Final Research Plan

Syphilis Infection in Nonpregnant Adolescents and Adults: Screening

January 28, 2021

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Figure 1 is the analytic framework that depicts the three Key Questions to be addressed in the systematic review. The figure illustrates how screening for syphilis infection in asymptomatic nonpregnant adolescents and adults may result in improved health outcomes, including a reduction of transmission or acquisition of syphilis or other sexually transmitted infections, and a reduction of morbidity and mortality from syphilis (Key Question 1). Additionally, the figure illustrates whether risk assessment instruments or other risk stratification methods can identify asymptomatic nonpregnant adolescents and adults at increased risk for syphilis infection (Key Question 2). The figure also shows whether screening for syphilis infection is associated with any harms (Key Question 3).

  1. What is the effectiveness of screening for syphilis in reducing complications of the disease and transmission or acquisition of other sexually transmitted infections in asymptomatic, nonpregnant, sexually active adolescents and adults?
    1. What is the effectiveness of specific screening intervals and screening among population subgroups (e.g., based on demographic characteristics or risk factors)?
  2. What is the performance of risk assessment instruments or other risk stratification methods for identifying persons at increased risk for syphilis?
  3. What are the harms of screening (e.g., stigma, sequelae of test inaccuracy)?

Contextual questions will not be systematically reviewed and are not shown in the Analytic Framework. 

  1. Which population subgroups are at highest risk for incident syphilis infection and syphilis-related morbidity and mortality?
  2. What are the benefits and tradeoffs of screening with reverse sequence testing (i.e., using a treponemal test for initial screening followed by a nontreponemal test for confirmation) compared to the traditional sequence testing algorithm (i.e., a nontreponemal test followed by a treponemal test)?
  3. What is the clinical test performance of rapid point-of-care antibody tests?

The Research Approach identifies the study characteristics and criteria that the Evidence-based Practice Center will use to search for publications and to determine whether identified studies should be included or excluded from the Evidence Review. Criteria are overarching as well as specific to each of the key questions (KQs).

  Included Excluded
Populations Asymptomatic, nonpregnant adolescents and adults who are not known to have current syphilis infection, including persons who are infected with other STIs Symptomatic patients; neonates, infants, and children; pregnant persons; other populations in which syphilis screening may be part of disease management, such as persons living with HIV
Interventions KQs 1, 3: Two-step screening for syphilis with a nontreponemal and treponemal test (traditional or reverse sequence algorithm), including different screening intervals

KQ 2: Risk assessment instruments and other risk stratification methods that identify persons at increased risk for syphilis infection

KQs 1, 3: Screening tests not currently used in U.S. primary care settings
Comparisons KQ 1, 3: No screening

KQ 2: Reference standard (identification or diagnosis of infection)

 KQs 1, 3: No comparator or alternate screening test/algorithm
Outcomes KQ 1: Complications of syphilis infection and transmission or acquisition of STIs, including HIV

KQ 2: Any measure of discrimination (e.g., AUC, c-statistic) for identification of infection

KQ 3: Harms from screening (e.g., stigma, sequelae of test inaccuracy)

 KQ 1: Outcomes that are not directly related to health outcomes (e.g., laboratory studies); cost-effectiveness or cost-related outcomes
Setting Primary care and primary care–relevant settings (e.g., school-based clinics, family planning clinics, obstetrics and gynecology clinics, STI clinics, urgent care clinics, emergency departments, community settings, and correctional facilities)  
Study Design All KQs: Good-quality systematic reviews

KQs 1, 3: Randomized, controlled trials; observational studies with contemporaneous control groups

KQ 2: Risk prediction studies

KQs 1, 3: Observational studies without comparison groups or historical comparators; narrative reviews; editorials; case reports
Study Quality Good- and fair-quality Poor-quality
Language English Non-English studies
Country Studies conducted in countries categorized as “High” or Very High” on the 2019 Human Development Index (as defined by the United Nations Development Programme) Studies conducted in countries categorized as less than “High” or “Very High” on the 2019 Human Development Index

Abbreviations: AUC = area under the curve; c = concordance; HIV = human immunodeficiency virus; KQ = key question; STI = sexually transmitted infection; U.S. = United States.

The draft Research Plan was posted for public comment on the USPSTF website from November 19 through December 23, 2020. Comments generally requested clarification on considered outcomes, population diversity, nonpharmacologic treatments, testing regimen and harms, and inclusion of high-risk populations. Based on comments received, the USPSTF clarified the language about health outcomes in the analytic framework. The remaining comments were either already included in the research plan or out of scope for this review.