Background:
The Region X Infertility Prevention Project (IPP) provides screening for C. trachomatis (CT) and treatment of women at 150 family planning (FP) clinics.

Objective:
1) Assess CT trends and risk factors associated with infection among women aged 15-24 years attending FP clinics from 1997-2006; 2) explore race/ethnic CT differences using area-based socioeconomic measures (ABSM).

Method:
CT positivity was calculated by demographics, behavioral risks (new, symptomatic, or multiple partners), and clinical findings for 743,290 tests among female FP clients aged 15-24 years from 1997-2006. ABSM were generated from U.S. Census 2000 data and matched to test records via client ZIP codes. CT positivity was assessed for ABSM, including: population density, median household income, race/ethnic minority, and educational attainment. Multivariate models were used to assess differences and temporal trends in CT for the total sample and each race/ethnic group.

Result:
47% of tests were from clients aged 15-19 years; 76% from non-Hispanic (NH) Whites. Overall CT positivity was 5.4% and varied by race/ethnicity (NH Blacks: 10.0% to NH Whites: 4.7%). Individual-level risk factors for CT included visit year (OR=1.03), age < 20 years (OR=1.32), race/ethnicity (NH Black: OR=1.84; AI/AN: OR=1.69; API: OR=1.34, Hispanic ethnicity: OR=1.24), CT infection past year (OR=1.62), diagnosis by NAAT (OR=1.29), behavioral risks (OR=1.93); and clinical findings (cervicitis or PID) (OR=3.03). ABSM for low income, race/ethnic minority population and low educational attainment increased CT risk; rural residence was protective.

Conclusion:
Estimated CT positivity increased annually after adjusting for risk factors, socioeconomic variables and test type. Race/ethnic differences remain after accounting for behavior, CT history, clinical findings, and ABSM.

Implications:
CT race/ethnic differences—and variation in individual risk factors and ABSM within groups—suggest customizing interventions to local conditions. Additional work is needed to assess individual behaviors and sexual networks as explanatory variables underlying apparent associations between CT, socioeconomic status, and race/ethnicity.