title: Psychometric assessment of HIV/STI sexual risk scale among MSM: a Rasch model approach.
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.
authors.affiliation: National Center for AIDS/STD Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China. jli4@vcu.edu
authors.forename: Jian
authors.initials: J
authors.lastname: Li
authors.forename: Hongjie
authors.initials: H
authors.lastname: Liu
authors.forename: Hui
authors.initials: H
authors.lastname: Liu
authors.forename: Tiejian
authors.initials: T
authors.lastname: Feng
authors.forename: Yumao
authors.initials: Y
authors.lastname: Cai
mesh_terms: D000293:Adolescent; D000328:Adult; D002681:China; D003430:Cross-Sectional Studies; D006678:HIV; D015658:HIV Infections / Q000523:psychology*; D018451:Homosexuality, Male / Q000523:psychology*; D006801:Humans; D008297:Male; D011594:Psychometrics / Q000379:methods; D015203:Reproducibility of Results; D012309:Risk-Taking; D012725:Sexual Behavior / Q000523:psychology*; D012749:Sexually Transmitted Diseases / Q000523:psychology*; D014894:Weights and Measures; D055815:Young Adult