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Cleo Rooney

Office for National Statistics

London, England

Coding mortality data

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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

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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

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Comparability of data depends on

• Data collection• data processing

– including coding • analysis• interpretation

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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

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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

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Prerequisites

• Vital Registration system• ‘Medical’ certification of cause of death• cause of death coders trained in

– manual ICD codingor

– automated ICD coding

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Vital registration

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

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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

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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?

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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?

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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

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• 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.

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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

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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 ................................................................................

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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 ......….......................................................................

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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

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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

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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

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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)

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If the General Principle does not apply

Selection rule 2

.... And there is no reported sequence…. Select the first mentioned condition

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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

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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.”

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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]

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Cause of death

I a bronchopneumonia

b

c

d

II Alzheimer’s disease

UCD

bronchopneumonia ICD-9 ACCS

Alzheimer’s disease ICD-10

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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

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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?

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Selecting the underlying cause of death

• ICD rules • consistent selection and coding

• Must have cause certified in standard WHO format

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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

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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

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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

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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

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Any questions?

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Additional issues if time is available

• Modification rules• External causes of death• effects of changes in selection rules on mortality

statistics

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