Background:
Multiple prior studies have demonstrated high levels of Chlamydia trachomatis (CT) infections within American Indian and Alaskan Native (AI/AN) populations.

Objective:
To describe trends in population characteristics, CT positivity, and risk factors associated with chlamydial infection among AI/AN women.

Method:
We analyzed data from 7374 visits at which diagnostic tests for CT were collected in AI/AN women aged 15 to 24 years seen at family planning clinics associated with the Region X Infertility Prevention Project. Time trends in population characteristics and test positivity were examined and compared to non-AI/AN women tested in the same setting and time period. Chlamydia positivity was adjusted for changes in diagnostic test type to account for the use of newer assays. Multivariable logistic regression was used to identify characteristics independently associated with infection.

Result:
Adjusted CT positivity in AI/AN women ranged from 7.8% to 12.1%, which was 1.4 to 2.0 times the Region X general population levels over the study period (absolute difference 2.7% - 6.1%), with differences persisting after correction for test type and age. Temporal changes in positivity among AI/AN women were correlated with a rise in reported risk behaviors and a decline in age of the population tested. Risk factors associated with chlamydia positivity among AI/AN women were younger age, one or more behavioral risks, one or more clinical findings on exam, a partner with chlamydia, chlamydia in the past year, and pregnancy related visit.

Conclusion:
AI/AN women in Region X had consistently higher levels of chlamydia positivity than non-Native women, even after adjustment for age and diagnostic test.

Implications:
Further investigation of risks for chlamydia, related outcomes, access to screening, sexual networks, and enhanced surveillance would be beneficial for improving health in this vulnerable population.