Screening for Chlamydial Infection U.S. Preventive Services Task Force Recommendation Statement

The U.S. Preventive Services Task Force (USPSTF) makes recommendations about preventive care services for patients without recognized signs or symptoms of the target condition. The USPSTF bases its recommendations on a systematic review of the evidence of the benefits and harms and an assessment of the net benefit of the service. The USPSTF recognizes that clinical or policy decisions involve more considerations than this body of evidence alone. Clinicians and policymakers should understand the evidence but individualize decision making to the specific patient or situation. Summary of Recommendation and Evidence The USPSTF recommends screening for chlamydial infection for all sexually active nonpregnant young women age 24 years or younger and older nonpregnant women who are at increased risk (Figure). This is a grade A recommendation. The USPSTF recommends screening for chlamydial infection for all pregnant women age 24 years or younger and for older pregnant women who are at increased risk (Figure). This is a grade B recommendation. The USPSTF recommends against routinely screening for chlamydial infection for women age 25 years or older, regardless of whether they are pregnant, if they are not at increased risk (Figure). This is a grade C recommendation. The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of screening for chlamydial infection for men (Figure). This is an I statement. See Table 1 for a description of the USPSTF grades and Table 2 for a description of the USPSTF classification of levels of certainty regarding net benefit. Both are also available at www.annals. org. Figure. Screening for chlamydial infection. For a summary of the evidence systematically reviewed in making these recommendations, the full recommendation statement, and supporting documents, please go to www.preventiveservices. ahrq.gov. *Chlamydial infection results in few sequelae in men. Therefore, the major benefit of screening men would be to reduce the likelihood that infected and untreated men would pass the infection to sexual partners. There is no evidence that screening men reduces the long-term consequences of chlamydial infection in women. Because of this lack of evidence, the USPSTF could not assess the balance of benefits and harms and concluded that the evidence is insufficient to recommend for or against routinely screening men. Information from reference 1. Table 1. What the U.S. Preventive Services Task Force Grades Mean and Suggestions for Practice* Table 2. U.S. Preventive Services Task Force Levels of Certainty Regarding Net Benefit See the Clinical Considerations section for discussion of assessing risk for chlamydial infection in women and suggestions for practice regarding screening for men. Rationale Importance Chlamydial infection is the most common sexually transmitted bacterial infection in the United States. In women, genital chlamydial infection may result in urethritis, cervicitis, pelvic inflammatory disease (PID), infertility, ectopic pregnancy, and chronic pelvic pain. Chlamydial infection during pregnancy is related to adverse pregnancy outcomes, including miscarriage, premature rupture of membranes, preterm labor, low birth weight, and infant mortality. Detection The USPSTF found fair evidence that nucleic acid amplification tests (NAATs) can identify chlamydial infection in asymptomatic men and women, including asymptomatic pregnant women, with high test specificity. In low-prevalence populations, however, a positive test result is more likely to be false positive than true positive, even with the most accurate tests available. Benefits of Detection and Early Intervention Nonpregnant Women at Increased Risk There is good evidence that screening for chlamydial infection in nonpregnant women who are at increased risk can reduce the incidence of PID. The USPSTF concluded that the benefits of screening nonpregnant women at increased risk are substantial. Pregnant Women at Increased Risk There are no studies evaluating the effectiveness of screening for chlamydial infection in pregnant women who are at increased risk. The USPSTF, however, found that 1) screening identifies infection in asymptomatic pregnant women, 2) there is a relatively high prevalence of infection among pregnant women who are at increased risk, and 3) there is fair evidence of improved pregnancy and birth outcomes for women who are treated for chlamydial infection. The USPSTF concluded that the benefits of screening pregnant women who are at increased risk are substantial. Women Not at Increased Risk The USPSTF identified no studies documenting the benefits of screening women, including pregnant women, who are not at increased risk for chlamydial infection. While recognizing the potential benefit to women identified through screening, the USPSTF concluded that the overall benefit of screening would be small, given the low prevalence of infection among women not at increased risk. Men While concluding that the direct benefit of screening in men was likely to be small, the USPSTF noted that screening for chlamydial infection in men may be beneficial if it were to lead to a decreased incidence of chlamydial infection in women. The USPSTF did not, however, find evidence to support this outcome and therefore concluded that the benefits of screening men are unknown. The USPSTF identified this as a critical gap in the evidence. Harms of Detection and Early Treatment The USPSTF concluded that the harms of screening for chlamydial infection are small, although few studies have been published on this subject. Potential harms include anxiety and relationship problems arising from false-positive results and overtreatment. The USPSTF identified the lack of evidence related to potential harms of screening as a gap in the evidence.The USPSTF reached the following conclusions: For nonpregnant women at increased risk, the certainty is high that the benefits of screening for chlamydial infection substantially outweigh the harms. This is a grade A recommendation. For pregnant women at increased risk, the certainty is moderate that the benefits substantially outweigh the harms of screening for chlamydial infection. This is a grade B recommendation. For women not at increased risk (including pregnant women not at increased risk), the certainty is moderate that the benefits outweigh the harms of screening to only a small degree. There may be considerations that support screening an individual patient. This is a grade C recommendation. For men, the benefits of screening are not known; thus, the USPSTF could not determine the balance of benefits and harms of screening men for chlamydial infection. This is an I statement. Clinical Considerations Patient Population under Consideration These recommendations target all sexually active individuals, including adolescents and pregnant women. Assessment of Risk All sexually active women 24 years of age or younger, including adolescents, are at increased risk for chlamydial infection. In addition to sexual activity and age, other risk factors for chlamydial infection include a history of chlamydial or other sexually transmitted infection, new or multiple sexual partners, inconsistent condom use, and exchanging sex for money or drugs. Risk factors for pregnant women are the same as for nonpregnant women. Prevalence of chlamydial infection varies widely among patient populations. African-American and Hispanic women have a higher prevalence of infection than the general population in many communities and settings. Among men and women, increased prevalence rates are also found in incarcerated populations, military recruits, and patients at public sexually transmitted infection clinics. Screening Tests Nucleic acid amplification tests have high specificity and sensitivity when used as screening tests for chlamydial infection. Nucleic acid amplification tests can be used with urine and vaginal swabs, enabling screening when a pelvic examination is not performed. Treatment Appropriate treatment of chlamydial infection has been outlined by the Centers for Disease Control and Prevention (CDC) (www.cdc.gov/std/treatment). In its 2006 sexually transmitted disease treatment guidelines, the CDC recommends that chlamydia infection be treated with 1 g of azithromycin in a single oral dose or with oral doxycycline, 100 mg twice daily for 7 days. Pregnant women with chlamydial infection may be treated with 1 g of azithromycin in a single oral dose or amoxicillin, 500 mg orally 3 times daily for 7 days (1). Because the CDC updates these recommendations regularly, clinicians are encouraged to access the CDC Web site (www.cdc.gov/std/treatment) to obtain the most up-to-date information. To prevent recurrent transmission, clinicians should ensure that all sexual partners of infected individuals are tested and treated if infected, or treated presumptively. Screening Intervals Screening pregnant women who are at increased risk for chlamydial infection is recommended at the first prenatal visit. For pregnant women who remain at increased risk and for those who acquire a new risk factor, such as a new sexual partner, a screening should be conducted during the third trimester. The optimal interval for screening for nonpregnant women is unknown. The CDC recommends at least annual screening for women at increased risk (1). Suggestions for Practice with regard to Insufficient Evidence on Screening in Men The USPSTF concluded that the evidence is insufficient to determine the balance of benefits and harms related to screening men for chlamydial infection. Specifically, the USPSTF did not find evidence that screening programs that target men result in a decreased incidence of infection in women. The USPSTF notes that programs that screen men as a means of reducing transmission to women are not common practice, that primary care clinicians can institute screening in men, that the costs of ad