Analysing cause of death trends: Impact of ICD10 implementation

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Analysing cause of death trends Impact of ICD-10
implementation

• Patricia Tully and Patricia Wood
• Statistics Canada

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Outline

• Description of the Canadian Vital Statistics
  System
• Underlying cause of death
• Features of ICD-10
• Impact of ICD-10 implementation on cause of death
  statistics

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Canadian Vital Statistics System

• Provincial/territorial registration of death
• Federal/provincial/territorial agreement
• Data and registration document images to
  Statistics Canada
• Compilation of national database

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Underlying Cause of Death

• Defined by the World Health Organization (WHO) in
  the Tenth Revision of the International
  Classification of Diseases (ICD-10) and earlier
  revisions as
• (a) the disease or injury which initiated the
  train of events leading directly to death, or (b)
  the circumstances of the accident or violence
  which produced the fatal injury.

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History of mortality classification in Canada
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Medical Certificate of Cause of Death
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How is Underlying Cause of Death determined in
ICD-10?

• The General Principle
• When more than one condition is entered on the
  certificate, select the condition entered alone
  on the lowest used line of Part 1 only if it
  could have given rise to all the conditions
  entered above it. (ICD-10, Volume 2)
• Selection Rules 1 to 3
• Modification Rules A to F

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Medical Certificate of Cause of Death
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Major category and code changes from ICD-9 to
ICD-10 Mortality

• Alphanumeric code structure (A00-Y89)
• Number and order of chapters
• Chapters I to XVIII (A00-R99) Diseases
• Chapter XIX (S00-T98) Injury, poisoning and
  certain other consequences of external causes
• Chapter XX (V01-Y89) External causes of morbidity
  and mortality

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Major category and code changes from ICD-9 to
ICD-10 Mortality (continued)

• Number of codes valid for underlying cause of
  death 8,000 in ICD-10 versus 5,000 in ICD-9
• ICD-9
• One code (438) for Late effects of
  cerebrovascular disease
• ICD-10
• Six codes (I69.0-I69.4, I69.8) for Sequelae of
  cerebrovascular disease

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Evaluation of ICD-10 impact on Mortality
Statistics

• New categories new rules disrupted trends in
  causes of death
• How can the size of the impact be measured?
• Conduct a study to code 1999 deaths with both
  ICD-9 and ICD-10 (bridge-coding study)
• Calculate comparability ratios for selected
  detailed causes of death

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How are comparability ratios calculated?

• For a selected cause of death,

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How are comparability ratios used?

• Comparability ratios can be used as factors for
  adjusting cause-of-death-specific mortality
  statistics. For example
• A comparability ratio of 0.70 for a specific
  cause or group of causes means that for every 100
  deaths classified to that cause in ICD-9, there
  would be 70 deaths classified by ICD-10 to the
  comparable cause(s)

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Is there a conversion table?

• A conversion table lists a code from ICD-9 along
  with all the codes in ICD-10 that qualitatively
  correspond to one another
• A conversion table is not a substitute for a
  bridge-coding study
• Bridge-coding yields comparability ratios that
  measure the impact of changes to both codes and
  selection rules

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Areas of greatest expected impact

• Significant discontinuities are expected in cause
  of death trends from 1999 (the last year of
  ICD-9) to 2000 (the first year of ICD-10).

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Areas of greatest expected impact (continued)

• Large decreases are expected in
• Pneumonia and influenza
• Accidental falls
• Vital hepatitis
• Tuberculosis

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Large decreases due to ICD-10 implementation
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Pneumonia and influenza
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Areas of greatest expected impact (continued)

• Large increases are expected in
• Alzheimers disease
• Septicaemia
• Non-malignant neoplasms
• Other and unspecified non-transport accidents and
  their sequelae

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Large increases due to ICD-10 implementation
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Alzheimers disease
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Who to contact at Statistics Canada