Classification and

Coding Systems

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

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

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

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

Nomenclatures

Preferred term is called a „descriptor”

Facts are labelled or „indexed”Descriptors have to cover all

relevant aspectsPreffered use: retriving cases and

processing data

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

ICPC - International Classification for Primary care (2)

Alphanumerical codes: three digitsICPC 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.

Reaon for EncounterD01 (abdominal pain)D10 (vomiting)

ProcessD31 (partial.examinantion,digest.syst)

DiagnosisD73 (Gastroentritis)

L11 (wristsympt./compl.)L15 (kneesympt/compl)

L41 (diagn. radiolog.,musculoskeletal syst.)L50 (medication,musculesceletl syst.)

L91 Osteoarthritis

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 simpleLevel of detail suffices only for very

general analyses