Improving global estimates of syphilis in pregnancy by diagnostic test type: A systematic review and meta-analysis

Abstract

Background: "Probable active syphilis," is defined as seroreactivity in both non-treponemal and treponemal tests. A correction factor of 65%, namely the proportion of pregnant women reactive in one syphilis test type that were likely reactive in the second, was applied to reported syphilis seropositivity data reported to WHO for global estimates of syphilis during pregnancy.

Objectives: To identify more accurate correction factors based on test type reported.

Search strategy: Medline search using: "Syphilis [Mesh] and Pregnancy [Mesh]," "Syphilis [Mesh] and Prenatal Diagnosis [Mesh]," and "Syphilis [Mesh] and Antenatal [Keyword].

Selection criteria: Eligible studies must have reported results for pregnant or puerperal women for both non-treponemal and treponemal serology.

Data collection and analysis: We manually calculated the crude percent estimates of subjects with both reactive treponemal and reactive non-treponemal tests among subjects with reactive treponemal and among subjects with reactive non-treponemal tests. We summarized the percent estimates using random effects models.

Main results: Countries reporting both reactive non-treponemal and reactive treponemal testing required no correction factor. Countries reporting non-treponemal testing or treponemal testing alone required a correction factor of 52.2% and 53.6%, respectively. Countries not reporting test type required a correction factor of 68.6%.

Conclusions: Future estimates should adjust reported maternal syphilis seropositivity by test type to ensure accuracy.

Keywords: Congenital syphilis; Diagnostics; Pregnancy; Prenatal diagnosis; Syphilis.

Fig. 1

Flow diagram of study selection.

Fig. 2

Meta-analysis of studies reporting non-treponemal (NT) and treponemal (TP) test results in pregnant women and correction factor estimates for the WHO reporting Categories 2 and 3 with 95% CIs. *Points represent reported study values for given Category; bars represent 95% CIs. EIA, Enzyme immunoassay; FTA-Abs, Fluorescent treponemal antibody absorption; RPR, Rapid plasma regain; TPHA, T. pallidum hemagglutination assay; TP, Treponema pallidum; VDRL, Venereal disease research laboratory.