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


CONCLUSIONS
The Treponemal-First option costs slightly more and results in more unnecessary treatment.
Owusu-Edusei
Kwame
K
Division of STD Prevention, Centers for Disease Control and Prevention, 1600 Clifton Road MS E-80, Atlanta, GA 30333, USA. kowusuedusei@cdc.gov
Peterman
Thomas A
TA
Ballard
Ronald C
RC
D000465:Algorithms; D003362:Cost-Benefit Analysis; D006801:Humans; D008403:Mass Screening / Q000191:economics* / Q000379:methods; D010949:Plasma / Q000276:immunology; D011935:Reagins / Q000097:blood; D012680:Sensitivity and Specificity; D013587:Syphilis / Q000175:diagnosis* / Q000188:drug therapy / Q000191:economics* / Q000453:epidemiology; D013588:Syphilis Serodiagnosis / Q000191:economics* / Q000379:methods; D016896:Treatment Outcome; D014210:Treponema pallidum / Q000276:immunology / Q000302:isolation & purification*; D014481:United States / Q000453:epidemiology
D011935:Reagins