Impact of the dual rapid diagnostic test for HIV and syphilis among pregnant women: a before and after health center-based study in Central Uganda (2018-2019)

Background: Systematic testing of antenatal clinic attendees using dual HIV and syphilis rapid diagnostic tests (RDT) can improve syphilis testing and reduce mother-to-child transmission. We assessed the effect of the dual HIV/syphilis RDT on syphilis care and adverse birth outcomes, including congenital syphilis in Central Uganda.

Methods: Eleven antenatal clinics were selected from Kalungu and Masaka districts. First-visit records were extracted on syphilis testing, positivity and treatment over two 9-month periods, pre- and post-introduction, with a 3-month buffer. Syphilis cascade indicators were calculated for the two periods. The WHO Congenital Syphilis Estimation Tool evaluated impact on congenital syphilis cases and adverse birth outcomes.

Results: 6,011 records were extracted, 2,660 pre-test introduction and 3,351 post-introduction. Syphilis testing increased from 49·1% pre-test to 84·0% post-introduction, an increased testing rate ratio of 1·71 ([95% Confidence Interval] 1·64-1·78). Treatment coverage modestly increased post-introduction (rate ratio=1·19, 0·94-1·50) resulting in an absolute rate difference of 31·4% (20·5%-41·6%, p<0.001). This resulted in a modelled 41% decline in congenital syphilis cases and 39% decline in adverse birth outcomes.

Conclusions: This is the first demonstration of the impact of dual HIV/syphilis RDT in routine antenatal clinics in Uganda, which could reduce congenital syphilis and adverse birth outcomes.