·To introduce the Brief human immunodeficiency virus (HIV) Knowledge Questionnaire (HIV-KQ-18), evaluate the reliability and validity of the scale in the HIV-negative sexually transmitted diseases (STD) patients, and predict the population's sexual behavior based on its knowledge score.

·A total of 599 eligible patients who attended the outpatient clinic of Shanghai Skin Disease Hospital from January 2018 to December 2018 were evaluated by the Chinese version of HIV-KQ-18, and they were randomly allocated into two groups for exploratory factor analysis (n=300) and confirmatory factor analysis (n=299). Consistent condom use when having sex was judged as safe sexual behavior and used as a dependent variable, and HIV-KQ-18 scores were used as independent variables for receiver operating characteristic curve analysis to predict safe sexual behavior.

·The exploratory factor analysis showed that three factors including the transmission of HIV (7 items), preventive measures (4 items) and consequences of being infected with HIV (3 items) could be extracted. Four items were removed from HIV-KQ-18 to form the Chinese version of HIV-KQ-14. Confirmatory factor analysis showed that the model revised by three factors fitted well (χ²/df=2.046, root mean square error of approximation=0.059, incremental fit index=0.926, Tucker-Lewis index=0.908, comparative fit index=0.925). The Cronbach′s α of the scale was 0.861, and the Spearman-Brown coefficient was 0.815; the area under the curve of safe sexual behavior was 0.708 (P=0.000).

·The Chinese version of the HIV-KQ-14 has good reliability and validity in HIV-negative STD patients, and has a good predictive ability for safe sexual behavior.