From ICD-9 to ICD-10: Evaluating the Impact for Healthy People 2010 Manon Boudreault, M.P.H. National Center for Health Statistics

International Classification of Diseases (ICD) History Since 1900, ICD revised about every 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

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 Study: Measure Effect of Revision

Comparability Ratio D i,ICD-10 D i,ICD-9 Measures discontinuity related solely to a revised ICD i C i =

HP2010 Selected Estimated CRs * Obj. No. Cause Same Deaths coded to ICD-10 Same Deaths coded to ICD-9 CR= (ICD-10 divided by ICD-9) 95% CI HIV 12,765 11, (1.14, 1.15) 16-1f Birth Defects 5,950 7, (.8362,.8577) 24-1 Asthma (all ages) 4,217 4, (.8819,.9057) 26-3 Drug- induced 1, (1.15, 1.24) *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) D i,ICD-9 = D i,ICD-9 C i CM

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 ) Fatality Analysis Reporting System (obj b, 15-16, 26-1) National Surveillance System for Pneumoconiosis (obj )

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 Changes Impact 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 /49-12.htm Mortality Database… Session 38 …Wednesday…Ambassador Ballroom Natality Data Files… Session 42 …Wednesday…Congressional Room