METHODS: We analyzed inpatient and outpatient discharge datasets for chlamydia infection using ICD-9-CM codes for AI/ANs ages 10–49 years during 2001–2013. Combining hospitalizations and outpatient visits, we calculated overall rates and rates by age group, gender and year. Rates were calculated per 1,000 persons. Poisson regression was used to identify any trends. For 2013, the most recent year data were available, we calculated repeat visits defined as any visits with a chlamydia diagnosis occurring after the original chlamydia diagnosis.
RESULTS: A total of 181,878 chlamydia-associated hospitalizations (N=918) and outpatient visits (N=180,960) were observed from 2001–2013. Annual rates of chlamydia-associated encounters increased for all age groups for both males and females from 2001–2013. Rates increased from 19.4 (N=8,432) in 2001 to 28.4 (N=13,930) in 2013 for females (p<0.0001), and from 4.2 (N=1,683) to 7.0 (N=3,173) (p<0.0001) for males. In 2013, the highest rate of infection was among 20–24 years old females (64.8; N=5,077); among males, the highest rate was also in 20–24 year olds (15.4; N=1,076). Thirty-three percent (N=5,610) of people had a repeat visit and the median time between visits was 7 days. The average number of visits for a person was 1.8 (range: 1–13). For females, 34.7% (N=4,828) had a repeat visit with the majority of the repeat visits (78.6%) occurring less than 30 days from the initial visit. For males, 24.6% had a repeat visit, and 80.3% of those visits were in less than 30 days.
CONCLUSIONS: Increasing trends of chlamydia infection were observed among AI/ANs during 2001–2013, with young females mostly affected. In 2013, 33% of visits were repeat visits with the majority occurring within 30 days of the original visit, indicating that some repeat visits might be attributable to persistent chlamydia infection or reinfection. Our analysis demonstrates that discharge datasets could be used to enhance surveillance efforts to examine trends of chlamydia infection among AI/ANs.