APPENDIX 4 COMPARABILITY OF STATISTICS OVER TIME


INTRODUCTION

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 1990's, 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.

A4.1 Introduction of Automated Coding and ICD-10
Years	Coding Method	ICD revision		Comments
1979-1996	Manual	ICD-9		Prior to 1979, manual coding under relevant ICD revisions.
1997-1998	Automated	ICD-9		Comparability factors between manual and automated ICD-9 coding were produced, based on a sample of dual coded 1997 data.
1997-1998	Automated	ICD-10		1997 and 1998 data coded to ICD-10 following its introduction.
1999-	Automated	ICD-10 only		Comparability factors between ICD-9 (manually coded) and ICD-10 (automatically coded) based on 1997 backcoded data.

TIMES SERIES

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 A4.2.

A4.2 Time Series
Years	Coding method	ICD revision
1979-1996	Manual	ICD-9
1997-onwards	Automated	ICD-10

To support this single break in series table A4.3 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 National Information and Referral Service on 1300 135 070.


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.

A4.3 Concordance and comparability factors
Cause of Death				ICD-10 Code	ICD-9 Code	Comparability factor
All causes				A00-Y98	001-999	1.00
Chapter I Certain infectious and parasitic diseases				A00-B99	001-139	1.25
	Septicaemia			A40, A41	038	1.28
	Human immunodeficiency virus (HIV) disease			B20-B24	042-044	1.03
Chapter II Neoplasms				C00-D48	140-239	1.00
	Malignant neoplasms			C00-C97	140-208	1.00
		Digestive organs		C15-C26	150-157, 159	0.99
			Oesophagus	C15	150	1.00
			Stomach	C16	151	0.99
			Colon	C18	153	0.98
			Rectosigmoid junction, rectum, anus and anal canal	C19-C21	154	0.98
			Liver and intrahepatic bile ducts	C22	155	1.07
			Pancreas	C25	157	0.99
		Respiratory and intrathoracic organs		C30-C39	160-165	0.94
			Trachea, bronchus and lung	C33, C34	162	0.97
		Melanoma of skin		C43	172	0.98
		Breast		C50	174, 175	0.98
		Female genital organs		C51-C58	179-184	0.99
			Ovary	C56	1 830	0.98
		Male genital organs		C60-C63	185-187	0.99
			Prostate	C61	185	0.98
		Urinary tract		C64-C68	188, 189	0.96
			Kidney, except renal pelvis	C64	1 890	0.96
			Bladder	C67	188	0.95
		Eye, brain and other parts of central nervous system		C69-C72	190-192	0.97
			Brain	C71	191	0.97
		Lymphoid, haematopoietic and related tissue		C81-C96	200-208	0.97
			Leukaemia	C91-C95	204-208	0.94
	In situ and benign neoplasms and neoplasms of uncertain or unknown behaviour			D00-D48	210-239	1.18
Chapter III Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism				D50-D89	279, 280-289	1.07
Chapter IV Endocrine, nutritional and metabolic diseases				E00-E90	240-278	1.01
	Diabetes mellitus			E10-E14	250	0.99
Chapter V Mental and behavioural disorders				F00-F99	290-319	0.78
	Psychoactive substance use			F10-F19	291, 292	1.09
					303, 304, 305
	Organic, including symptomatic, mental disorders			F00-F09	290	0.69
Chapter VI Diseases of the nervous system				G00-G99	320-359	1.20
	Extrapyramidal and movement disorders			G20-G26	332-333	0.95
	Alzheimer's disease			G30	3 310	1.48
Chapter VII Diseases of the eye and adnexa				H00-H59	360-379	*
Chapter VIII Diseases of the ear and mastoid process				H60-H95	380-389	*
Chapter IX Disease of the circulatory system				I00-I99	390-459	1.00
	All heart disease			I05-I09, I11	393-398, 402	1.01
				I13, I20-I25	404, 410-414
				I26, I27	415, 416
				I30-I52	420-429
	Acute rheumatic fever and chronic rheumatic heart diseases			I00-I09	390-398	0.69
	Hypertensive diseases			I10-I15	401-405	1.00
	Ischaemic heart diseases			I20-I25	410-414	1.01
		Acute myocardial infarction		I21	410	0.96
	Pulmonary heart disease and diseases of pulmonary circulation and other forms of heart disease			I26-I52	415-429	1.06
	Cerebrovascular diseases			I60-I69	430-438	0.97
	Diseases of arteries, arterioles and capillaries			I70-I79	440-448	0.97
		Atherosclerosis		I70	440	0.98
		Aortic aneurysm		I71	441	0.97
Chapter X Diseases of the respiratory system				J00-J99	460-519	0.91
	Influenza and pneumonia			J10-J18	480-487	0.87
	Chronic lower respiratory diseases			J40-J47	490-496	0.91
		Emphysema		J43	492	0.86
		Asthma and status asthmaticus		J45, J46	493	0.75
Chapter XI Diseases of the digestive system				K00-K93	520-579	1.05
	Diseases of oesophagus, stomach and duodenum			K20-K31	530-537	1.04
		Gastric and duodenal ulcer		K25-K27	531-533	0.99
	Diseases of liver			K70-K77	570-573	1.02
Chapter XII Diseases of the skin and subcutaneous tissue				L00-L99	680-709	1.06
Chapter XIII Diseases of the musculoskeletal system and connective tissue				M00-M99	710-739	1.15
	Arthropathies and systemic connective tissue disorders			M00-M36	710-719	1.19
Chapter XIV Diseases of the genitourinary system				N00-N99	580-629	1.14
	Renal failure			N17-N19	584-586	1.05
Chapter XV Pregnancy, childbirth and the puerperium				O00-O99	630-676	*
Chapter XVI Certain conditions originating in the perinatal period				P00-P96	760-779	0.96
	Disorders related to short gestation and low birthweight, not elsewhere classified			P07	765	*
	Infections specific to the perinatal period			P35-P39	771	*
	Haemorrhagic and haematological disorders of fetus and newborn			P50-P61	772-774, 776	*
Chapter XVII Congenital malformations, deformations and chromosomal abnormalities				Q00-Q99	740-759	1.03
	Congenital malformations of the nervous system			Q00-Q07	740-742	1.00
	Congenital malformations of the circulatory system			Q20-Q28	745-747	1.12
	Congenital malformations of the respiratory system			Q30-Q34	748	0.90
Chapter XVIII Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified				R00-R99	780-799	0.76
	Sudden infant death syndrome			R95	7 980	0.94
Chapter XX External causes of morbidity and mortality				V01-Y98	E800-E999	1.06
	Accidents			V01-X59	E800-E949	1.05
		Transport accidents		V01-V99	E800-E848	1.03
		Falls		W00-W19	E880-E886, E888	1.10
		Accidental drowning and submersion		W65-W74	E910	1.03
	Intentional self-harm			X60-X84	E950-E959	0.97
		Hanging, strangulation and suffocation		X70	E953	0.97
	Assault			X85-Y09	E960-E969	1.02