Objective: To examine the risk factors for human immunodeficiency virus (HIV) transmission among attendees of public sexually transmitted infection clinics in Hong Kong.
Design: Retrospective matched case-control study.
Setting: All public sexually transmitted infection clinics in Hong Kong.
Patients: All public sexually transmitted infection clinic attendees' records from January 1995 to December 2002 were reviewed.
Main outcome measures: HIV sero-positivity in corresponding clinic attendees.
Results: A total of 196 HIV-positive cases among 149,336 sexually transmitted infection clinic attendees were recruited into the study. Multivariate analysis using conditional logistic regression revealed that HIV infection was associated with the following factors: belonging to non-Chinese ethnic groups (mainly South-East Asian) [odds ratio=9.32; 95% confidence interval, 3.27-26.55], coexisting syphilis (other than primary) [5.67; 1.66-19.36], current non-gonococcal urethritis (2.10; 1.08-4.07), current genital warts (1.94; 1.10-3.43), history of prior sexually transmitted infection (2.19; 1.29-3.72), having casual sex with friends (2.89; 1.07-7.80), and casual sex in Mainland China (1.91; 1.04-3.49). Sexual orientation was also considered to be a potential risk factor, as only those who tested positive reported to be homosexual or bisexual.
Conclusion: Sexually transmitted disease patients represent an identifiable group who are at high risk of HIV infection. This study found that there were certain factors which increased the risk of HIV infection among patients attending public sexually transmitted infection clinics. Targeted interventions should therefore be offered to such high-risk individuals, so as to prevent and control HIV transmission.