1. Classification and Coding Systems

2. Overview zWhy doctors are using coding systems? zWhat is a coding system? zShort introduction of: yICD-9 and ICD-9 CM yICD-10 yICPC ySNOMED International

3. Why Coding Systems? (1) zElements of Coding Systems: ycontrolled vocabularies to avoid syntactical variations yconcept systems to porvide semantic relations ycodes reflecting the hierarchy of concept systems Everythig to avoid problems with free-text data

4. Why Coding Systems? (2) zProblems with free-text data elements: yRetriving cases lexical variants, synonyms, no hierarchy yGrouping cases for counting and averaging yAssuring data quality yUsing data as input to further processing

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

6. Nomenclatures zPreferred term is called a „descriptor” zFacts are labelled or „indexed” zDescriptors have to cover all relevant aspects zPreffered use: retriving cases and processing data

7. ICPC - International Classification for Primary care (1) zA manageable coding systems to enable ypopulation based health studies ysystematic analysis of the care process zA three-dimensional, non-hierarchic classification: yreason for encounter ydiagnosis or problem ycare process z17 chapters for the body systems with identical structure

8. ICPC - International Classification for Primary care (2) zAlphanumerical codes: three digits zICPC 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.

9. ICPC: Applications and Limitations zMade to analyse the care process in general and family medicine zTakes into account the patient’s motivation zIs very systematic and simple zLevel of detail suffices only for very general analyses