Objective   To investigate the reality of participants.contact information and its affected factors among injection drug users (IDUs) in HIV sero-conversion cohort study in Liangshan, Sichuan province.

  Methods   From May to June, 2003, 62 month followup was conducted to conform participants.contact information by outreach group and seeds with designed forms.SPSS(11.5)was used to analyze data.

  Results   73.3% participants finished 62 month visit on time.After checking contact information, 28.5% participants were found providing false contact information.Age, education and inhabitation were significantly associated with providing false information and the risk factors of HIV infection were not found associated with providing false information after univariate analysis using the chi-squared test.Using multivariate logistic regression, age, education and inhabitation were significantly associated with providing false information.The retention rate of participants.providing real contact information (84.9%) was higher than that of the participants.providing false contact information (44.2%).After controlling sociodemographic variables and other risk factors, providing real contact information was significantly associated with retention rate at 62 month visit.

  Conclusion   Further studies should be conducted to investigate effects of sociodemographics and risk behavioral characteristics on providing false information.