Serologic testing for syphilis in the United States: a cost-effectiveness analysis of two screening algorithms

Sex Transm Dis. 2011 Jan;38(1):1-7. doi: 10.1097/OLQ.0b013e3181ec51f1.


Background: The introduction of automated treponemal enzyme immunoassays and chemiluminescence assays (EIA/CA) tests has led some laboratories in the United States to use new syphilis screening algorithms that start with a treponemal test. We compared the economic and health outcomes of this new algorithm with the standard algorithm from the perspective of the United States health system.

Methods: We used a cohort decision analysis to estimate the expected costs and effects (including follow-ups and overtreatment) of the 2 algorithms from a health-care system perspective. In the standard algorithm, rapid plasma reagin (RPR) is followed (if reactive) by EIA/CA (Nontreponemal-First). In the new algorithm, EIA/CA is followed (if reactive) by RPR. If the RPR is negative, Treponema pallidum passive particle agglutination assay (TP-PA) test is used (Treponemal-First).

Results: For a cohort of 200,000 individuals (1000 current infections and 10,000 previous infections), the net costs were $1.6 m (Treponemal-First) and $1.4 m (Nontreponemal-First). The Treponemal-First option treated 118 more cases (986 vs. 868) but resulted in a substantially higher number of follow-ups (11,450 vs. 3756) and overtreatment (964 vs. 38). Treating the additional 118 cases might prevent 1 case of tertiary syphilis. The estimated cost-effectiveness ratios were $1671 (Treponemal-First) and $1621 (Nontreponemal-First) per case treated. The overtreatment was a function of the specificity of the EIA/CA and the lack of independence of EIA/CA and TP-PA.

Conclusion: The Treponemal-First option costs slightly more and results in more unnecessary treatment.

MeSH terms

  • Algorithms*
  • Cost-Benefit Analysis
  • Humans
  • Mass Screening / economics*
  • Mass Screening / methods
  • Plasma / immunology
  • Reagins / blood
  • Sensitivity and Specificity
  • Syphilis / diagnosis*
  • Syphilis / drug therapy
  • Syphilis / economics*
  • Syphilis / epidemiology
  • Syphilis Serodiagnosis / economics*
  • Syphilis Serodiagnosis / methods
  • Treatment Outcome
  • Treponema pallidum / immunology
  • Treponema pallidum / isolation & purification*
  • United States / epidemiology


  • Reagins