The development, evolution, and modifications of ICD-10: challenges to the international comparability of morbidity data.
BACKGROUND
The United States is about to make a major nationwide transition from ICD-9-CM coding of hospital discharges to ICD-10-CM, a country-specific modification of the World Health Organization's ICD-10. As this transition occurs, the WHO is already in the midst of developing ICD-11. Given this context, we undertook this review to discuss: (1) the history of the International Classification of Diseases (a core information "building block" for health systems everywhere) from its introduction to the current era of ICD-11 development; (2) differences across country-specific ICD-10 clinical modifications and the challenges that these differences pose to the international comparability of morbidity data; (3) potential strategic approaches to achieving better international ICD-11 comparability.


BACKGROUND
A literature review and stakeholder consultation was carried out. The various ICD-10 clinical modifications (ICD-10-AM [Australia], ICD-10-CA [Canada], ICD-10-GM [Germany], ICD-10-TM [Thailand], ICD-10-CM [United States]) were compared. These ICD-10 modifications differ in their number of codes, chapters, and subcategories. Specific conditions are present in some but not all of the modifications. ICD-11, with a similar structure to ICD-10, will function in an electronic health records environment and also provide disease descriptive characteristics (eg, causal properties, functional impact, and treatment).


CONCLUSIONS
The threat to the comparability of international clinical morbidity is growing with the development of many country-specific ICD-10 versions. One solution to this threat is to develop a meta-database including all country-specific modifications to ensure more efficient use of people and resources, decrease omissions and errors but most importantly provide a platform for future ICD updates.
Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada. nathalie.jette@albertahealthservices.ca
Nathalie
N
Jetté
Hude
H
Quan
Brenda
B
Hemmelgarn
Saskia
S
Drosler
Christina
C
Maass
Lori
L
Moskal
Wansa
W
Paoin
Vijaya
V
Sundararajan
Song
S
Gao
Robert
R
Jakob
Bedihran
B
Ustün
William A
WA
Ghali
D001315:Australia; D002170:Canada; D059019:Clinical Coding / Q000592:standards*; D004059:Diffusion of Innovation; D004194:Disease / Q000145:classification*; D005858:Germany; D006801:Humans; D038801:International Classification of Diseases / Q000592:standards*; D007391:International Cooperation; D008499:Medical Records / Q000145:classification*; D019984:Quality Indicators, Health Care / Q000592:standards*; D011787:Quality of Health Care / Q000592:standards; D017751:Safety Management; D013785:Thailand; D014481:United States