SPINEVolume31,Number18,pp2115–2123©2006,LippincottWilliams&Wilkins,Inc.AGoldStandardEvaluationofthe“DiscogenicPain”DiagnosisasDeterminedbyProvocativeDiscographyEugeneJ.Carragee,MD,ToddLincoln,MD,VikSinghParmar,MD,andToddAlamin,MDStudyDesign.Thisisaprospectivestudyofthevalid-ityofapositivetestresultinprovocativelumbardiscog-raphyforthediagnosisof“discogenicpain.”Objective.Toinvestigatethehypothesisthatprovoc-ativediscographybystrictcriteriaaccuratelyidentifiesalowbackpainillnessduetoaprimarydisclesion.SummaryandBackgroundData.AccordingtotheSackettandHaynescriteriaforestablishingdiagnostictestvalidity,notestwithoutagoldstandardexternalstandardcanbemeaningfullyapplied.Provocativedis-cographyasatestfordetermining“discogenicpain”has,todate,notbeencomparedagainstagoldstandard.Ab-sentagoldstandardreference,therecanbenovalidityassessmentorsystematicimprovementoftestaccuracy.Thisisthefirststudytoapplyanexternalgoldstandardevaluationofthediagnosticvalidityofdiscographyinanymanner.Methods.Overa5-yearperiodusingastrictenroll-mentprotocol,32patientswithlowbackpainandapos-itivesingle-levellow-pressureprovocativediscogram,underwentspinalfusion.Subjectswithknownpatientselectioncomorbiditieswereexcluded.Genericsurgicallimitations/morbiditywerecontrolledbycomparisontotheclinicaloutcomesofastrictly-matchedcohortof34patientshavingawell-acceptedsingle-levellumbarpa-thology(unstablespondylolisthesis).Treatmentsuccesswascomparedbetweengroups.Results.Inthecontrol-spondylolisthesisgroup,23of32patients(72%)metthehighlyeffectivesuccesscriteriacomparedwith8of30inthepresumeddiscogenicpaincohort(27%).Theproportionofpatientswhometthe“minimalacceptableoutcome”was29of32(91%)inthespondylolisthesisgroupand13of30(43%)inthepre-sumeddiscogenicpaingroup.Adjustingforsurgicalmor-bidityanddropoutfailure,byeithercriteriaofsuccess,thebest-casepositivepredictivevalueofdiscographywascalculatedtobe50%to60%.Conclusions.Positivediscographywasnothighlypre-dictiveinidentifyingbonafideisolatedintradiscallesionsprimarilycausingchronicseriousLBPillnessinthisfirststudycomparingdiscographyresultstoagoldstandard.Keywords:diagnosticvalidity,discogenicpain,lowbackpain,discography,spinalfusion,unstablespon-dylolisthesis,surgicaloutcome,prospectivestudy.Spine2006;31:2115–2123Approximately300,000spinalfusionsareperformedintheUnitedStateseachyear.1Themostcontroversialsub-groupofthesespinalfusionsisthatperformedforsup-posed“discogenicpain,”whichisprimarilydiagnosedbyprovocativediscography.Inthistest,thenucleusofadiscsuspectedofcausingapatient’sseverelowbackpain(LBP)illnessisinjected.Ifthisprovocationdemonstratesanulardisruptionandreproducesthepatient’susualLBP,thisisusuallyconsideredapositivetest,confirmingthatthediscperseisthecauseofthepatient’sLBPillness,independentofanypsychosocialorstructuralco-morbidity.However,thevalidityofprovocativediscog-raphyasadiagnostictestinevaluatingchronicLBPill-nessremainsunproven.Acriticaltestofvalidityforanydiagnosticprocedureinvolvesdirectlyassessingthetestresultsagainstagoldstandardinaclinicallyrelevantsetting(PhaseI–IIIstud-iesbytheSackettandHaynescriteria2).Forprovocativediscography,despitemanyproponents,nosuchstudieshaveyetbeenpublished.Norhaveproponentssuggestedareasonablegoldstandardagainstwhichtotestwhethertheresultsofdiscographyactuallyidentifyaclinicallyrelevantlesionprim...
