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Repeat Chlamydia Diagnoses Increase the Hazard of Pelvic Inflammatory Disease among US Army Women

A Retrospective Cohort Analysis

Bautista, Christian T., PhD, MSc, MPH*; Hollingsworth, Bruce P., PhD*; Sanchez, Jose L., MD, MPH

doi: 10.1097/OLQ.0000000000000878
Original Studies

Background In the US military, chlamydia is the mostly commonly diagnosed bacterial sexually transmitted infection and the rates of pelvic inflammatory disease (PID) have remained high since the early 2000s.

Methods The relationship between the number of chlamydia diagnoses and hazard of PID was investigated in a retrospective cohort analysis among US Army women from 2006 to 2012. Cox regression model was used to estimate hazard ratios for associations between the number of repeat chlamydia diagnoses and PID.

Results The study population comprised 33,176 women with chlamydia diagnosis. Of these, 25,098 (75%) were diagnosed only once (“nonrepeaters”). By comparison, 6282 (19%), 1435 (4%), and 361 (1%) women had one, two and three repeat chlamydia diagnoses, respectively. Among these 4 groups, 1111, 325, 72, and 25 PID diagnoses were noted. According to the Cox regression analysis, for every additional diagnosis of chlamydia, the hazard of PID increased by 28% (95% confidence interval, 19%–38%) compared with women with a single diagnosis or nonrepeaters. Moreover, the corresponding adjusted hazard ratio of 1.28, 1.35, and 1.97 represented a significantly greater risk for PID among the three “repeater” groups compared with nonrepeaters.

Conclusions We found an increased hazard of PID among US Army women with repeat chlamydia diagnoses and the characterization of a dose-response relationship. These findings reinforce the notion that early diagnosis and treatment of chlamydia is necessary to avoid subsequent PID and associated morbidity.

The hazard of PID increased significantly with the number of repeat chlamydia diagnoses among US Army females.

From the *Division of Health Research, Lancaster University, Lancaster, United Kingdom; and

Armed Forces Health Surveillance Branch, Public Health Division, Defense Health Agency, Silver Spring, MD

Acknowledgments: The authors thank Dr Angelia Cost at the Epidemiology and Analysis section of the US Armed Forces Health Surveillance Branch for DMSS data extraction for this study and Sebastian-Santiago for technical assistance. Moreover, they would like to thank Eyako Wurapa, LTC, MC USA (Ret), Walter Reed Army Institute of Research, for his leading role and scientific support during the course of this research. The study was approved by scientific review and institutional review boards at Lancaster University and at the Walter Reed Army Institute of Research.

Conflict of Interest and Sources of Funding: The authors declare no conflict of interest. This study was funded by the US Armed Forces Health Surveillance Branch and its Global Emerging Infections Surveillance section. The funder had no role in the study design, data analysis, or interpretation of findings, as well as in the writing and publication of this report.

Disclaimer: The views expressed herein are those of the authors and do not reflect the official policy or position of the Department of the Army, Department of Defense, the US government, or any organization listed. One of the authors (J.L.S.) was a contractor at the time of this study and now is an employee of the US government. This work was prepared as part of his official duties, and as such, there is no copyright to be transferred. This article was approved for publication by the Defense Health Agency, the Office of the Assistance Secretary of Defense for Health Affairs, as well as by the Department of Defense's Office of Prepublication and Security Review.

Correspondence: Christian T. Bautista, PhD, MSc, MPH, Division of Health Research, Lancaster University, Bailrigg, Lancaster LA1 4YG, Lancaster, United Kingdom. E-mail:;

Received for publication March 22, 2018, and accepted May 29, 2018.

© Copyright 2018 American Sexually Transmitted Diseases Association