The Tenth Revision of the International Classification of Diseases (ICD-10) is already being used to classify mortality data in the U.S. (beginning with 1999 mortality data). The introduction of a new revision of the ICD can create major discontinuities in trend data. The purpose of this paper is to explain and quantify the discontinuity between ICD-9 and ICD-10. The extent of the discontinuity is measured using a "comparability ratio," which results from double-coding a large sample of the national mortality file, once by the old revision (ICD-9), and again by the new revision (ICD-10), and expressing the results of the comparison as a ratio of deaths for a cause of death by ICD-10 divided by the number of that cause of death coded and classified by ICD-9. Using a very large sample of double-coded 1996 mortality records, preliminary comparability ratios are presented for 113 selected causes of death. Major causes of death with ratios that indicate a substantial change between revisions are discussed both in terms of the reasons for the changes and the implications for understanding the mortality trends for these causes from 1998 (the last year of the Ninth Revision) and 1999 (the first year of the Tenth Revision).
Learning Objectives: Participant will understand the statistical consequences of introducing new revisions of the International Classification of Diseases, and how these consequences are measured as comparability ratios
Keywords: Death, Mortality
Presenting author's disclosure statement:
Organization/institution whose products or services will be discussed: None
I do not have any significant financial interest/arrangement or affiliation with any organization/institution whose products or services are being discussed in this session.