Abstract: Objective To understand behavior characteristics of men who sexual with men（MSM） aged ≥45 years old in Xiqing District of Tianjin,explore the influencing factors of human immunodeficiency virus（HIV） infection,and provide reference for proposing targeted prevention and intervention measures. Methods A one-on-one questionnaire survey and HIV testing were conducted among MSM population aged≥45 years old who had participated in the special survey of high-risk population in Xiqing District from January 2021 to October 2024,and the data were analyzed. Results A total of 334 people were recruited with the HIV positive rate of 4.49%. 82.04% subjects had 1~5 sexual partners within three months. 47.60% subjects had consistently used condoms in the past three months. The condom use rate was 45.81% during the most recent sexual intercourse. The multivariate analysis showed that aged ≥50 years old was the risk factor of HIV infection,and their HIV infection risk was 3.74 times higher than that of survey respondents aged 45-<50（OR=3.74,95%CI：1.08-13.00,P<0.05）. The subjects having at least six homosexual partners within three months was the risk factor of HIV infection,and their HIV infection risk was 10.81 times higher than that of subjects had 0 partners（OR=10.81,95%CI：1.01-115.41,P<0.05）. The subjects did not use condoms during sexual activity within three months was the risk factor for HIV infection,and their HIV infection risk was 15.04 times higher than that of subjects consistently used condoms within three months（OR=15.04,95%CI：3.00-73.68,P<0.01）. Conclusions The risk factors for HIV infection in MSM population aged ≥45 years old include age ≥50 years old,multiple sexual partners and unprotected sex. This population has become the focus of AIDS intervention in Xiqing District. It is necessary to strengthen publicity,education and intervention testing among them,and improve the condom use rate,so as to effectively reduce the risk of HIV infection among middle-aged and elderly MSM population.

Key words: Middle aged and elderly, Men who sexual with men, Human immunodeficiency virus infection, Influencing factors