Background Diagnosis of congenital syphilis (CS) is not straightforward and can be challenging. This study aimed to evaluate the validity of an algorithm using timing of maternal antisyphilis treatment and titres of non-treponemal antibody as predictors of CS.
Methods Confirmed CS cases and those where CS was excluded were obtained from the Guangzhou Prevention of Mother-to-Child Transmission of syphilis programme between 2011 and 2019. We calculated sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) using receiver operating characteristics (ROC) in two situations: (1) receiving antisyphilis treatment or no-treatment during pregnancy and (2) initiating treatment before 28 gestational weeks (GWs), initiating after 28 GWs or receiving no treatment for syphilis seropositive women.
Results Among 1558 syphilis-exposed children, 39 had confirmed CS. Area under the curve, sensitivity and specificity of maternal non-treponemal titres before treatment and treatment during pregnancy were 0.80, 76.9%, 78.7% and 0.79, 69.2%, 88.7%, respectively, for children with CS. For the algorithm, ROC results showed that PPV and NPV for predicting CS were 37.3% and 96.4% (non-treponemal titres cut-off value 1:8 and no antisyphilis treatment), 9.4% and 100% (non-treponemal titres cut-off value 1:16 and treatment after 28 GWs), 4.2% and 99.5% (non-treponemal titres cut-off value 1:32 and treatment before 28 GWs), respectively.
Conclusions An algorithm using maternal non-treponemal titres and timing of treatment during pregnancy could be an effective strategy to diagnose or rule out CS, especially when the rate of loss to follow-up is high or there are no straightforward diagnostic tools.
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S-FL and SZ contributed equally.
Contributors FH conceived the study, provided funding and drafted manuscript. J-JL and S-JG revised the paper. Y-YS and N-XH coordinated and supervised data collection. S-FL and SZ conceived the study. All authors were involved in the data interpretation and contributed to drafting and revision of the paper. All authors read and approved the final manuscript.
Funding The project was supported by The AbbVie Foundation for Maternity and Child Care and Prevention of Mother-to-child Transmission Chinese Association of STD and AIDS Prevention and Control (2020PMTCT-S6) and Guangzhou Institute of Pediatrics/Guangzhou Women and Children’s Medical Center (YIP-2019-001).
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval This study was approved by the Ethics Approval Board of Guangzhou Women and Children’s Medical Center (202046801).
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