APPENDIX COMPARABILITY OF DATA OVER TIME
Comparability of mortality statistics over time is affected by a number of factors. These include issues relating to the collection, classification and processing of the data. In the late 1990s, there were two major changes within Australia; namely, the introduction of the tenth revision of the International Classification of Diseases (ICD-10) for classifying deaths registered from 1 January 1999 and the introduction of the Automated Coding System (ACS) for processing deaths registered from 1 January 1997.
A1.1 Introduction of Automated Coding and ICD-10
Prior to 1979, manual coding under relevant ICD revisions.
Comparability factors between manual and automated ICD-9 coding were produced, based on a sample of dual coded 1997 data.
1997 and 1998 data coded to ICD-10 following its introduction.
Comparability factors between ICD-9 (manually coded) and ICD-10 (automatically coded) based on 1997 backcoded data.
As a consequence of the coding of deaths registered in 1997 and 1998 to ICD-10 as well as ICD-9, there is now a single break in time series outlined in table A1.2.
A1.2 Time Series
To support this single break in series Table A1.3 provides concordances and comparability factors for all groupings in this publication. The concordance illustrates the conceptual differences between ICD-9 and ICD-10 classifications. The comparability factors are derived from the movements in the underlying causes of death coded in ICD-9 compared to ICD-10. Groupings with very small numbers have been annotated with an asterisk (*). Caution should be exercised when comparing the two versions of ICD for these groupings.
Additional concordance tables at the three and four digit level between records coded to ICD-9 and ICD-10 are available on request. Further information or clarification on the concordance between these revisions is available from the ABS on 1800 620 963.
COMPARISON OF NINTH AND TENTH REVISIONS OF ICD
The introduction of ICD-10 has resulted in changes to the interpretation and resultant coding of a number of causes, as outlined in the WHO publication International Statistical Classification of Diseases and Related Health Problems Tenth Revision, Volume 2. Causes most affected are Asthma, Mental and behavioural disorders and Diseases of the nervous system.
Under ICD-10, Asthma more clearly links with Chronic lower respiratory diseases, especially Bronchitis and Emphysema. Where these conditions are present, Chronic lower respiratory diseases takes precedence, resulting in a decrease in the reporting of asthma as the underlying cause.
The Chapters covering Mental and behavioural disorders and Diseases of the nervous system have undergone compensatory changes between ICD-9 and ICD-10 mainly due to Alzheimer's disease and certain dementias moving between these Chapters.
A1.3 Concordance and comparability factors
|Cause of Death |
|All causes |
|Chapter I Certain infectious and parasitic diseases |
|Human immunodeficiency virus (HIV) disease |
|Chapter II Neoplasms |
|Malignant neoplasms |
|Digestive organs |
|Rectosigmoid junction, rectum, anus and anal canal |
|Liver and intrahepatic bile ducts |
|Respiratory and intrathoracic organs |
|Trachea, bronchus and lung |
|Melanoma of skin |
|Female genital organs |
|Male genital organs |
|Urinary tract |
|Kidney, except renal pelvis |
|Eye, brain and other parts of central nervous system |
|Lymphoid, haematopoietic and related tissue |
|In situ and benign neoplasms and neoplasms of uncertain or unknown behaviour |
|Chapter III Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism |
|Chapter IV Endocrine, nutritional and metabolic diseases |
|Diabetes mellitus |
|Chapter V Mental and behavioural disorders |
|Psychoactive substance use |
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|Organic, including symptomatic, mental disorders |
|Chapter VI Diseases of the nervous system |
|Extrapyramidal and movement disorders |
|Alzheimer's disease |
|Chapter VII Diseases of the eye and adnexa |
|Chapter VIII Diseases of the ear and mastoid process |
|Chapter IX Disease of the circulatory system |
|All heart disease |
|Acute rheumatic fever and chronic rheumatic heart diseases |
|Hypertensive diseases |
|Ischaemic heart diseases |
|Acute myocardial infarction |
|Pulmonary heart disease and diseases of pulmonary circulation and other forms of heart disease |
|Cerebrovascular diseases |
|Diseases of arteries, arterioles and capillaries |
|Aortic aneurysm |
|Chapter X Diseases of the respiratory system |
|Influenza and pneumonia |
|Chronic lower respiratory diseases |
|Asthma and status asthmaticus |
|Chapter XI Diseases of the digestive system |
|Diseases of oesophagus, stomach and duodenum |
|Gastric and duodenal ulcer |
|Diseases of liver |
|Chapter XII Diseases of the skin and subcutaneous tissue |
|Chapter XIII Diseases of the musculoskeletal system and connective tissue |
|Arthropathies and systemic connective tissue disorders |
|Chapter XIV Diseases of the genitourinary system |
|Renal failure |
|Chapter XV Pregnancy, childbirth and the puerperium |
|Chapter XVI Certain conditions originating in the perinatal period |
|Disorders related to short gestation and low birthweight, not elsewhere classified |
|Infections specific to the perinatal period |
|Haemorrhagic and haematological disorders of fetus and newborn |
|Chapter XVII Congenital malformations, deformations and chromosomal abnormalities |
|Congenital malformations of the nervous system |
|Congenital malformations of the circulatory system |
|Congenital malformations of the respiratory system |
|Chapter XVIII Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified |
|Sudden infant death syndrome |
|Chapter XX External causes of morbidity and mortality |
|Transport accidents |
|Accidental drowning and submersion |
|Intentional self-harm |
|Hanging, strangulation and suffocation |