ILLINOIS DEPARTMENT OF PUBLIC HEALTH

In 1999, the new revision to the International Classification of Diseases -- the ICD-10 -- became the new standard for reporting cause of death. From 1978 through 1998, the ICD-9 was the standard classification system used to report mortality statistics.

There are considerable changes in classification and grouping of disease codes between ICD-9 and ICD-10. Though these changes do not affect the comparison of overall number of deaths reported before and after 1999, it may affect the statistics for specific cause-of-death groups. This makes direct comparison of cause-specific mortality problematic across the two periods.

The Illinois resident mortality statistics reported through this query system are presented separately for the years 1994 to 1998, and for 1999 and later. Each period contains its own data dictionary:

• Mortality Database Data Dictionary for 1994 - 1998 (cause of death based on ICD-9 codes)
  
  
• Mortality Database Data Dictionary for 1999 - 2014 (cause of death based on ICD-10 codes)