ICD-10 Mortality Coding

The International Classification of Diseases has its origins in the preparation of mortality statistics. Death certificates are the main source of mortality data. Information on death certificates may be provided by either a medical practitioner or, in the case of accidents or violent deaths, a coroner. In some jurisdictions, another official (who may not be medically trained) is responsible for the completion of the medical certificate of cause of death.

The person certifying the cause of death will enter the sequence of events leading to the death on the death certificate using the international format. Information relating to the international form and the coding of reported conditions are available in volume 2 of ICD-10.


WHO recommends that, where practicable, a separate certificate should be used to record perinatal death. An international format is also recommended for this certificate.

Concept of underlying cause of death

Many death certificates give only a single cause of death. These are relatively simple to deal with ? the single cause reported is coded using the ICD-10.

However, in many other cases, two or more morbid conditions contribute to death. These should all be recorded on the certificate. In such cases it is the practice in vital statistics collections to select one of the causes of death for primary tabulation purposes. This single cause is usually referred to as the underlying cause of death. Whilst all other reported conditions may be coded, the concept of the underlying cause of death is central to mortality coding and comparable international mortality reporting.

WHO has defined the underlying cause of death as:

  • the disease or injury which initiated the train of morbid events leading directly to death; or
  • the circumstances of the accident or violence which produced the fatal injury.

Therefore, the underlying cause of death is the condition, event or circumstances without the occurrence of which the patient would not have died. For example, a person diagnosed with cancer dies and the immediate cause of death was heart failure resulting from carcinomatosis. However, the original neoplasm site was colon. The sequence would be malignant neoplasm resulting in carcinomatosis resulting in heart failure. In this example, the heart failure was the final morbid event in the sequence, starting with cancer of the colon. The malignant neoplasm of the colon is the condition to be coded as the underlying cause of death.

In recent years, the National Center for Health Statistics in the USA has developed the Mortality Medical Data System (MMDS) software to facilitate the coding of all causes of death reported on death certificates, and the designation of the underlying cause of death according to WHO criteria. Coding multiple causes of death is generally not possible without the support of coding software, such as the MMDS. Further information about the MMDS is available from http://www.cdc.gov/nchs/about/major/dvs/about.htm.

All coding of mortality data in Australia is the responsibility of the Health and Vitals Unit at the Australian Bureau of Statistics, Queensland office. The Australian Bureau of Statistics commenced use of the MMDS in 1997 and has available multiple cause of death data coded in ICD-10 for all years since that time. Prior to 1997, only underlying cause of death data is available.

The ABS has developed an internet bulletin board as a resource for coders and users of mortality data which has been processed using the MMDS. The intended purposes of the bulletin board are to provide a mechanism to post announcements and documents of interest, common questions and answers, and also to act as a mechanism whereby topics or questions can be discussed through discussion threads. The bulletin board is hosted and managed by the ABS but registration and submission of posts are open to anyone who registers. Access to the bulletin board is available by a userid (based on name) and password. Register to use this facility at http://www5.abs.gov.au/forums/icereg.nsf.

NCCH Brisbane provides coding, data management and project management expertise to the Australian Bureau of Statistics (ABS) through specific project work and educational opportunities for ABS staff.

The NCCH participated in the implementation of ICD-10 by the Health and Vitals National Project Centre, through the provision of education and training in ICD-10 for ABS staff. Introduction of the Medical Mortality Data System (MMDS) software used by the ABS was also achieved with the assistance from staff of the NCCH. The National Centre for Health Statistics has made the MMDS software available to the ABS.

NCCH Brisbane research staff assist researchers and data users in interpreting and understanding time series data spanning across different revisions of the ICD used for the coding of mortality data.

 

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