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Death Certificates and Coding the Causes of Death

This section describes briefly how causes of death are recorded on death certificates, and provides links to examples of the medical certificate of the cause of death and the guidance which is given to doctors. This section then mentions the bases on which figures can be produced, and indicates how the causes of death are coded.

The medical certificate of the cause of death

The medical certificate of the cause of death is completed by a registered medical practitioner. It has two parts:

Part 1

Should show the immediate cause of death, and then work back in time to the disease or condition that started the process. It should therefore identify:

• the disease or condition that led directly to the death;
• any antecedent or intermediate causes of that disease or condition (i.e. which occurred earlier in the chain of events that led to the death); and, eventually, going back to -
• the underlying cause of death - this is defined (on pages 33-34 of Volume 2 of the International Standard Classification of Diseases and Related Health Problems) as:
  “(a) the disease or injury which initiated the chain of morbid events leading directly to death or (b) the circumstances of the accident or violence which produced the fatal injury". 

For example:

• the disease or condition that led directly to death might be a compound fracture of the skull or a ruptured liver; 
• whereas the underlying cause of death might be a gunshot wound, or being injured in a road accident.

Part 2

Can be used to record other significant diseases, conditions or accidents which contributed to the occurrence of the death, but were not part of the main sequence leading to the death. However, Part 2 should not be used to list all the conditions that were present at death.

For example:

• a person with diabetes who died of lung cancer might have died sooner than would have been the case if he/she did not have diabetes - if so, diabetes should be recorded as contributing to the death; but
• if the person also had osteoarthiritis, it is unlikely that it would have contributed to the death, so it should not be mentioned in Part 2.

The medical practitioner is required to certify the cause or causes of death to the best of his/her knowledge and belief.  While the information that is recorded is a matter for the doctor's clinical judgment, guidance is provided, with the aim of achieving a consistent approach to death certification across Scotland.  This includes advice on points that should be covered and how particular causes should be reported, and examples of the kinds of terminology that should (or should not) be used.

The medical certificate of the cause of death and the notes of guidance have changed over the years, as can be seen from the examples below:

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• Current Guidance on Completion of Medical Certificates of the Cause of Death, issued by the Chief Medical Officer for Scotland - September 2009 (hosted on the Scottish Government Health Directorates website)
• Current Medical Certificate of the Cause of Death, and the accompanying guidance which was issued by GROS in January 1999
• The Medical Certificate of the Cause of Death used from April 1990 to December 1998, and accompanying guidance which was issued by GROS in April 1990
• The Medical Certificate of the Cause of Death, and accompanying guidance used from January 1966 to March 1990, and accompanying guidance issued by GROS in January 1966

The bases on which figures can be produced

As a result, figures for a particular cause of death can be produced on three bases:

• "underlying cause" - cases where it was the disease or injury which initiated the chain of morbid events leading directly to death, or was the accident/act which produced the fatal injury;  
• "contributory factor" - cases where it was not the underlying cause of death, but it did contribute to the occurrence of the death - e.g. it did not cause the death, but may have hastened its occurrence
• "any mention" - i.e. whether it appeared to be the underlying cause of the death, or was just a factor which contributed to, or may have hastened, the occurrence of the death.

Figures are normally provided on the basis of the "underlying cause". Every death has just one "underlying cause" code, and so is counted only once in figures which are produced on the "underlying cause" basis.

A death may have several other causes coded as contributory factors, so could be counted several times in figures which are produced on the "contributory factor" or "any mention" bases. For that reason, figures are normally provided on the basis of the "underlying cause".

Coding the causes of death

For deaths registered from 1 January 2000, the causes of death have been coded in accordance with the International Statistical Classification of Diseases and Related Health Problems (Tenth Revision), which may be referred to as "ICD10". Deaths which were registered in 1999 were coded using both ICD9 and ICD10, in order to obtain an indication of the effect on the figures of the change in the classification. The definitive figures for 1999 are those produced using ICD9. 

The classification of the underlying cause of death is based on the information collected on the death certificate together with any additional information provided by other official sources - for more on this, see the page on Sources of information for coding the causes of death. 

The application of the ICD10 rules can lead to the underlying cause being coded to something other than the final entry in Part 1 of the death certificate - for example:

• if this is something which is "ill-defined" for ICD purposes (e.g. "organ failure"), in which case a more specific cause of death is coded, if one is available;
• if it is an obvious consequence of one or more of the other conditions which were reported (either in Part 1 or Part 2) - e.g. "any disease described as secondary should be assumed to be a consequence of the most probably primary cause entered on the certificate";
• if it is "linked by a provision in the classification or in the notes for underlying cause mortality coding with one or more of the other conditions on the certificate", in which case the appropriate combination is coded.

In January 1996, the General Register Office for Scotland introduced an automated method of coding the causes of death, using software provided by the United States National Centre for Health Statistics. While this handles "straightforward" cases correctly, experienced coding staff are still needed to check the results and to code the more complicated cases.

Further information about coding and classifying causes of death is available in the Annex to Chapter 2 of "Scotland's Population 2005".