International variation in the definition of 'main condition' in ICD-coded health data

Int J Qual Health Care. 2014 Oct;26(5):511-5. doi: 10.1093/intqhc/mzu064. Epub 2014 Jul 2.


Hospital-based medical records are abstracted to create International Classification of Disease (ICD) coded discharge health data in many countries. The 'main condition' is not defined in a consistent manner internationally. Some countries employ a 'reason for admission' rule as the basis for the main condition, while other countries employ a 'resource use' rule. A few countries have recently transitioned from one of these approaches to the other. The definition of 'main condition' in such ICD data matters when it is used to define a disease cohort to assign diagnosis-related groups and to perform risk adjustment. We propose a method of harmonizing the international definition to enable researchers and international organizations using ICD-coded health data to aggregate or compare hospital care and outcomes across countries in a consistent manner. Inter-observer reliability of alternative harmonization approaches should be evaluated before finalizing the definition and adopting it worldwide.

Keywords: benchmarking; international classification of disease; measurement of quality; standards.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Clinical Coding / standards*
  • Hospital Administration / standards*
  • Humans
  • International Classification of Diseases / standards*
  • Internationality*
  • Reproducibility of Results