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Learn about the history of the International Classification of Diseases (ICD) and the major differences between ICD-9 and ICD-10. Evaluate the impact of the transition on Healthy People 2010 data and mortality objectives.
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From ICD-9 to ICD-10: Evaluating the Impact for Healthy People 2010Manon Boudreault, M.P.H. National Center for Health Statistics
International Classification of Diseases (ICD) History • Since 1900, ICD revised about every 10-20 years • All revisions have had an impact on comparability • Variations in statistics due to differing coding rules used rather than a change in disease entity
History…. • Beginning with deaths occurring in 1999, ICD-10 implemented • Many systematic differences between ICD-9 and ICD-10 • Between 1979 and 1998, ICD-9 in use
Major Differences in ICD-10: • Rules for coding and selecting underlying cause of death have changed • Greater detail about the type or site of the disease (from about 5,000 to 8,000 categories ) • An increased number of perinatal codes
Major differences between ICD-9 and ICD-10 … • Chapters have been added and rearranged • Cause-of-death titles have been changed and regrouped • Alphanumeric codes
Cause-Specific HP2010 Mortality Objectives • About 40 objectives, most use the National Vital Statistics System as data source
Baseline History • Baseline data were initially classified and coded to: World Health Organization’s Ninth Revision of the International Classification of Diseases (ICD-9) • Used by virtually all countries to code and classify causes of death
Comparability Study: Measure Effect of Revision • Same death certificates coded to each ICD version • Comparability Ratio (derived from dual classification): • ICD-10 coded deaths • divided by • ICD-9 coded deaths • May be able to adjust older data (total) with comparability ratio
Comparability Ratio Ci = Di,ICD-10 Di,ICD-9 Measures discontinuity related solely to a revised ICD
HP2010 Selected Estimated CRs* *Source: National Vital Statistics System-Mortality, NCHS (Preliminary data), Comparability Ratio (CR) calculated using large sample of 1996 deaths, except for HIV deaths (1998 deaths)
Comparability Ratio (CR) … • Currently available for objectives where data source is the National Vital Statistics System-Mortality • Where HP2010 ICD-9 codes are different, CRs have been calculated in a separate HP2010 report • Is not appropriate to apply to data for objectives that use “multiple-cause-of-death” (e.g., diabetes)
Comparability-Modified Deaths (or Rate) CM Di,ICD-9= Di,ICD-9Ci
Comparability Ratio CAUTION!!!! • CR of 1 does not necessarily mean cause of death was totally unaffected by revision • Unknown if appropriate to use on age-, race-, sex-, or State-specific mortality data • In theory CRs could be applied to subgroups, in practice there are differences in cause-of-death distribution
HP 2010 Steering Committee Response • Unanimous vote to change baseline years for cause-specific mortality objectives to 1999 • Data years will be based on the same classification system (ICD-10) • 1997 or 1998 (primarily) baselines replaced
Effect on 2010 Targets • Baseline revisions were minor • No targets were changed at the time baselines were changed
Other HP2010 Mortality Sources • U.S. Renal Data System (obj. 4-2) • Census of Fatal Occupational Injuries (obj. 20-01) • Fatality Analysis Reporting System (obj. 15-15b, 15-16, 26-1) • National Surveillance System for Pneumoconiosis (obj. 20-04)
Other HP2010 Mortality Data Sources • Baseline evaluations, in process now • Case-by-case basis, • may not use ICD coding solely in their identification
From ICD-9 to ICD-10: Impact on HP2010 data • Most HP2010 cause-specific mortality objectives baselines changed • Some groupings of death codes changed (noted in Tracking HP2010, operational definitions) • Food allergy deaths –anaphylaxis (obj. 10-4) now measurable with ICD-10, specific codes
Other Vital Statistics ChangesImpact on HP2010 data • Upcoming certificate changes: • More complete race data expected • Some objectives will become measurable: Gestational diabetes (Objective 5-08) Recommended weight gain during pregnancy (Objective 16-12)
For More Information On.. • Comparability ICD-9/10… Session 24..next Concurrent Session …Diplomat Room • Comparability report http://www.cdc.gov/nchs/products/pubs/pubd/nvsr/49/49-12.htm • Mortality Database… Session 38 …Wednesday…Ambassador Ballroom • Natality Data Files… Session 42 …Wednesday…Congressional Room