Coding and Classification

1. Coding and Classification Lection 2 Associated professor AndriySemenets semenets@tdmu.edu.te.uaDepartment of Medical InformaticsI.Ya.HorbachevskyTernopil State Medical University

2. Basic Questions • Introduction to classification • Classification basics • Medical Classification Systems

3. Important References • HANDBOOK of MEDICAL INFORMATICS. (Editors: J.H. van Bemmel, Erasmus University, Rotterdam):http://biophys.odmu.edu.ua/bmi/handbook/r_3_3/handbook/home.htm • Book:Handbookof Biomedical Informaticshttp://en.wikipedia.org/wiki/Book:Handbook_of_Biomedical_Informatics

4. 1. Introduction to classification • In the traditional patient record, data are available in written format only, mainly as free text, but sometimes also as numeric data, such as laboratory test results. • Reconstructing the patient history from such a handwritten patient record by a clinician other than the original author is hindered by the fact that many medical terms are ill-defined and are perhaps even ambiguous.

5. 1. Introduction to classification Medical coding is the process of assigning standardized medical codes (numerical, mnemonic, etc.) to patient medical charts. This coded information is used to: • ensure of the insurance companies; • government organizations (Medicare, USA); • patients alike all receive accurate billing statements for medical services performed.

6. 1. Introduction to classification

7. 1. Introduction to classification

8. 1. Introduction to classification Advantages of coding medical data: • Data reduction • Standardized terminology • Enabling statistical overviews and research • Support of management and planning • Coupling with decision-support systems

9. 2. Classification basics • Classificationdefinftion • Purpose and concepts • Ordering Principles • Nomenclatures and Thesauri • Codes • Taxonomy • Nosology

10. 2.1. Classification definition Thetermclassifyinghastwodifferentmeanings: • theprocessofdesigninga classification; • thecodingordescriptionofanobjectbyusingcodesortermsthataredesignatorsoftheconceptsin a classification.

11. 2.1. Classification definition We will useonlythefirstmeaningofclassifying: • A classificationisanorderedsystemofconceptswithin a domain, withimplicitorexplicitorderingprinciples. • A classificationisbasedonpriorknowledgeandforms a keytotheextensionofknowledge

12. 2.2. Purpose and concepts The purposeof a classificationis: (example)tosupportthegenerationofhealthcarestatisticsortofacilitateresearch. • Examplesaretheclassificationofabnormalitiesofelectrocardiogramsordiagnosesofpatientsintodiseaseclasses.

13. 2.2. Purposeandconcepts

14. 2.2. Purpose and concepts • Concepts are ordered according to generic relations. • Generic relations are relations of the type "A is a kind of B," (for example, pneumonia is a kind of lung disease, where pneumonia represents the narrower concept and lung disease represents the broader concept).

15. 2.2. Purpose and concepts Classificationscontainconceptswithin a certaindomain. Thedomaincanbedefinedas: • The set of elements to which a variable or function is limited. • Any area of interest that might be modeled, e.g., to create an information system.

16. 2.2. Purpose and concepts • Examples of domains are reason for encounter, diagnosis, and medical procedure. • In this respect the International Classification of Diseases, 9th edition (ICD-9), is a classification of diagnoses. • A classification allows one to compare findings collected in different environments. • Classifying is done according to a single criterion: age; that is, age is used as a differentiating criterion

17. 2.3. Ordering Principles Inclassifyingdiseaseswedealwiththefollowingaspects, amongothers: • anatomiclocation, • etiology, • morphology, and • dysfunction. Eachoftheseaspectscanbeusedfor a differentordering. Suchanorderingthroughout a classificationiscalledanaxis.

18. 2.3. Ordering Principles • Multiaxialclassificationsuseseveralorderingssimultaneously. • IntheInternationalClassificationofPrimaryCare (ICPC),forinstance, thediagnosesareclassifiedalongtwoaxes, onefortheorgansystem (analphabeticcharacter) andoneforthecomponents. • ICPC hasprimarilybeendesignedforepidemiologicalpurposes.

19. 2.3. Ordering Principles • Oneoftheproblemsofuniformregistrationinhealthcareisthelackof a commonterminology • A thesaurusis a listoftermsusedfor a certainapplicationareaordomain. Examplesare a listofdiagnostictermsor a listoftermsforlaboratorytests. • Forpracticalusage, thesaurithatalsocontain a listofsynonymsforeachpreferredtermhavealsobeendeveloped.

20. 2.3. Ordering Principles • A restrictedsetofpreferredtermsusedwithinanorganizationfor a givenpurposeiscalled a controlledvocabulary. • In a nomenclature, codesareassignedtomedicalconcepts, andmedicalconceptscanbecombinedaccordingtospecificrulestoformmorecomplexconcepts. Thisleadsto a largenumberofpossiblecodecombinations.

21. 2.3. OrderingPrinciples • The difference between a classification system and a nomenclature is that in the former possible codes are predefined, whereas in the latter a user is free to combine codes for all aspects involved. • The retrieval of records for patients whose data fulfill certain classification codes from a large database is relatively easy; retrieving records for patients stored by using a nomenclature is more difficult because of the high degree of freedom, leading to very complex codes.

22. 2.3. Ordering Principles Example of a multilevel classification of medical procedures. The differentiating criteria are indicated between rectangles. The criteria for membership in each subclass are not adopted here.

23. 2.3. OrderingPrinciples: Summary • Terminology • Thesaurus • Classification • Vocabulary • Nomenclature • Coding System  list of terms  ordered terms/synonyms  member_of arrangement  definitions  composition rules  codes as designators

24. 2.3. Examples • In 1933, theNewYorkAcademyofMedicinestartedworkon a databaseofmedicalterms, theStandardClassifiedNomenclatureofDiseases. • TheAmericanMedicalAssociationcontinuedthisworkin 1961, andin 1965 theSystematicNomenclatureofPathology (SNOP)codingsystemwaspublishedbytheAmericanCollegeofPathologists. • SNOPformedthebasisforthedevelopmentoftheSystematizedNomenclatureofHumanandVeterinaryMedicine ( SNOMED),whichisanexampleofsuch a nomenclature.

25. 2.3. Examples • SNOMED-CT: Terminology, Thesaurus, Classification, Vocabulary, Nomenclature, Coding System • ICD-10: Terminology, (Thesaurus), Classification, Vocabulary, Nomenclature, Coding System

26. 2.4. The Codes Terminologyforcodingmeansthatthreebasicelementsareusedinthe so-calledsemantictriangle: (1) object, (2) concept, and (3) term. • Objects,alsocalledreferents, areparticularthingsinreality, andtheyareconcrete (e.g., thestomach), aswellasabstract (e.g., themind). • A conceptis a unitofthoughtformedbyusingthecommonpropertiesof a setofobjects (e.g., anorgan). • A termis a designationby a linguisticexpressionof a conceptoranobjectin a specificlanguage.

27. 2.4. The Codes

28. 2.4. The Codes • Codingistheprocessofassigninganindividualobjectorcaseto a class, orto a setofclassesinthecaseof a multiaxialclassification. • Inmostclassifications, classesaredesignatedbycodes. • Codingis, infact, interpretationoftheaspectsofanobject. • Example: coding genderMale = m Female = f

29. 2.4. The Codes Differenttypesofcodes included: • Numbercodesmaybeissuedsequentially. Thismeansthateachnewclasswillbegiventhenextunusednumber. Theadvantageisthatnewclassescaneasilybeadded. • Numberscouldbeissuedatrandomtoavoidany patient-specific informationishiddeninthecode. • Seriesofnumberscanbereservedforsetsofclasses. Issuingthistypeofnumberisonlyofusewith a fixedsetofclasses, thatis, whennoexpansionofthesetofclassesisexpected.

30. 2.4. The Codes A mnemonic codeisformedfromoneormorecharactersofitsrelatedclassrubric. • Advantages: thishelpsuserstomemorizecodes. • Disadvantages:forclassificationswithmanyclassesthismayleadeithertolongcodesorcodeswithnoresemblancetotheclassrubrics. • Usedforlimitedlistsofclasses. • Example -hospitaldepartmentsareoftenindicatedby a mnemoniccode:ENT - DepartmentofEar, Nose, Throat,CAR - Cardiology,OB-GYN - DepartmentofObstetricsandGynecology.

31. 2.4. The Codes Hierarchicalcodesareformedbyextendinganexistingcodewithoneormoreadditionalcharactersforeachadditionallevelofdetail. • A hierarchicalcodethusbearsinformationonthelevelofdetailoftherelatedclassandonthehierarchicalrelationwithitsparentclass. • Thiswayofcodingbearsresemblancetothestructureofhierarchicaldatabases. • Thisimpliesthatpatientdatacanberetrievedbyusinghierarchicalcodesat a certainlevel, evenwhensignificantextensionsormodificationsaremadeatlowerlevels. • AnexamplearethecodesusedinICD-9.

32. 2.4. The Codes Example of a Four-Digit Code Level in ICD-9 and the Five-Digit Code Level as Extended by the ICD-9-CM

33. 2.4. The Codes Juxtapositioncodesarecompositecodesconsistingofsegments. Eachsegmentprovides a characteristicoftheassociatedclass.foreachadditionallevelofdetail. • Application:in ICPC a diagnosticcodeisformedbyusing a codeconsistingofoneletterofthealphabet (a mnemoniccode), followedby a two-digitnumber. • Example:allcodeswiththecharacter "D" arerelatedtothetractusdigestivusandallcodesstartingwithan "N" describedisordersofthenervoussystem. • Intheexampleof ICPC, twoindependentcharacteristicsarecodedsimultaneously, andeachcharacteristichasitsownpositioninthecode.

34. 2.4. The Codes Example of aThe Two-Axial ICPC

35. 2.4. The Codes • Medical procedures can be classified with ordering principles: action, equipment, aim, and anatomical site. • The combination of 100 anatomical sites with 20 different actions, 10 different instruments, and 5 different purposes results in a classification system with a potential of a 100,000 classes and codes. • A way to cope with it is the use of a combination code. • By using a six-digit combination code consisting of four segments, with segments dedicated to action (2 digits), equipment (2 digits), aim (1 digit), and anatomical site (1 digit), respectively, a coding clerk has to distinguish only 135 codes, with which 100,000 combinations can be generated.

36. 2.4. The Codes • Invalueadditioncodesingeneralonlypowersof 2areusedas a representationof a dataitemorclass. • Aseveralcharacteristicscanbecoded. Butonlyonenumberinsteadof a segmentforeachcharacteristicisusedas a code. • Example:wecodethepresenceorabsenceofriskfactors, suchas: - 20 = 1 forsmoker/0 fornonsmoker, - 21 = 2 foroverweight/0 fornooverweight, - 22 = 4 forincreasedcholesterol/0 fornotincreasedcholesterol. • Byusingthecodes 1 to 7 wecansumallthethreeriskfactorsmentionedabove.

37. 2.5. The Taxonomy • Taxonomy is the theoretical study of classification, including its basic principles, procedures, and rules. • Taxonomy is concerned with classifications in general. • The term classificationis used for the end product of the design process.

38. 2.5. The Taxonomy Proposed cognitive taxonomy of medical errors.

39. 2.6. The Nosology • Nosology is usually defined as the science of the classification of diseases. • Nosology is usually distinguished from nosography, which is the science of the description of diseases. • Difference between the definition and the description of disease: A disease definitiongives only essential characteristics of the disease, whereas a description includes accidental characteristics.

40. 3. Medical Classification Systems • ICD - International Classification of Diseases • ICPC - International Classification of Primary Care • SNOMED - Systematized Nomenclature of Human and Veterinary • DRG - Diagnosis Related Groups • MeSH - Medical Subject Headings • ATC - Anatomic Therapeutic Chemical Code

41. The USA Medical Coding and Classification an organization structure flowchart

42. 3.1. ICD • ICD(International Classification of Diseases)is the archetypal coding system for patient record abstraction. • The first edition was published in 1900, and it is being revised at approximately 10-year intervals. • The most recent version is ICD-10, which was published in 1992. • Most present registration systems, however, are still based on ICD-9 or its modification, ICD-9-CM

43. 3.1. ICD • ICD consists of a core classification of three-digit codes, which are the minimum requirement for reporting mortality statistics to WHO. • An optional fourth digit provides an additional level of detail. • At all levels, the numbers 0 to 7 are used for further detail, whereas the number 8 is reserved for all other cases and the number 9 is reserved for unspecified coding.

44. 3.1. ICD • The basic ICD is meant to be used for coding diagnostic terms. • ICD-9as well as ICD-10 also contain a set of expansions for other families of medical terms. • The disease codes of both ICD-9 and ICD-10 are grouped into chapters. • Example:for tuberculosis the three-digit codes 010 to 018 are used in ICD-9, and the codes A16 to A19 are used in ICD-10. • The U.S. National Center for Health Statistics published a set of clinical modifications to ICD-9, (ICD-9-CM). It contains an extra level of detail where needed and alsoinclude a volume III on medical procedures.

45. 3.1. ICD Example of a Four-Digit Code Level in ICD-9 and the Five-Digit Code Level as Extended by the ICD-9-CM

46. 3.1. ICD Example of a ICD-9-CMcoding helper software

47. 3.2. ICPC • The World Organization of National Colleges, Academies and Academic Associations of General Practitioners/Family Physicians (WONCA) did not accept ICD-9, but came up with its own classification -ICPC - International Classification of Primary Care. • ICPC is a two-axis system.The first axis, primarily oriented toward body systems (the tracts), is coded by a letter, and the second axis, the component, is coded by two digits. The component axis contains seven code groups. • Example:the diagnosis pneumonia is coded R81 (R for respiratory tract and 81 for the diagnostic component).

48. 3.2. ICPC • ICPC is used to encode encounters structured according to the SOAP principle: • S for subjective information, e.g., complaints; O is for objective information, e.g., test and lab results; A is for assessment, e.g., diagnosis; and P is for plan, e.g., diagnostic tests, treatment, etc. • An a way to organize patient-oriented information is by disease episodes. ICPC can be used to organize the registration of a disease episode over time, from its onset to its resolution. A disease episode may include several encounters. Each problem in an encounter should be coded separately.

49. 3.2. ICPC Example of aThe Two-Axial ICPC

50. 3.3. SNOMED • SNOMED (Systematized Nomenclature of Human and Veterinary)was first published in 1975 and was revised in 1979. • SNOMED is also a multiaxial system. SNOMED II was a code with 7 axes, and SNOMED International has 11 axes or modules. Each of these axes forms a complete hierarchical classification system.