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Release Date: July 29, 2004; Valid for credit through July 29, 2005

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July 29, 2004 — The U.S. Preventive Services Task Force (USPSTF) updated their guidelines for screening for syphilis and published them in the July/August issue of the Annals of Family Medicine.

Updating its 1996 recommendation, the USPSTF issued a statement strongly recommending screening tests for pregnant women (A recommendation) and for people who are at higher risk for syphilis infection (A recommendation). These recommendations have not changed from the 1996 guidelines, but the statement was updated after review of the evidence from 1994 to 2003 because the USPSTF criteria to rate the strength of the evidence have changed.

"Although the USPSTF found no new direct evidence that screening for syphilis infection leads to improved health outcomes in persons at increased risk, there is adequate evidence that screening tests can adequately detect syphilis infection and that antibiotics can cure syphilis," write Ned Calonge, MD, MPH, and colleagues from the USPSTF.

All pregnant women should be tested at their first prenatal visit, with repeat serologic testing in the third trimester in high-risk groups. High-risk populations include men who have sex with men and engage in high-risk sexual behavior, commercial sex workers, persons who exchange sex for drugs, and those in adult correctional facilities. Optimal screening frequency has not been determined for these high-risk populations.

Commonly used screening tests include the Venereal Disease Research Laboratory (VDRL) or rapid plasma reagin (RPR). Confirmatory tests are the fluorescent treponemal antibody absorbed (FTA-ABS) or Treponema pallidum particle agglutination (TP-PA).

The USPSTF recommends against routine screening of asymptomatic persons who are not at increased risk for syphilis infection (D recommendation). There is no evidence supporting routine screening for syphilis of individuals diagnosed with other sexually transmitted diseases.

"Given the low incidence of syphilis infection in the general population and the consequent low yield of such screening, the USPSTF concludes that potential harms of screening (i.e., opportunity cost, false-positive tests, and labeling) in a low-incident population outweigh the benefits," the authors write.

Ann Fam Med. 2004;2:362-365

Learning Objectives for This Educational Activity

• List the prevalence and risk factors for syphilis.
• Describe the current USPSTF screening guidelines for syphilis infection.

Clinical Context

In 2002, the nationwide incidence of primary and secondary syphilis was 2.4 per 100,000 persons, and the rate of congenital syphilis was 11.1 per 100,000 live births. Prevalence is higher in the South (3.1 per 100,000) compared with the Northeast (1.7 per 100,000) of the U.S. and in blacks and Hispanics compared with whites. Rates of primary and secondary syphilis had declined in the 1990s but increased for the first time in a decade in 2001. The increase was evident only in men, associated with high rates of HIV coinfection, men who had sex with men, and high-risk sexual behavior. Median seropositivity has been reported as 2.1% to 12.1% in incarcerated women and 0.9% to 5.2% in incarcerated men.

Populations at increased risk include those who engage in high-risk sexual behavior, persons diagnosed with other sexually transmitted disease, men who have sex with men, commercial sex workers, those who exchange sex for drugs, and incarcerated adults.

This report updates the 1996 USPSTF recommendations for syphilis screening and includes levels of evidence for each recommendation.

Study Highlights

• There is adequate evidence that screening can accurately detect syphilis infection and antibiotics (penicillin G) can cure syphilis. But, little evidence exists to guide treatment in pregnancy.
• There is no direct evidence that screening for syphilis in general or high-risk populations reduces morbidity of mortality.
• There is observational evidence that screening in pregnancy and/or neonates reduces the prevalence of congenital syphilis in neonates.
• Clinicians should use their best judgment to individualize screening based on local prevalence and other risk factors.
• Testing is two-step and involves using first, the VDRL or RPR, followed by a confirmatory treponemal test (FTA-ABS or TP-PA).
• Sensitivity of the RPR and VDRL is from 78% to 86% for primary syphilis, 100% for secondary syphilis, and from 95% to 98% for latent syphilis. Specificity is 85% to 99% and reduced by preexisting conditions, such as collagen vascular disease, pregnancy, intravenous drug use, malignancy, tuberculosis, malaria, and viral and rickettsial disease.
• The FTA-ABS has a sensitivity of 84% for primary syphilis and 100% for other syphilis. Specificity is 96%.
• Newer screening tests include immunochromatic strip, line immunoassay, enzyme-linked immunosorbent assay, RPR card, and rapid syphilis test (RST). New screening tests for pregnant women and infants include IgM immunoblocking and polymerase chain reaction assay of serum and cerebrospinal fluid, placenta, and umbilical blood testing.
• In a general population with prevalence of 5 per 100,000, 24,000 patients will need to be screened to detect one case of syphilis (number needed-to-screen [NNS], 24,000). 200 per 100,000 people screened would have false-positive results.
• In a high-risk population (such as incarcerated women) with prevalence of 12%, the NNS would be 10. 2,000 per 100,000 people screened would have false-negative results.

The recommendations are as follows:

1. Clinicians should screen all pregnant women for syphilis infection (A recommendation, ie, strongly recommends for). All women should be tested at the first prenatal visit. In high-risk groups, repeat serology should be performed in the third trimester and at delivery. If results are positive, follow-up tests should be performed after treatment using the same treponemal test to ensure comparability and to assure decline in titers. Seven cost studies have shown cost-effectiveness of syphilis-screening programs in pregnancy.
2. The benefits of screening all pregnant women includes reduced incidence of congenital syphilis, and they outweigh the potential harms (such as false-positive tests and adverse drug effects associated with treatment).
3. The USPSTF recommends against screening asymptomatic individuals not at increased risk for syphilis (D recommendation, ie, strongly recommends against routine use) because of low prevalence and potential harm (opportunity cost, false-positive tests, and labeling) outweighs the benefits.

Pearls for Practice

• Prevalence of syphilis in the U.S. is increased in high-risk populations, which include those who engage in high-risk sexual behavior, persons diagnosed with other sexually transmitted disease, men who have sex with men, commercial sex workers, those who exchange sex for drugs, and incarcerated adults.
• The USPSTF recommends universal screening for syphilis in pregnant women and in people who are at high-risk for syphilis infection. The USPSTF does not recommend routine screening for syphilis in asymptomatic, low-risk individuals.

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Target Audience

This article is intended for primary care physicians, public health physicians, infectious disease specialists, and other specialists who care for patients at risk of syphilis.

Goal

The goal of this activity is to provide the latest medical news to physicians and other healthcare professionals in order to enhance patient care.

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As an organization accredited by the ACCME, Medscape requires authors and editors to disclose any significant financial relationship during the past 12 months with the manufacturer of any product that may relate to the subject matter of the educational activity, whether or not the activity is commercially supported. Authors are also asked to disclose any mention of investigational products or unapproved uses of products regulated by the U.S. Food and Drug Administration.

News Author

Laurie Barclay, MD
Freelance writer for Medscape Medical News

Disclosure: Dr. Barclay has reported no significant financial interests.

Clinical Reviewer

Gary Vogin, MD
Senior Medical Editor, Medscape

Disclosure: Dr. Vogin has reported no significant financial interests.

CME Author

Désirée Lie, MD, MSEd
Associate Clinical Professor of Family Medicine and Director, Division of International Faculty Development, Irvine Medical Center, University of California, Irvine

Disclosure: Dr. Lie has reported no significant financial interests.

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