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U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Centers for Disease Control and Prevention National Center for Health Statistics. ICD-9 to ICD-10 Comparability: Applicability to Injury Data. Lois A. Fingerhut, MA and Margaret Warner, PhD
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U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Centers for Disease Control and Prevention National Center for Health Statistics ICD-9 to ICD-10 Comparability: Applicability to Injury Data Lois A. Fingerhut, MA and Margaret Warner, PhD Special Projects Branch, Office of Analysis and Epidemiology
Overview • Process of developing ICD-10 codes for external cause matrix • Comparability ratio • Percent agreement • Application of comparability ratio • Comparability for multiple cause diagnosis data
Development of Comparability based on External Cause (EC) of Injury Matrix • Development of ICD-10 EC matrix • Compare ICD-9 to ICD-10 code by code for underlying cause of death • Some movement of codes in ICD-9 matrix based on changes to ICD-10 (e.g. MVT) and updates (e.g. drowning) • Validate with comparability ratios • For trends, ICD-9 EC matrix adjusted to match ICD-10 EC matrix
Final Comparability Ratios by Intent • All injury 1.0159 • Unintentional 1.0251 • Suicide 1.0022 • Homicide 1.0020 • Undetermined 0.9867 • Legal interv/war 0.9235
Effect of Final Comparability Ratios by Intent on 1998 death rates CR CDR CMR • All injury 1.0159 * 53.3=54.1 • Unintentional 1.0251 *34.2= 35.1 • Suicide 1.0022 * 11.1=11.1 • Homicide 1.0020 * 6.5= 6.5 • Undetermined 0.9867 * 1.4= 1.3 • Legal interv/war 0.9235 * 0.1= 0.1 CR- comparability ratio, CDR- crude death rate, CMR- comparability modified rate
Effect of Final Comparability Ratios by Mechanism on 1998 death rates CR CDR CMR • MVT .9545 * 15.3=14.6 • Firearm 1.0012 *11.1=11.1 • Poisoning 1.0192 * 6.7=6.8 • Fall 1.0015 * 4.8= 4.8 • Suffocation 1.0974 *4.0= 4.4
Comparability ratios for external causes of injury with the “worst” ratios
Transportation-related injuries • Not 1-to-1 match for many codes • Often no comparable ICD-10 codes • Almost 20% of all ICD-9 MVT deaths • Comparability ratios • All transport 0 .9930 • Other land transport 2.6350 • Pedal cyclist, MVT 0.8038 • Pedal cyclist, other 1.7477
Other summary measures • Comparability ratio summarizes net effect • Percent agreement between ICD-9 and ICD-10 • Inflows – in ICD-10 but not ICD-9 • Outflows – in ICD-9 but not ICD-10 • Coded to both
Example: Suffocation • Total ICD-9 = 9,888 • Total ICD-10 = 10,851 • CR = 1.0974 (10 % more in 10 than in 9) • Agreement 9,716 88 % • Outflows (ICD-9 & not ICD-10) 172 2 % • Inflows (ICD-10 & not ICD-9)1,135 10 %
Example: Suffocation • Inflows to suffocation (n=1,135) • From Natural Causes 780 69% Pneumonia 208 18% Residual disease 189 17% Pneumonitis 124 11% • From External Causes 355 31%
Multiple cause of death comparability issues for injury diagnoses • No precedent exists, no standard cause of death lists for injury diagnoses • Entity vs Record axis codes • All mentions vs any mention of an injury • ICD-9 and ICD-10 have opposite axes for injury diagnoses • ICD-9 by nature of injury (fractures, open wounds..) • ICD-10 by body region of injury
Multiple cause of death comparability issues for injury diagnoses • Need a standard format to compare ICD-9 and ICD-10 diagnosis or nature of injury codes • A revised Barell Matrix is needed • Current version uses ICD-9 CM injury diagnosis codes • ICD-9 CM codes have 4th and 5th digits • Most mortality codes have only 3 digits • Comparability issues are abundant…
Amputations…. • ICD-9 codes applied only to upper and lower limbs • ICD-10 codes are far more extensive also covering thorax, head, neck, trunk, multiple body regions CR % agreement All Amputations 2.26 27% Matching ‘limb’ codes 0.85 58%
Conclusions • Important to consider comparability • Large differences in transportation codes • Trends: Basic recommendations • If at all possible, do not combine across revisions • Apply CR to 1998 data only • On web in near future-- Death and death rates for ICD-9 comparability modified EC matrix by age and sex • How to deal with nature of injury codes—work in progress
Questions/Comments Lois FingerhutLFingerhut@cdc.govorMargaret WarnerMWarner@cdc.gov