Background:
Universal chlamydia (CT) screening of men is standard practice at Region X STD clinics. This provides an opportunity to explore male trends in CT+ by demographics, sexual orientation, and risk behaviors.

Objective:
1) Assess CT trends and risk factors for men attending Region X STD clinics, 2000-2006; and 2) explore correlates and differences in CT+ by sexual orientation.

Method:
We analyzed universal male CT test records (N=99,413) from 112 Region X STD clinics, 2000-2006. We calculated chlamydia positivity by demographics, sexual orientation, risk behaviors, and clinical findings. Multivariate analyses (MVA) assessed CT trends and risk factors associated with infection for the total population and two sub-populations—men who have sex with men (MSM) (n=15,769) and heterosexual males (79,224 cases).

Result:
Overall CT positivity was 12.5% and ranged from 18.1% (Asian/Pacific Islander, API) to 10.2% (NH White). MSM CT+ was 8.7%; heterosexual CT+ was 13.1%. The MVA highlighted disparate risk factors for MSM and heterosexuals. For example, among heterosexuals, key risks were: age < 30 (OR=2.55), exposure to CT as visit reason (OR=7.72), and urethritis (OR=3.24). For MSM, CT fell significantly from 2000 to 2006 (visit year OR=0.89). Age <30 (OR=1.38), exposure to CT (OR=3.24), and urethritis (OR=1.53) were relatively less important for predicting CT among MSM. MSM testing volume increased from 1,800 (CY2000) to 3,033 (CY2006). Annual heterosexual testing volume remained stable.

Conclusion:
CT risk factors differed significantly for MSM and heterosexuals. Among MSM, CT positivity decreased over time while testing increased. For heterosexuals, visit reason and clinical signs suggest more recent CT acquisition; young age was also important. Racial/ethnic differences remained after adjusting for all other risks. API positivity was high.

Implications:
Given the declining MSM CT trend, additional work is needed to assess individual, sexual network and community factors. Further research on race/ethnic disparities is needed.