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Challenges of Rapid Plasma Reagin Interpretation in Syphilis Screening in Uganda: Variability in Nontreponemal Results Between Different Laboratories.
Sex Transm Dis. 2018 12; 45(12):829-833.ST

Abstract

BACKGROUND

Syphilis is a cause of morbidity and mortality and is of particular concern in pregnancy in low-income countries because of the risks associated with maternal-fetal transmission. Ugandan national guidelines recommend a nontreponemal rapid plasma reagin (RPR) followed by treponemal testing for diagnosis of syphilis. The RPR test confirms a reactive specific treponemal test, or confirms serological "cure" with a 4-fold dilutional decrease; RPR is beset with technical and biological limitations, making accurate diagnosis and appropriate treatment problematic. The aim of this analysis was to compare performance of RPR testing in different laboratories.

METHODS

Stored, freeze-thawed sera from 215 participants were additionally tested for RPR and dilutional titer in 2 different reference laboratories. Discrepant results were tested at a third reference laboratory which served as a tie-breaker. Equivalence in RPR titer was defined as within 2-fold or less. All patients with reactive rapid tests were treated as per Ugandan National Guidelines.

RESULTS

Of 215 sera, 97 (45.1%) were RPR reactive in clinic laboratory A, 81 (37.7%) and 65 (30.2%) were RPR reactive in laboratories B and C, respectively. All reported positive in laboratory C were positive in laboratory B. Discrepant results were tested in laboratory D. χ Test was highly significant (P = <0.001) for difference between each dyad of laboratories (A and B, A and C, and B and C) RPR results. There were significant differences between RPR titers by paired t test and Wilcox rank test (P = <0.001); with up to a 3-fold difference between laboratories. Two one-sided test approach demonstrated nonequivalence. Agreement between laboratories B-D, and C-D: 48 (98.0%) of 49 and 34 (69.4%) of 49, respectively (P = <0.001). Laboratories B and D showed no significant difference and had equivalent RPR titers. Laboratories C and D had different titers (P = <0.001) and were not equivalent.

CONCLUSIONS

We found significant interlaboratory discrepant RPR results. A 3-fold difference in results is likely to be clinically significant and could result in undertreatment or overtreatment. These data demonstrate a key limitation of the RPR test and underline the urgent need for a more reproducible quantitative test than the current RPR for diagnosing and determining cure of syphilis.

Authors+Show Affiliations

No affiliation info availableInfectious Disease Institute, Kampala, Uganda.Infectious Disease Institute, Kampala, Uganda.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableSchool of Public Health, Makerere University, Kampala, Uganda.No affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

29944643

Citation

Hamill, Matthew M., et al. "Challenges of Rapid Plasma Reagin Interpretation in Syphilis Screening in Uganda: Variability in Nontreponemal Results Between Different Laboratories." Sexually Transmitted Diseases, vol. 45, no. 12, 2018, pp. 829-833.
Hamill MM, Mbazira KJ, Kiragga AN, et al. Challenges of Rapid Plasma Reagin Interpretation in Syphilis Screening in Uganda: Variability in Nontreponemal Results Between Different Laboratories. Sex Transm Dis. 2018;45(12):829-833.
Hamill, M. M., Mbazira, K. J., Kiragga, A. N., Gaydos, C. A., Jett-Goheen, M., Parkes-Ratanshi, R., Manabe, Y. C., Nakku-Joloba, E., & Rompalo, A. (2018). Challenges of Rapid Plasma Reagin Interpretation in Syphilis Screening in Uganda: Variability in Nontreponemal Results Between Different Laboratories. Sexually Transmitted Diseases, 45(12), 829-833. https://doi.org/10.1097/OLQ.0000000000000883
Hamill MM, et al. Challenges of Rapid Plasma Reagin Interpretation in Syphilis Screening in Uganda: Variability in Nontreponemal Results Between Different Laboratories. Sex Transm Dis. 2018;45(12):829-833. PubMed PMID: 29944643.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Challenges of Rapid Plasma Reagin Interpretation in Syphilis Screening in Uganda: Variability in Nontreponemal Results Between Different Laboratories. AU - Hamill,Matthew M, AU - Mbazira,Kimeze J, AU - Kiragga,Agnes N, AU - Gaydos,Charlotte A, AU - Jett-Goheen,Mary, AU - Parkes-Ratanshi,Rosalind, AU - Manabe,Yukari C, AU - Nakku-Joloba,Edith, AU - Rompalo,Anne, PY - 2018/6/27/pubmed PY - 2019/9/13/medline PY - 2018/6/27/entrez SP - 829 EP - 833 JF - Sexually transmitted diseases JO - Sex Transm Dis VL - 45 IS - 12 N2 - BACKGROUND: Syphilis is a cause of morbidity and mortality and is of particular concern in pregnancy in low-income countries because of the risks associated with maternal-fetal transmission. Ugandan national guidelines recommend a nontreponemal rapid plasma reagin (RPR) followed by treponemal testing for diagnosis of syphilis. The RPR test confirms a reactive specific treponemal test, or confirms serological "cure" with a 4-fold dilutional decrease; RPR is beset with technical and biological limitations, making accurate diagnosis and appropriate treatment problematic. The aim of this analysis was to compare performance of RPR testing in different laboratories. METHODS: Stored, freeze-thawed sera from 215 participants were additionally tested for RPR and dilutional titer in 2 different reference laboratories. Discrepant results were tested at a third reference laboratory which served as a tie-breaker. Equivalence in RPR titer was defined as within 2-fold or less. All patients with reactive rapid tests were treated as per Ugandan National Guidelines. RESULTS: Of 215 sera, 97 (45.1%) were RPR reactive in clinic laboratory A, 81 (37.7%) and 65 (30.2%) were RPR reactive in laboratories B and C, respectively. All reported positive in laboratory C were positive in laboratory B. Discrepant results were tested in laboratory D. χ Test was highly significant (P = <0.001) for difference between each dyad of laboratories (A and B, A and C, and B and C) RPR results. There were significant differences between RPR titers by paired t test and Wilcox rank test (P = <0.001); with up to a 3-fold difference between laboratories. Two one-sided test approach demonstrated nonequivalence. Agreement between laboratories B-D, and C-D: 48 (98.0%) of 49 and 34 (69.4%) of 49, respectively (P = <0.001). Laboratories B and D showed no significant difference and had equivalent RPR titers. Laboratories C and D had different titers (P = <0.001) and were not equivalent. CONCLUSIONS: We found significant interlaboratory discrepant RPR results. A 3-fold difference in results is likely to be clinically significant and could result in undertreatment or overtreatment. These data demonstrate a key limitation of the RPR test and underline the urgent need for a more reproducible quantitative test than the current RPR for diagnosing and determining cure of syphilis. SN - 1537-4521 UR - https://www.unboundmedicine.com/medline/citation/29944643/Challenges_of_Rapid_Plasma_Reagin_Interpretation_in_Syphilis_Screening_in_Uganda:_Variability_in_Nontreponemal_Results_Between_Different_Laboratories_ L2 - http://dx.doi.org/10.1097/OLQ.0000000000000883 DB - PRIME DP - Unbound Medicine ER -