The current risk-based chlamydia screening strategy has provided evidence for a growing infection crisis, and yet at the same time contributes to the alarming infection problem by not adequately screening infected women. Most chlamydia infections are asymptomatic and, therefore, many unknowingly infected patients are not motivated to visit a physician, receive a diagnosis, and have their case reported. This causes infection prevalence to be underestimated.Screening practices themselves can also influence prevalence statistics. Today, the U.S. Preventive Services Task Force (USPSTF) and the Centers for Disease Control and Prevention (CDC) recommend screening of all sexually active women aged <25 years and screening of older women at increased risk (for example, women who have new or multiple sex partners). In the absence of more rigorous screening for infections, reported prevalence will be artificially low. The CDC estimates that 1.6 million people in the United States are currently infected with chlamydia trachomatis (chlamydia), making this bacterial infection the most common notifiable sexually transmitted infection (STI) in the U.S.1
Barriers to chlamydia screening
Screening rates in the U.S. are especially low for young adults.2 Only 40 percent of sexually active women aged 15 to 21 reported having had a chlamydia test in the past 12 months.3 Screening rates were lowest among patients aged 15 to 19—the cohort with the highest chlamydia prevalence.3 The CDC has estimated the chlamydia prevalence of sexually active persons aged 14 to 19 to be 6.8 percent.3
Too many women, especially young women, are not screened for chlamydia, leaving them vulnerable to the health problems that arise from untreated infection and increasing the likelihood that they will infect others. There are multiple interrelated barriers to adequate screening that compromise risk-based screening efficacy. Some physicians are not aware of the USPSTF and CDC recommendations and, in turn, do not incorporate regular screening into their practice. Others lack information about the sexual activity of their patients and therefore cannot act based on patient infection risk. The underlying reasons for this information gap relate to the fact that patients do not always fully disclose their sexual activity. The upshot of this situation is that physicians, who are aware of the unreliability of sexual history information provided by patients, simply stop asking about patient sexual activity and are in no position to accurately assess risk.
Health risks of untreated chlamydia
Untreated, chlamydia infection in women can persist and lead to complications that can have a lifelong impact.4 Chlamydia can spread to the uterus, ovaries, or fallopian tubes, causing pelvic inflammatory disease (PID). PID can lead to infertility, persistent (chronic) pelvic pain, and an increased risk of ectopic pregnancy. Additionally, if a chlamydia infection is present during pregnancy, there is a potential risk that the infection could be transferred to the fetus and cause conjunctivitis and pneumonia. Chlamydia left untreated during pregnancy may also increase the risk of premature birth, miscarriage, or stillbirth.
Proposal for universal screening
A cost-effectiveness study evaluated a universal screening method designed to overcome some of the barriers inherent in the risk-based strategy. A universal screening approach means that all women between 15 and 24, regardless of what the physician knows about patient sexual activity, would be informed that screening is routine, and unless they elect to “opt-out,” they will be screened annually. This screening as a default practice avoids the opportunity for infection risk misrepresentation/misunderstanding, and it also opens a dialogue about chlamydia infection between patients and physicians.
Cost-effectiveness of universal screening
Universal screening for chlamydia, by design, would screen more women than risk-based screening and for that reason could be mistakenly presumed to cost more. To evaluate whether the benefits accrued from identifying and treating more infected women might offset the operational costs of testing kits, a recent study evaluated the cost-effectiveness of universal screening for high-risk young women aged 15 to 24 in the U.S.2 The study used a basic compartmental heterosexual transmission model that assumed 80 percent insurance coverage, 83 percent healthcare utilization, and 75 percent test acceptance. The model expected an annual testing coverage rate of 50 percent compared with risk-based screening (30 percent).
Results of this modeling study predicted that the universal testing strategy would decrease overall chlamydia prevalence by >55 percent (2.7 percent to 1.2 percent) compared with risk-based screening. In addition, this strategy would reduce costs by improving health outcomes more than current testing. Costs in this study include costs of testing, costs of treatment, and costs related to subsequent patient outcomes. According to the modeling, predicted cost outcomes for a hypothetical population of 100,000 individuals aged 15 to 24 years would be $105 million for no screening, $89 million for risk-based screening, and $71 million for universal screening. The study concluded that decreasing infection prevalence, spread of infection, and adverse consequences of disease has cost benefits that offset the cost of testing more women.
Current risk-based screening for chlamydia is leaving too many women, particularly young adults, out at a time when infection rates are soaring. Not identifying and not treating women with infections promotes the likelihood of long-term negative health consequences that could have been prevented and enables the continuation of the infection cycle through partners of infected women. Laboratory professionals serve as integral partners to physicians in the chlamydia screening process. By advocating for a universal screening strategy with physician and healthcare partners, laboratorians can accelerate the transition to a viable, cost-effective method to lower chlamydia prevalence and raise the standard of care.
- Centers for Disease Control and Prevention. Chlamydia—2016 Sexually Transmitted Diseases Surveillance. https://www.cdc.gov/std/stats16/chlamydia.htm
- Owusu-Edusei K, Hoover KW Gift TL. Cost-effectiveness of opt-out chlamydia testing for high risk young women in the U.S. Amer J Prevent Med. 2016;51(2):216-224
- Hoover KW, Leichliter JS, Torrone, EA, Loosier PS, Gift TL, Tao G. Chlamydia Screening Among Females Aged 15–21 Years—Multiple Data Sources, United States, 1999–2010. MMWR. 2014; 63(02):80-88
- Centers for Disease Control and Prevention. Chlamydia—CDC Fact Sheet. https://www.cdc.gov/std/chlamydia/stdfact-chlamydia-detailed.htm
Michael D. Randell, MD, FACOG, serves on the Medical Staff at Emory Saint Joseph’s Hospital in the Department of Surgery, Division of Gynecology. He is the Medical Director of the Center for Menstrual Disorders and Reproductive Health, a Diplomate of the American Board of Obstetrics and Gynecology and the National Board of Medical Examiners, and a Fellow of the American College of Obstetricians and Gynecologists.