The development, evolution and modifications

of ICD-10: challenges to the international

comparability of morbidity data

Nathalie Jetté MD, MSc, FRCPC

Assistant Professor Neurology and Community Health Sciences

University of Calgary

Co-Investigators: H. Quan, B. Hemmelgarn, C. Maas, S. Drosler, L. Moskal,

W. Paoin, V. Sundararajan, S. Gao, D. Pickett, R. Jakob, B. Üstün and W.A.

Ghali for the IMECCHI Investigators

November 11, 2009

Outline

Background: History of the International Classification

of Diseases (ICD)

General characteristics of ICD-10

Applications of ICD-10 data

Objectives and Results: ICD-10 international modifications and

variations

Discussion: Challenges posed by having international

ICD modifications

History of Classification of Diseases

First attempts at

classifying diseases:

Francois Bossier de

Lacroix (1706-1777)

published “Nosologia

Methodica”

Linnaeus (1707-1778)

and William Cullen

(1710-1790)

History of Classification of Diseases

1893

1st International List of Causes of Death (ILCD) = adopted

1948

World Health Organization (WHO) takes over leadership role

6th revision expanded to code for mortality and morbidity.

International Classification Year

ILCD 1893

ILCD Revision 1 1900

ILCD Revision 2 1909

ILCD Revision 3 1919

ILCD Revision 4 1929

ILCD Revision 5 1938

ICD Revision 6 1948

ICD Revision 7 1955

ICD Revision 8 1965

ICD Revision 9 1975

ICD Revision 10 1989

ICD Revision 11 (in preparation) 2015

History of Classification of Diseases

ICD-9 (1975)

ICD-9 provided additional detail at the level of the four-digit subcategories and some optional five-digit subdivisions.

Example:

345 Epilepsy

345.4 Partial epilepsy with impairment of consciousness

ICD-10 (1989)

International Classification Year

ILCD 1893

ILCD Revision 1 1900

ILCD Revision 2 1909

ILCD Revision 3 1919

ILCD Revision 4 1929

ILCD Revision 5 1938

ICD Revision 6 1948

ICD Revision 7 1955

ICD Revision 8 1965

ICD Revision 9 1975

ICD Revision 10 1989

ICD Revision 11 (in preparation) 2015

General Characteristics of ICD-10

e.g. 345 epilepsy e.g. G40 epilepsy

ICD-10 Applications and its International

Modifications

Original use of ICD was for mortality reporting

Now widely used for morbidity reporting

To serve this need, many countries have developed their own clinical modifications

allow content to be added which has not yet been included in the WHO reference classification

Used extensively for research internationally

ICD-10 International Modifications

Objectives

1. Describe the differences across existing country-

specific ICD-10 modifications

2. Discuss the important challenges that existing

differences pose to the international comparability of

morbidity and mortality data

3. Discuss potential strategic approaches to achieving

better international comparability of future ICD

revisions

Results

Variations in International Coding

A41 = other septicaemia; A41.5 = septicaemia due to other gram-negative organisms

S06 = intracranial injury; S06.2 = diffuse brain injury

Variations in Defining the Main

Condition or the Principal Diagnosis

An important difference between the various ICD-10 clinical

modifications, is how the “main condition” or “principal diagnosis” is

defined.

WHO’s ICD-10:

Defines the main condition as:

“the condition diagnosed at the end of the episode of health care,

primarily responsible for the patient’s need for treatment or

investigation. If there is more than one such condition, the one held

responsible for the greatest use of resources should be selected”.

Variations in Defining the Main

Condition or the Principal Diagnosis

Canada: same as WHO

Australia, Germany, USA:

“the condition established after study to be chiefly responsible for occasioning the patient’s episode of care in hospital”.

Thailand:

“the condition diagnosed at the end of the episode of health care primarily responsible for the patient’s need for treatment or investigation. The main condition must happen before this episode of health care. If there is more than one such condition, the one held responsible for the greatest use of resources should be selected.”

Challenges Posed by Having Different

ICD-10 Clinical Modifications

Variations in defining the main condition or primary diagnosis

Subdigit level comparisons more challenging

WHO publishes six official language versions of ICD-10

Arabic, Chinese, English, French, Russian, Spanish

…but there are 42 language versions of the ICD consistency between the various translations?

Many countries are still only using ICD-9 (e.g. USA will begin using ICD-10-CM in October 2013)

The Road to ICD-11: a Unified

International Clinical Modification

2002 – meeting of WHO Collaborating Centres

Need to monitor all of the ICD-10 modifications

Metadatabase (ICD-10-XM) Includes various country specific ICD-10 versions

Should encourage correspondence and ideally convergence among modifications

Will assist the WHO in updating and revision the ICD ICD-11

Benefits of ICD-10-XM ICD-11

1. More efficient use of people and other resources in the various countries and as a result decrease omissions and errors

2. Play a role as a platform for ICD updates and revisions

3. Would allow for the comparability of morbidity data internationally

4. No need for conversion mapping softwares which can be costly

Conclusion and Future Directions

The threat to the comparability of international clinical morbidity data is real due to so many country specific versions of ICD-10.

WHO Member States must collaborate with the WHO to ensure all country specific modifications are entered into the WHO meta-database.

Adapting a universal classification would remove the threat to the comparability of international ICD data and should result in:

More efficient resource use

Less errors and omissions

Overall improved reporting of international epidemiologic morbidity data

Co-Investigators

Canada Song Gao

Bill Ghali

Brenda Hemmelgarn

Lori Moskal

Hude Quan

Germany Saskia Drosler

Christina Maas

Australia Vijaya Sundararajan

Thailand Wansa Paoin

USA Donna Pickett

WHO Robert Jakob

Bedihran Ustun

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http://www.who.int/classifications/icd/en/HistoryOfICD.pdf.

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