Diagnostic accuracy of a point-of-care syphilis test when used among pregnant women in Bolivia

Abstract

Objective: To evaluate the performance of a point-of-care (POC) syphilis test when used in urban Bolivian maternity hospitals. Methods: We tested 8892 pregnant women for syphilis using the Abbott Determine Syphilis TP rapid POC test and rapid plasma reagin (RPR) in the laboratory of four large urban maternity hospitals where national statistics reported a syphilis prevalence of at least 3%. Sera were stored and transferred to the national reference laboratory (INLASA) where RPR testing was repeated. When the reference laboratory staff observed a positive RPR result, a Treponema pallidum particle agglutination assay (TPPA) was performed to confirm these findings. We calculated test performance characteristics for the POC test and hospital RPR using RPR performed at the reference laboratory confirmed by TPPA as the reference standard. Participants received treatment during their initial visit based on the POC test results. Results: The sensitivity, specificity, negative predictive value and positive predictive values of the POC syphilis test were: 91.8% (95% confidence intervals 88.4% to 94.5%), 98.5% (98.2% to 98.8%), 71.0% (66.6% to 75.2%), and 99.7% (99.5% to 99.8%), respectively. The RPR values were 75.7% (70.8% to 80.2%), 99.0% (98.9% to 99.3%), 76.9% (72.0% to 81.3%), and 99.0% (98.8% to 99.2%), respectively. Conclusion: The Abbott Determine Syphilis TP test proved to be more sensitive than routine RPR and had comparable specificity. POC testing may be a simple way to expand syphilis screening to clinics with no laboratory facilities, improve case detection, and facilitate treatment delivery.

Evaluation of seven rapid tests for syphilis available in Brazil using defibrinated plasma panels

“…Results consistent with those found in the present study (100.0%) were reported by Lien et al 16 Hernández-Trejo et al 17 and Siedner et al 18 Other authors reported low sensitivity values when using finger-prick, whole blood samples as 88.0%,18 91.8%,19 85.7%20 and 97.3% 21. A multicentre clinic-based study performed by Mabey et al 22 also found low sensitivity in Tanzania (59.6%), Brazil (88.5%), China (81.9%) and Haiti (72.5%) 22…”

Rapid tests for sexually transmitted infections (STIs): the way forward

“…21 Tests with reasonable performance characteristics which can be performed on whole blood were evaluated in field settings in Bolivia, Brazil, China, Haiti, Peru and Tanzania. [22][23][24] Mathematical models developed with data from the field site in Mwanza, Tanzania showed that the use of these rapid tests is costeffective, and has the potential to make a substantial impact in averting congenital syphilis in primary health care settings. 25 …”

Desempeño de una prueba rápida para el diagnóstico de sífilis en mujeres puérperas

“…En nuestro estudio fueron positivas las muestras que tenían desde una coloración débil hasta fuerte en la línea de testeo de acuerdo a las indicaciones del fabricante y la sensibilidad obtenida de 84% concuerda con lo aceptado por un estudio de pruebas rápidas de sífilis evaluados por la Organización Mundial de la Salud (OMS), que muestra como rango aceptable del 84 a 97% comparando las pruebas rápidas con el TPHA(17). En cuanto a la especificidad encontrada, de 88,78 % comparada con TPHA es también aceptable con respecto a lo publicado con la OMS, que prevé especificidades de 84% en adelante (17,18).Se han encontrado mejores desempeños como en un estudio realizado en Bolivia en el cual la sensibilidad y especificidad de las pruebas rápidas encontradas comparadas con TPHA fue de 97,6 y 97,3 en 8924 embarazadas, sin conocer status de estado inmunológico contra la sífilis (18). En cuanto a la distribución por edad se observa una mayor cantidad de casos positivos de sífilis entre mujeres de 13 y 30 años con un porcentaje mayor de puérperas adolescentes (19%) que mujeres entre 31 a 35 años (15%) y entre 36 y 40 años (11%)lo que también describe un estudio en adolescentes paraguayas (19).…”