1. Classification andCoding Systems

2. Overview • Why doctors are using coding systems? • What is a coding system? • Short introduction of: • ICD-9 and ICD-9 CM • ICD-10 • ICPC • SNOMED International

3. Why Coding Systems? (1) • Elements of Coding Systems: • controlled vocabularies to avoid syntactical variations • concept systems to porvide semantic relations • codes reflecting the hierarchy of concept systems Everythig to avoid problems with free-text data

4. Why Coding Systems? (2) • Problems with free-text data elements: • Retriving cases lexical variants, synonyms, no hierarchy • Grouping cases for counting and averaging • Assuring data quality • Using data as input to further processing

5. Classifications • Concepts are called „classes”;the concept’s preferred term is the class name • Facts are fitted into a category, or classified (and then: encoded) • Classes are complete and pair-wise disjunctive • Preferred use: counting and averaging

6. Nomenclatures • Preferred term is called a „descriptor” • Facts are labelled or „indexed” • Descriptors have to cover all relevant aspects • Preffered use: retriving cases and processing data

7. ICPC - International Classification for Primary care (1) • A manageable coding systems to enable • population based health studies • systematic analysis of the care process • A three-dimensional, non-hierarchic classification: • reason for encounter • diagnosis or problem • care process • 17 chapters for the body systems with identical structure

8. Alphanumerical codes: three digits ICPC sample notation: 60 y/o male patien presents with vomiting and abdominal pain. He also complains of pain in both knees, his left wrist and some visible swelling, for which he seeks attention. ICPC - International Classification for Primary care (2)

9. ICPC: Applications and Limitations • Made to analyse the care process in general and family medicine • Takes into account the patient’s motivation • Is very systematic and simple • Level of detail suffices only for very general analyses