The Cerebrospinal Fluid TPPA for Neurosyphilis · PDF fileThe Cerebrospinal Fluid TPPA for...
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The Cerebrospinal Fluid TPPA for Neurosyphilis Diagnosis Christina Marra, Shelia Dunaway, Lauren Tantalo, Sharon Sahi, University of Washington, Seattle, WA, USA Christina M. Marra, MD [email protected] Phone: 206-897-5400 Fax: 206-897-5401 767 Background There is no single sensitive and speci2ic test for diagnosis of neurosyphilis (NS). While the cerebrospinal 2luid (CSF)-Venereal Disease Research Laboratory (VDRL) test is speci2ic, it lacks sensitivity. In contrast, the CSF-2luorescent treponemal antibody- absorption (FTA-ABS) test is sensitive, but lacks speci2icity. In addition, the CSF-FTA-ABS is not available in many areas. The CSF- Treponema pallidum particle agglutination assay (TPPA) is an alternative to the CSF-FTA-ABS, but little information is available regarding its diagnostic performance. A titer cut-off of ≥1:320 improves the NS diagnostic performance of the CSF-Treponema pallidum hemagglutination test (TPHA) (1,2), a treponemal test that is similar to the TPPA, but the NS diagnostic utility of a CSF- TPPA cut-off has not been determined. Methods Participants were HIV-infected and HIV-uninfected individuals enrolled in a study of CSF abnormalities in syphilis. Study eligibility criteria included clinical or serological evidence of syphilis, and assessment by the referring provider that the patient was at risk for neurosyphilis. Reasons for referral to the study included 1) neurological 2indings, particularly vision or hearing loss; 2) serum Rapid Plasma Reagin (RPR) titer > 1:32, or 3) in HIV-infected individuals, peripheral blood CD4+ T cell count < 350/ul. CSF-FTA-ABS and CSF-TPPA reactivity were determined in a research laboratory using standard methods for a convenience sample of 192 participants enriched for reactive CSF-VDRL (training dataset). CSF-TPPA titers were determined for CSF-TPPA reactive samples. Subsequently, CSF-FTA-ABS reactivity, CSF- TPPA reactivity, and for CSF-TPPA reactive samples, CSF-TPPA reactivity at a 1:320 dilution, were determined for all available samples from study participants enrolled after the last training sample was collected (n=337, validation dataset). CSF white blood cell (WBC) concentration and CSF-VDRL reactivity were determined in a hospital clinical laboratory. Personnel who conducted the CSF-FTA-ABS and CSF-TPPA tests were blinded to other clinical and laboratory 2indings. Differences in characteristics of study participants in the training compared to validation datasets were assessed by Chi-square or Mann Whitney U tests. Kappa statistic, sensitivity and speci2icity were calculated using standard formulas. Differences in sensitivity and speci2icity were estimated by two sample test of proportion using Stata version 11.2. P-values <0.05 were considered to be statistically signi2icant. References 1. Luger AF et al. Int J STD AIDS. 2000;11(4):224-34. 2. Levchik N et al. Sex Transm Dis. 2013;40(12):917-22. Results Compared to participants in the validation dataset, those in the training dataset were younger, were more likely to have CSF abnormalities and more likely to be treated for NS. Table 1. Par+cipant Characteris+cs Training Dataset, n=192 Valida+on Dataset, n=337 P-value Male 186 (97) 330 (98) NS HIV-infected 159 (83) 267 (79) NS Age 37 (32-43) 42 (32-48) .002 1/Serum RPR +ter 64 (32-256) 64 (16-128) NS Early syphilis 134 (70) 251 (75) NS Reac+ve CSF- VDRL 61 (32) 42 (13) <.001 >20 WBCs/ul CSF 69 (36) 54 (16) <.001 Vision or hearing loss 40 (22), n=183 80 (24) NS Treated for NS 106 (55) 106 (32) <.001 Results are expressed as number (n), percent (%) or median (IQR) Figure 1. Percent of samples with reactive CSF treponemal tests Results • Signi2icantly more training samples had reactive CSF-TPPA and signi2icantly more were reactive at a titer of 1:320 or greater • Agreement between the CSF-FTA-ABS and CSF-TPPA in the training dataset was good (kappa=0.68) and in the validation dataset was moderate (kappa=0.58) • Overall, speci2icity and sensitivity of the CSF-FTA-ABS, CSF- TPPA and CSF-TPPA ≥1:320 using CSF-VDRL reactivity as the gold standard was similar in the training and validation datasets • However, speci2icity was higher and sensitivity was lower in the validation dataset when vision or hearing loss was used as the gold standard Figure 2. Speci2icity and sensitivity of CSF tests for NS diagnosis in the training (light blue) and validation (dark blue) datasets Table 2. Specificity and Sensi+vity of CSF Tests for NS Diagnosis in the Combined Datasets NS = Reac+ve CSF-VDRL NS = Vision or Hearing Loss Specificity % (95% CI) Sensi+vity % (95% CI) Specificity % (95% CI) Sensi+vity % (95% CI) CSF-FTA-ABS 59 (55-64) 99 (97-100) 53 (48-58) 68 (60-77) CSF-TPPA 69 (65-74)* 95 (91-99) 61 (56-66)** 58 (49-66) CSF TPPA ≥ 1:320 89 (86-92) 67 (58-76) 82 (78-86) 34 (26-43) CSF-VDRL -- -- 86 (82-89) 36 (27-44) 95% CI, 95% confidence interval; *P=.003 compared to CSF-FTA-ABS; **P=0.02 compared to CSF-FTA-ABS Summary • We examined the diagnostic utility of three CSF treponemal tests for NS diagnosis using a laboratory and a clinical gold standard in two groups of participants who were enrolled in a study of CSF abnormalities in syphilis • A convenience sample enriched for NS (training dataset, n=192) • Successive individuals enrolled after the last participant enrolled in the training dataset, regardless of CSF or clinical abnormalities (validation dataset, n=337) • Diagnostic performance was similar in the two datasets using the laboratory gold standard, but differed in the two datasets when the clinical gold standard was used • Overall, the CSF-FTA-ABS and the CSF-TPPA had high diagnostic sensitivity for laboratory (95-99%) , but not clinically deOined neurosyphilis (53-61%). While diagnostic speciOicity was lower, the speciOicity of the CSF- TPPA (61-69%) was signiOicantly better than the CSF-FTA- ABS (53-59%), regardless of the gold standard • The diagnostic speciOicity of the CSF-VDRL and the CSF- TPPA ≥1:320 were high (82-86%) and were not signiOicantly different; diagnostic sensitivity was quite low for both (34-36%) • In the combined datasets, speci2icity of the CSF-TPPA was better than the CSF-FTA-ABS using laboratory and clinical NS de2initions; sensitivity did not differ between the two tests • The diagnostic speci2icity of CSF-TPPA ≥1:320 was comparable to the CSF-VDRL test using a clinical NS de2inition Results Financial Support This work was supported by NIH/NINDS NS34235.
Transcript of The Cerebrospinal Fluid TPPA for Neurosyphilis · PDF fileThe Cerebrospinal Fluid TPPA for...
The Cerebrospinal Fluid TPPA for Neurosyphilis Diagnosis Christina Marra, Shelia Dunaway, Lauren Tantalo, Sharon Sahi, University of Washington, Seattle, WA, USA
Christina M. Marra, MD [email protected] Phone: 206-897-5400 Fax: 206-897-5401
767
Background Thereisnosinglesensitiveandspeci2ictestfordiagnosisofneurosyphilis(NS).Whilethecerebrospinal2luid(CSF)-VenerealDiseaseResearchLaboratory(VDRL)testisspeci2ic,itlackssensitivity.Incontrast,theCSF-2luorescenttreponemalantibody-absorption(FTA-ABS)testissensitive,butlacksspeci2icity.Inaddition,theCSF-FTA-ABSisnotavailableinmanyareas.TheCSF-Treponemapallidumparticleagglutinationassay(TPPA)isanalternativetotheCSF-FTA-ABS,butlittleinformationisavailableregardingitsdiagnosticperformance.Atitercut-offof≥1:320improvestheNSdiagnosticperformanceoftheCSF-Treponemapallidumhemagglutinationtest(TPHA)(1,2),atreponemaltestthatissimilartotheTPPA,buttheNSdiagnosticutilityofaCSF-TPPAcut-offhasnotbeendetermined.
Methods ParticipantswereHIV-infectedandHIV-uninfectedindividualsenrolledinastudyofCSFabnormalitiesinsyphilis.Studyeligibilitycriteriaincludedclinicalorserologicalevidenceofsyphilis,andassessmentbythereferringproviderthatthepatientwasatriskforneurosyphilis.Reasonsforreferraltothestudyincluded1)neurological2indings,particularlyvisionorhearingloss;2)serumRapidPlasmaReagin(RPR)titer>1:32,or3)inHIV-infectedindividuals,peripheralbloodCD4+Tcellcount<350/ul.
CSF-FTA-ABSandCSF-TPPAreactivityweredeterminedinaresearchlaboratoryusingstandardmethodsforaconveniencesampleof192participantsenrichedforreactiveCSF-VDRL(trainingdataset).CSF-TPPAtitersweredeterminedforCSF-TPPAreactivesamples.Subsequently,CSF-FTA-ABSreactivity,CSF-TPPAreactivity,andforCSF-TPPAreactivesamples,CSF-TPPAreactivityata1:320dilution,weredeterminedforallavailablesamplesfromstudyparticipantsenrolledafterthelasttrainingsamplewascollected(n=337,validationdataset).CSFwhitebloodcell(WBC)concentrationandCSF-VDRLreactivityweredeterminedinahospitalclinicallaboratory.PersonnelwhoconductedtheCSF-FTA-ABSandCSF-TPPAtestswereblindedtootherclinicalandlaboratory2indings.
DifferencesincharacteristicsofstudyparticipantsinthetrainingcomparedtovalidationdatasetswereassessedbyChi-squareorMannWhitneyUtests.Kappastatistic,sensitivityandspeci2icitywerecalculatedusingstandardformulas.Differencesinsensitivityandspeci2icitywereestimatedbytwosampletestofproportionusingStataversion11.2.P-values<0.05wereconsideredtobestatisticallysigni2icant.
References 1.LugerAFetal.IntJSTDAIDS.2000;11(4):224-34.2.LevchikNetal.SexTransmDis.2013;40(12):917-22.
Results Comparedtoparticipantsinthevalidationdataset,thoseinthetrainingdatasetwereyounger,weremorelikelytohaveCSFabnormalitiesandmorelikelytobetreatedforNS.
Table1.Par+cipantCharacteris+csTraining
Dataset,n=192Valida+on
Dataset,n=337P-value
Male 186(97) 330(98) NSHIV-infected 159(83) 267(79) NSAge 37(32-43) 42(32-48) .0021/SerumRPR+ter
64(32-256) 64(16-128) NS
Earlysyphilis 134(70) 251(75) NSReac+veCSF-VDRL
61(32) 42(13) <.001
>20WBCs/ulCSF 69(36) 54(16) <.001Visionorhearingloss
40(22),n=183 80(24) NS
TreatedforNS 106(55) 106(32) <.001Resultsareexpressedasnumber(n),percent(%)ormedian(IQR)
Figure1.PercentofsampleswithreactiveCSFtreponemaltests
Results • Signi2icantlymoretrainingsampleshadreactiveCSF-TPPAandsigni2icantlymorewerereactiveatatiterof1:320orgreater
• AgreementbetweentheCSF-FTA-ABSandCSF-TPPAinthetrainingdatasetwasgood(kappa=0.68)andinthevalidationdatasetwasmoderate(kappa=0.58)
• Overall,speci2icityandsensitivityoftheCSF-FTA-ABS,CSF-TPPAandCSF-TPPA≥1:320usingCSF-VDRLreactivityasthegoldstandardwassimilarinthetrainingandvalidationdatasets
• However,speci2icitywashigherandsensitivitywaslowerinthevalidationdatasetwhenvisionorhearinglosswasusedasthegoldstandard
Figure2.Speci2icityandsensitivityofCSFtestsforNSdiagnosisinthetraining(lightblue)andvalidation(darkblue)datasets
Table2.SpecificityandSensi+vityofCSFTestsforNSDiagnosisintheCombinedDatasets
NS=Reac+veCSF-VDRL NS=VisionorHearingLossSpecificity%(95%CI)
Sensi+vity%(95%CI)
Specificity%(95%CI)
Sensi+vity%(95%CI)
CSF-FTA-ABS 59(55-64) 99(97-100) 53(48-58) 68(60-77)CSF-TPPA 69(65-74)* 95(91-99) 61(56-66)** 58(49-66)CSFTPPA≥1:320
89(86-92) 67(58-76) 82(78-86) 34(26-43)
CSF-VDRL -- -- 86(82-89) 36(27-44)95%CI,95%confidenceinterval;*P=.003comparedtoCSF-FTA-ABS;**P=0.02comparedtoCSF-FTA-ABS
Summary • WeexaminedthediagnosticutilityofthreeCSFtreponemaltestsforNSdiagnosisusingalaboratoryandaclinicalgoldstandardintwogroupsofparticipantswhowereenrolledinastudyofCSFabnormalitiesinsyphilis
• AconveniencesampleenrichedforNS(trainingdataset,n=192)
• Successiveindividualsenrolledafterthelastparticipantenrolledinthetrainingdataset,regardlessofCSForclinicalabnormalities(validationdataset,n=337)
• Diagnosticperformancewassimilarinthetwodatasetsusingthelaboratorygoldstandard,butdifferedinthetwodatasetswhentheclinicalgoldstandardwasused
• Overall,theCSF-FTA-ABSandtheCSF-TPPAhadhighdiagnosticsensitivityforlaboratory(95-99%),butnotclinicallydeOinedneurosyphilis(53-61%).WhilediagnosticspeciOicitywaslower,thespeciOicityoftheCSF-TPPA(61-69%)wassigniOicantlybetterthantheCSF-FTA-ABS(53-59%),regardlessofthegoldstandard
• ThediagnosticspeciOicityoftheCSF-VDRLandtheCSF-TPPA≥1:320werehigh(82-86%)andwerenotsigniOicantlydifferent;diagnosticsensitivitywasquitelowforboth(34-36%)
• Inthecombineddatasets,speci2icityoftheCSF-TPPAwasbetterthantheCSF-FTA-ABSusinglaboratoryandclinicalNSde2initions;sensitivitydidnotdifferbetweenthetwotests
• Thediagnosticspeci2icityofCSF-TPPA≥1:320wascomparabletotheCSF-VDRLtestusingaclinicalNSde2inition
Results
Financial Support ThisworkwassupportedbyNIH/NINDSNS34235.
