Promedas : A clinical diagnosticdecisionsupport system
Promedasis a medicalpatient-specific clinical diagnostic decision support systemsbasedon graphicalprobabilistic models.Promedasaimsto improve the quality andefficiency of the diagnosticprocess,while reducingits costs at thesametime. Modern-daymedicaldiagnosisis averycomplex process,requiring accuratepatient data, a profoundunderstandingof themedicalliteratureand many yearsof clinical experience.Diagnosisis a process, by whichadoctorsearchesfor thecause (disease)that best explains the symptomsof a patient. The searchprocessis sequential,in the sensethatpatientsymptomssuggestsomeinitial teststo be performed.Basedon the outcomeof thesetests,a tentati ve hypothesisis formulated about the possiblecause(s). Basedon this hypothesis,subsequent testsareorderedto confirm or reject this hypothesis.The processmay proceedin several iterationsuntil the patient is finally diagnosedwith sufficient certaintyandthe causeof thesymptomsis established. A significant part of the diagnosticprocessis standardizedin theform of protocols.Theseare setsof rules that prescribewhich teststo perform and in which order, basedon the patient symptomsandprevious testresults.Theserules form a decisiontree, whosenodesare intermediatestagesin thediagnosticprocessandwhose branchespoint to additional testing, depending on thecurrenttestresults.Theprotocolsaredefinedin eachcountryby a committeeof medical experts. In themayorityof thediagnosesthatareencountered,the guidelinesaresufficiently accurateto make the correctdiagnosis. For these’routine’ cases,a decisionsupportsystemis not needed. In 10-20% of the cases,however, the diagostic processis moredifficult. As a resultof the uncertaintyabout the correctdiagnosisand about the next actionsto perform, the decisionsmade by differentphysiciansat differentstagesof the diagnosticprocessdo not alwaysagreeandlack “rationalization”. In thesecases,normallya collegueis consultedthat is particularlyspecialized in this diseaseor the literatureis consulted.For thesedifficult casescomputerbaseddecisionsupport is of addedvalue. Since1996, we are developing a clinical diagnosticdecisionsupportsystem(CDDSS),called Promedas.The CDDSSis a computerprogram thatcontainsall relevantknowledgeabouta certain medical(sub)domainand generatespatient specificdiagnosticadvicein theform of a list of likely diagnosesand suggestionsfor additional laboratoryteststhat are expectedto be particularly informative to establishor rule out any of thediagnosesconsidered. Promedasis basedonmedicalexpertknowledge, acquiredfrom the medical literature and textbooksby the medicalspecialistsin our project team. In order to obtain a clinically relevant model it is crucial that the modelingis doneby the medicalexpertsthemselves. The domainof internalmedicineconsistsof many sub-domains (diabetes,lipids, endocrinology, etc.) and only specialistswith a specific specializationin the sub-domainareable to do suchmodelingaccurately. Theexpertknowledgeis storedin a database,in suchawaythatextensionandmaintenanceof the expertknowledgeis easilyfacilitated.