Coding mortality data

Coding mortality data Cleo Rooney Office for National Statistics London, England

Uses of Mortality statistics • Public health • Identifying health priorities • formulating health policy • evaluating effectiveness of policies and interventions • Epidemiology • identifying risk factors for diseases and death • comparing risk by population group

Comparability of data • over time • between coders, within • between areas within the country • between countries • between population groups • age, sex, ethnic origin • between deaths in different settings • public / private hospital, at home, urban and rural

Comparability of data depends on • Data collection • data processing • including coding • analysis • interpretation

Items to be coded • Sex, age / age group • Geography - area of residence, area of death • marital status • occupation, employment status • ?socio-economic class, education • ?country of birth, ethnic group, nationality • Cause of death

Data Collection • Death certification • certificate of cause of death • certifiers • Death registration • who supplies other information? • Family, hospital, funeral director? • Completeness of registration • avoid bias • describe mortality of whole population

Prerequisites • Vital Registration system • ‘Medical’ certification of cause of death • cause of death coders trained in • manual ICD coding or • automated ICD coding

Vital registration • UN guidelines • registration of births, deaths, marriages • Complete • Timely • Good quality

Quality assurance • Completeness • ? External check, eg records of burials, cremations • legal necessity to dispose of body or prove will / inheritance • Timeliness • from death to registration • to coding , analysis and publication

Certifying the cause of death • Who certifies cause? • General practitioner, hospital clinician, pathologist, public health doctor, forensic specialist, coroner • Other? • How are they trained? • Undergraduate, post-graduate, practical experience • who trains them? • Is there an examination or qualification?

Checks on certified cause of death • Validity by Age, sex and cause • One certifier or two? • Comparisons • back to medical or laboratory records • back to family or other witnesses • to post-mortem findings • all or a sample of deaths?

Underlying cause of death • Most mortality statistics are based on ‘underlying cause’ • WHO defines as • …’the disease or [external cause of] injury which initiated the train of morbid events leading directly to death….’ • For public health • preventing death and illness leading to death

World Heath Assembly... “..members shall adopt a form of medical certificate of cause of death that provides for the statement of the morbid conditions or injuries resulting in or contributing to death, with a clear indication of the underlying cause.” Article 5 of the the 1967 WHO Nomenclature Regulations, adopted by The Twentieth World Health Assembly, on 22 of May 1967.

Selecting The UCD in ICD-10 General Principle “When one or more conditions is entered on the certificate, the condition entered alone on the lowest used line of Part I should be selected only if it could give rise to all the conditions entered above it Must use the WHO format certificate

Medical Certificate of cause of death Duration I(a) Disease or condition directly leading to death† ................................................................... (b) Other disease or condition, if any, leading to I(a) ......................................................................... (c) Other disease or condition, if any leading to I(b).......................................................................… (d) Other disease or condition, if any leading to I(b).......................................................................… II Other significant conditions CONTRIBUTING TO THE DEATH but not related to the disease or condition causing it ................................................................................

Medical Certificate of cause of death Duration I(a) Disease or condition directly leading to death† .................…………..Carcinomatosis 3 months (b) Other disease or condition, if any, leading to I(a) ....................................Carcinoma of left main bronchus 8 months (c) Other disease or condition, if any leading to I(b).........................................… (d) Other disease or condition, if any leading to I(b).......................................................................… II Other significant conditions CONTRIBUTING TO THE DEATH but not related to the disease or condition causing it ......….......................................................................

Cause of death certificate direct cause Ia renal failure due to b obstructive nephropathy due to c carcinoma of prostate due to d other contributing cause II hypertension ……………………………………………... Underlying cause of death - ICD-10 C61 malignant neoplasm of prostate

If the general principle does not apply 3 Selection rules 5 Modification Rules Volume II of ICD-10 Incorporated into ACME decision tables Rely on use of the WHO format certificate

If the General Principle does not apply ICD Selection rule 1 ...And there is a sequence terminating in the first mentioned condition, select the originating cause of this sequence…. ...if there is more than 1 sequence, select first mentioned

Rule 1 direct cause Ia acute myocardial infarction due to b coronary atherosclerosis due to c parkinson’s disease due to d other contributing cause ……………………………………………... Underlying cause of death - ICD-10 coronary athersclerosis (but modification rule also applies)

If the General Principle does not apply Selection rule 2 .... And there is no reported sequence…. Select the first mentioned condition

Rule 2 direct cause Ia Type I diabetes due to b hypertension and heart failure due to c pneumonia due to d other contributing cause ……………………………………………... Underlying cause of death - E10.9 insulin dependent diabetes without mention of complication

Rule 3 If the condition selected by the General Principle or by Rule 1 or Rule 2 is obviously a direct consequence of another reported condition, whether in Part I or Part II, select this primary condition.”

Rule 3 - cause of death certificate I a volaemic shock b heamatemesis c oesophageal varices d portal hypertension II alcoholic liver cirrhosis UCD is alcoholic liver cirrhosis [in ICD-9 & 10 by rule 3]

Cause of death I a bronchopneumonia b c d II Alzheimer’s disease UCD bronchopneumonia ICD-9 ACCS Alzheimer’s disease ICD-10

Querying cause of death • ICD suggests asking the certifier before applying selection rules • was the renal failure in part I due to the diabetes in part II? • Ask for results of pre or post-mortem tests • bacteriology, histology, toxicology

Querying cause of death • Can the coding office ask the certifier for more information? • Confidentiality • identity of certifier, contact details • Or check the medical records? • How long after the death is the cause coded? • Which deaths do you query? • Why? • Can you amend the cause codes for statistics?

Selecting the underlying cause of death • ICD rules • consistent selection and coding • Must have cause certified in standard WHO format

Automating cause of death coding Incorporates ICD-10: • index assignments • translate English text of each cause to ICD code • selection rules • selects underlying cause • needs information on position of cause on WHO certificate • as agreed by the WHO Mortality Reference Group • incorporates tables of code relationships

Data entry for automated coding • electronic text from certificate • what language? • Translate certificates or software? • Develop native language coding module? • STYX, Mikardo, SuperMICAR • optical character recognition, voice recognition • Enter ICD codes for each condition on certificate • manual multiple cause coding • allow software to select underlying cause

Does automated cause coding make data comparable ? • Application of ICD rules - yes • depends on WHO format certificate • ICD-10 Updates & version control • Coding individual conditions on certificate - maybe • depends on language to code interface • Certification - no • depends on training, medical concepts, quality, legal constraints • Does not remove need for other quality assurance

Prerequisites for mortality statistics through automated cause coding using ACME and related systems • Vital registration • Cause of death certified on WHO format • Quality and completeness of certification acceptable • Either • means of translating text causes in accepted languages into ICD codes • Or • manual cause coders trained to input multiple cause ICD codes

Any questions?

Additional issues if time is available • Modification rules • External causes of death • effects of changes in selection rules on mortality statistics

Coding mortality data