ICD-10 Morbidity Coding

Many WHO member states use the ICD-10 as published by the World Health Organisation for morbidity coding. Prior to 1948, the International Classification of Diseases was used only for mortality coding. With the sixth revision of ICD in 1948 came the recognition of its potential for morbidity coding. The sixth revision then became an expanded version that included codes for non-fatal conditions. This expansion has continued ever since ? there has been a steady increase in the number of categories for coding non-fatal conditions and other health-related circumstances with each successive revision of the ICD.

For the purposes of ICD, the term morbidity covers illness, injuries and reasons for contact with health services, including screening and preventive care. Coding usually relates to an episode of health care in a health institution but may also apply to surveys or other primary data collections.

Coding practice varies from establishment to establishment or health authority to health authority ? in some places, one diagnosis will be singled out for coding (single-condition coding) while in other places, all diagnoses will be coded for each episode of care (multi-condition coding). Section 4.4 of Volume 2 of ICD-10 concerns the rules and guidelines adopted by the World Health Assembly regarding the selection of a single cause or condition for routine tabulation from morbidity records. It also provides guidelines for the application of the rules and for coding of the condition selected for tabulation. The following is an excerpt from this section.

The condition to be used for single-condition morbidity analysis is the main condition treated or investigated during the relevant episode of health care. The main condition is defined as the condition, diagnosed at the end of the episode of health care, primarily responsible for the patient?s need for treatment or investigation. If there is more than one such condition, the one held most responsible for the greatest use of resources should be selected. If no diagnosis was made, the main symptom, abnormal finding or problem should be selected as the main condition?By limiting the analysis to a single condition for each episode, some available information may be lost. It is therefore recommended, where practicable, to carry out multiple condition coding and analysis to supplement the routine data.

Support for coders who use the ICD-10 for coding morbidity data is available from the World Health Organization Family of International Classifications Network. Contact details for WHO-FIC Network members are available from http://www.who.int/whosis/icd10/collabor.htm. This support includes responses to questions relating to code assignment, expertise in data collection and processing methods and reporting functions. Specific information regarding access to educational materials and trainers is available on the WHO-FIC Education committee http://www.cdc.gov/nchs/about/otheract/icd9/nacc_subgroup.htm. The Australian WHO-FIC collaborating centre is located at the Australian Institute of Health and Welfare.

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