Lois A. Fingerhut, MA and Margaret Warner, PhD Special Projects Branch, Office of Analysis and Epidemiology 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

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 Unintentional Suicide Homicide Undetermined Legal interv/war

Effect of Final Comparability Ratios by Intent on 1998 death rates CR CDR CMR All injury * 53.3=54.1 Unintentional *34.2= 35.1 Suicide * 11.1=11.1 Homicide * 6.5= 6.5 Undetermined * 1.4= 1.3 Legal interv/war * 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 *11.1=11.1 Poisoning * 6.7=6.8 Fall * 4.8= 4.8 Suffocation *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 Other land transport Pedal cyclist, MVT Pedal cyclist, other1.7477

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 = (10 % more in 10 than in 9) Agreement 9,71688 % Outflows (ICD-9 & not ICD-10) % Inflows (ICD-10 & not ICD-9) 1, %

Example: Suffocation Inflows to suffocation (n=1,135) From Natural Causes780 69% Pneumonia20818% Residual disease18917% Pneumonitis12411% From External Causes355 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 4 th and 5 th 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 % Matching ‘limb’ codes %

Nature of injuryComparability ratio Percent agreement All ‘nature of injury’ (w/o comp. care) Fractures Poisoning Upper and lower extremities ??? Much more detail in ICD-10! ??

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 Fingerhut or Margaret Warner