STI transmission and acquisition among MSM. The measurement scale provides a useful measurement tool to inform, design and evaluate behavioral interventions for HIV/STI infection among MSM.